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Protective effect of Pseudomonas fluorescens as a

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Problem : Vibriosis in aquaculture

Definition and introduction of Vibriosis
Vibriosis is one of the most prevalent fish diseases caused by bacteria belonging to the genus Vibrio. Vibriosis caused by Vibrio anguillarum,a polarly flagellated, gram-negative, curved rod, has been particularly devastating in the marine culture of Salmonid and Perciformes fish.

Vibriosis occurs in cultured and wild marine fish in salt or brackish water, particularly in shallow waters during late summer. It was originally believed that scavenger fish feeding around the farms were the natural reservoir of V. anguillarum, and contact between fish seems to be an important factor for the spread of this pathogen. However, there is evidence that V. anguillarum is normally present in the intestinal microflora and food of cultured and wild healthy fish. The temperature and quality of the water, the virulence of the V. anguillarum strain and stress on the fish are important elements influencing the onset of disease outbreaks.

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Ways to control outbreak of vibriosis : By using probiotic bacteria
The possibilities for using probiotics as a prophylactic approach have gained much interest in the last years (Skjermo and Vadstein, 1999). Important probiotic strains can be isolated from indigenous and exogenous microbiota of aquatic experiments in penaeid aquaculture ponds have shown that the addition of the selected strains of Bacillus like Bacillus subtilis to pond water reduces Vibrio harveyi-caused mortality.

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Vibriosis in aquaculture | Novriadi | Omni-Akuatika

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Inhibitory effects of Bacillus probionts on growth and toxin production of Vibrio harveyi pathogens of shrimp

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Aim:  To investigate the effects of Bacillus subtilis, Bacillus licheniformis and Bacillus megaterium in terms of toxin and growth of pathogenic Vibrio harveyi.Methods and Results:  Three Bacillus probionts...

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bacterial diseases of shrimps and their management

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Bacterial diseases of shrimps and their management - ppt video online download

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Vibriosis and related bacterial diseases Vibrio spp. - form major cultivable bacteria isolated from diseased penaeid shrimp opportunistic pathogens some behave like true pathogens Main species : V. alginolyticus, V. parahaemolyticus V. harveyi, V. splendidus, V. vulnificus and V. damsela. Other gram-negative rods Flavobacterium spp. Pseudomonas spp and Aeromonas spp

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addition information about vibriosis in shrim

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addition information about vibriosis in shrim

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Isolation of Vibrio harveyi bacteriophage with a potential for biocontrol of luminous vibriosis in hatchery environments - ScienceDirect

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A double stranded DNA bacteriophage of Vibrio harveyi was isolated from shrimp farm water from the west coast of India. The isolated phage belonged to the family Siphoviridae. Its broad lytic activity against V. harveyi isolates both from the west and east coast of India suggested that it had a potential for biocontrol of luminous vibriosis due to V.

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Vibrio is a genus of Gram-negative bacteria, possessing a curved-rod shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Typically found in salt water, Vibrio species are facultative anaerobes that test positive for oxidase and do not form spores.

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Flesh-eating bacteria: what you need to know to about vibriosis to avoid infection - TomoNews

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HOUSTON - On June 28, 50-year-old Texas man Brian Parrott had to have his leg amputated after he contracted a flesh-eating bacterial infection from swimming in the Gulf of Mexico. The flesh-eating, hook-shaped bacteria is called vibrio, of which there are about a dozen species.

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Info about Bacillus subtilis BT23, a possible probiotic treatment for black tiger shrimp, Penaeus monodon

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Info about Bacillus subtilis BT23, a possible probiotic treatment for black tiger shrimp, Penaeus monodon

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This presentation tells us about the Bacillus Subtilis -- Created with PowToon -- Thanks for 2,000 views, can we hit 5,000?

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Bacillus species principally B. subtilis are one of the most investigated bacteria for animal probiotic development due to:
a) versatility of growth nutrients utilization,
b) high level of enzymes production,
c) secretion of antimicrobial compounds,
d) spore producers,
e) develops in aerobic and anaerobic conditions
f) B. subtilis is Generally Recognized As Safe (GRAS) by the Food and Drug Administration (FDA).

Functional feeds development with alternative-economic nutrient vegetable sources of proteins, carbohydrates, lipids and Bacillus subtilis probiotic strains, must be considered in shrimp/fish aquaculture production systems; as an option to eliminate animal feed ingredients, improves digestion-assimilation, reduce water pollution and diseases, and to increase yields and profits.

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Epizootic ulcerative syndrome (EUS), also known as mycotic granulomatosis (MG) or red spot disease (RSD), is a disease caused by the water mould Aphanomyces invadans. It infects many freshwater and brackish fish species in the Asia-Pacific region and Australia. The disease is most commonly seen when there are low temperature and heavy rainfall in tropical and sub-tropical waters. Aphanomyces is a member of a group of organisms formerly commonly known as water moulds; means that they are in fungi group. To solve this , we have to put some fungivores into the breeding site . Fungivores are defined as any organism that feed on fungi as their needs . When we put this two organism together , the fungivores will engulf and kill the Aphanomyces A and thus lowering the risk of fish to get red spot . Example of fungivores are trichoderma The fungal genus, Trichoderma produces enzymes such as chitinases which degrade the cell walls of other fungi.[14] They are able to detect other fungi and grow towards them, they then bind to the hyphae of other fungi using lectins on the host fungi as a receptor, forming an appressorium. Once this is formed, Trichoderma inject toxic enzymes into the host and probably peptaibol antibiotics, which create holes in the cell wall, allowing Trichoderma to grow inside of the host and feed. By using trichoderma , we can easily kill the Aphanomyces A and produce healthier fish crops . This is just a suggestion. It not yet fully discovered.

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Epizootic ulcerative syndrome (EUS), also known as mycotic granulomatosis (MG) or red spot disease (RSD), is a disease caused by the water mould Aphanomyces invadans. It infects many freshwater and brackish fish species in the Asia-Pacific region and Australia. The disease is most commonly seen when there are low temperature and heavy rainfall in tropical and sub-tropical waters. Aphanomyces is a member of a group of organisms formerly commonly known as water moulds; means that they are in fungi group. To solve this , we have to put some fungivores into the breeding site . Fungivores are defined as any organism that feed on fungi as their needs . When we put this two organism together , the fungivores will engulf and kill the Aphanomyces A and thus lowering the risk of fish to get red spot . Example of fungivores are trichoderma The fungal genus, Trichoderma produces enzymes such as chitinases which degrade the cell walls of other fungi.[14] They are able to detect other fungi and grow towards them, they then bind to the hyphae of other fungi using lectins on the host fungi as a receptor, forming an appressorium. Once this is formed, Trichoderma inject toxic enzymes into the host and probably peptaibol antibiotics, which create holes in the cell wall, allowing Trichoderma to grow inside of the host and feed. By using trichoderma , we can easily kill the Aphanomyces A and produce healthier fish crops . This is just a suggestion. It not yet fully discovered.

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Problem : stress inducible furunculosis infection  Microbe : pseudomonas flurescens                      Function of microbe : exclude a pathogenic from athlantic salmon

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Problem : stress inducible furunculosis infection  Microbe : pseudomonas flurescens                      Function of microbe : exclude a pathogenic from athlantic salmon

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Application of Enterococcus faecium as probiotic in aquatic species 

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Application of Enterococcus faecium as probiotic in aquatic species 

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Due to the rapid growth of aquaculture particularly in fish and shrimp farming industries, there is a constant threat of infectious diseases. According to studies, the species Aeromonas and Vibrio are the most common pathogenic microorganisms that affect these industries. In order to control the attack of this microorganisms, antibiotics have been used. Though, the use of antibiotics had led to resistance and limitations in market production. In the study, it has been proved that probiotic used in aquatic species is helpful in their health and survival.The use of probiotic can stimulate the development of a healthy gut microflora and can inhibit pathogenic bacteria like Vibrio spp., Yersinia spp. and Aeromonas spp.

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Hence, selection criteria of probiotics for aquaculture should be based on their antagonism towards pathogens (through competitive exclusion), their growth, attachment to intestinal mucus and production of beneficial compounds (Vine et al., 2004). Since fish and shrimp are cultured under different conditions the optimum temperature range should also be considered for selection of the right probiotic strain. Another important factor is that probiotics always lack pathogenicity. After all, probiotics should contribute to efficient production in a sustainable way, promoting healthy and robust animals (Brittain et al., 2002).

Lactic acid bacteria (LAB) are potential probiotic candidates in aquaculture and are also known to be present in the intestine of healthy fish. Enterococcus faecium is one of the most commonly used lactic acid producing bacteria in animal nutrition and has become a focus of attention for use in commercially farmed aquatic species. Enterococci are Gram-positive, facultative anaerobic bacteria which are widely distributed in nature and considered as bacteria of low pathogenicity (Klare et al., 2003). Probiotic enterococci infections haven´t been reported in the veterinary medicine, so the risk appears to be limited (Rinkinen et al., 2003). Eaton and Gasson (2001) found that E. faecium strains were also generally free of virulence determinants. Concerning possible acquired antibiotic resistances, testing the antibiotic profile of enterococci used as probiotics is of relevance. However, these antibiotic resistances are species- or genus-specific properties (Klare et al., 2003). Once the probiotic enterococci are accurately identified, they can be tested for specific resistances.

Several important ways in which probiotics producing lactic acid (such as E. faecium) can provide a performance benefit are improving intestinal microbial balance (Fuller, 1989), stimulating the immune system and decreasing pH as well as the release of bacteriocins (Rolfe, 2000). Bacteriocins are small peptides which are characterized by their ability to inhibit pathogenic bacteria; whereas, some have a narrow spectrum of activity while others inhibit a wide variety of bacteria.

The use of the bacteriocin-producing E. faecium with probiotic properties alone or in combination with other beneficial intestinal bacteria was investigated in different studies.

In vitro studies using the agar spot method (Rosskopf, 2010) have shown that Enterococcus faecium (strain IMB 52) has inhibition properties against a wide spectrum of aquatic pathogens including Yersinia ruckeri, Vibrio harveyi, Streptococcus agalactiae and Aeromonas veronii. Similar observation was made by Swain et al. (2009) who proved the inhibitory activity of E. faecium isolated from brackishwater fish against V. harveyi and V. parahaemolyticus. This demonstrates the potential applications of E. faecium from fish intestine for controlling pathogenic vibriosis in shrimp culture. It has also been reported that survival rates of European eels (Anguilla Anguilla L.) fed with E. faecium were significantly higher than in the control groups after challenged with Edwardsiella tarda (Chang and Liu, 2002).

Wang et al. (2008) demonstrated that the addition of E. faecium (1 x 10 ⁷ CFU/mL) in aquaria water could significantly increase final weight and daily weight gain (DWG) of tilapia. Since certain immunological parameters (myeloperoxidase and respiratory burst activity) of tilapia were improved as well, the increased growth performance might be attributed to less bacterial challenge, confirming the benefit for the non-specific innate immunity of this kind of fish.

Panigrahi et al. (2007) examined immune modulation including cytokine gene expressions of rainbow trout (Oncorhynchus mykiss) and demonstrated that these parameters were improved by probiotic feeding of freeze-dried Lactobacillus rhamnosus, Enterococcus faecium or Bacillus subtilis (10 ⁹ CFU/g) after 45 days. Particularly the fish fed the E. faecium strain showed better performance which could possibly be linked to the suitable ambient temperature conditions of this strain. Temperature is a major environmental factor controlling microbial growth and the ideal conditions differ among microorganisms. E. faecium was found to be more psychrotolerant than the other two bacteria, growing well at temperatures ranging from 12 to 30 °C. Rosskopf (2010) showed that the optimum temperature range for E. faecium (strain IMB 52) reaches as far as to 37 °C.

Using the fluorescence in situ hybridization (FISH) technique, Supamattaya et al. (2005, 2006) have demonstrated in a series of in vivo studies that E. faecium (strain IMB 52) is also able to populate the intestine of white shrimp (Litopenaeus vannamei) and Nile tilapia (Oreochromis niloticus) (Picture 3 and Table 1) and induce a positive impact on bacterial ecology of the gut by inhibiting Vibrio spp. through competitive exclusion. E. faecium was even detected in the fish gut and faeces 10 days after product administration. In addition, it was observed that dietary application of E. faecium (strain IMB 52) alone or in combination can improve growth performance, enhance the immune response (by increasing granular hemocytes level) (Supamattaya et al., 2005) and increase survival rate in shrimp contaminated with Vibrio parahaemolyticus (Krummenauer et al., 2009).

E. Faecium in Tilapia's Intestine and Faeces at Day 1 and Day 10 After Stopping to Feed Probiotics Including this Probiotic Strain

Means ± SD. Using Fluorescent in situ hybridization (FISH), 5 - 15 microscopic fields were counted.

From these studies it was concluded that Enterococcus faecium (strain IMB 52) is a safe and promising probiotic candidate for aquatic species which can be applied in different combinations.

Conclusion

Maintaining the balance of critical parameters and effective disease control remain fundamental requirements for successful aquaculture. In order to withstand the high stocking densities in shrimp and fish production probiotics are a promising feed additive to stimulate animal growth and advance disease resistance. Enterococcus faecium as probiotic strain in aquatic species is increasingly recognized as safe and can be applied in different combinations. E. faecium can grow at a wide range of temperatures and thus has an advantage over other bacteria considering that fish and shrimp are reared at different temperatures and conditions.

The current paper illustrated with in vitro studies and performance trials the potential benefits of E. faecium as probiotic feed additive for fish and shrimp, either by stimulating the development of a healthy gut microflora or by inhibiting pathogenic bacteria like Vibrio spp., Yersinia spp. and Aeromonas spp.

References

Brittain A, Lee CS, O´Bryen PJ (2002) Workshop discussion and recommendations on "Microbial contributions to aquatic nutrition". In: Microbial approaches to aquatic nutrition within environmentally sound aquaculture production systems. The World Aquaculture Society, United States.

Chang CI, Liu WY (2002) An evaluation of two probiotic bacterial strains, Enterococcus faecium SF68 and Bacillus toyoi, for reducing edwardsiellosis in cultured European eel, Anguilla Anguilla L. Journal of Fish Diseases 25 (5): 311 - 315.

Eaton TJ, Gasson MJ (2001) Molecular screening of Enterococcus virulence determinants and potential for genetic exchange between food and medical isolates. Appl. Environ. Microbiol. 67: 1628 - 1635.

Fuller R (1989) Probiotics in man and animal. Journal of Applied Bacteriology 66: 365 - 375.

Klare I, Konstabel C, Badstübner D, Werner G, Witte W (2003) Occurrence and spread of antibiotic resistances in Enterococcus faecium. International Journal of Food Microbiology 88: 269 - 290.

Krummenauer D, Abreu PC, Lara G, Poersch L, Encarnacao P, Wasielesky Jr W (2009) The Effect of Probiotic in Litopenaeus vannamei Biofloc Technology Culture System contaminated with Vibrio parahaemolyticus. Abstract World Aquaculture Conference, Mexico.

Panigrahi A, Kiron V, Satoh S, Hirono I, Kobayashi T, Sugita H, Puangkaew J, Aoki T (2007) Immune modulation and expression of cytokine genes in rainbow trout Oncorhynchus mykiss upon probiotic feeding. Developmental and Comparative Immunology 31: 372 - 382.

Rinkinen M, Jalave K, Westermarck E, Salminen S, Ouwehand AC (2003) Interaction between probiotic lactic acid bacteria and canine enteric pathogens: a risk factor for intestinal Enterococcus faecium colonization? Veterinary Microbiology 92: 111 - 119.

Rolfe RD (2000) The Role of Probiotic Cultures in the control of Gastrointestinal Health. Symposium: Probiotic Bacteria: Implications for Human Health. The Journal of Nutrition: 396S - 402S.

Rosskopf S (2010) In vitro Evaluation of Inhibitory Activities of Probiotics against Aqua-pathogens for their possible Use in Aquacultures. Bachelorthesis, Biomin Holding GmbH, Tulln.

Supamattaya K , Viriyapongsutee B, Ruangsri J, Encarnacao P, Schatzmayr G (2005) Effect of probitoic Enterococcus faecium and Phycophytic Substances on Growth Performance and Health Condition of White Shrimp (Penaeus vannamei).

Swain SM, Singh C, Arul V (2009) Inhibitory activity of probiotics Streptococcus phocae PI80 and Enterococcus faecium MC13 against Vibriosis in shrimp Penaeus monodon. World J Microbiol Biotechnol 25: 697 - 703.

Vine NG, Leukes WD, Kaiser H (2004) In vitro growth characteristics of five candidate aquaculture probiotics and two fish pathogens grown in fish intestinal mucus. FEMS Microbiology Letters 231: 145 - 152.

Wang YB, Tian ZQ, Yao JT, Li WF (2008) Effect of probiotics, Enterococcus faecium, on tilapia (Oreochromis niloticus) growth performance and immune response. Aquaculture 277: 203 - 207.

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Application of Enterococcus Faecium as a Probiotic Strain in Aquatic Species

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Hence, selection criteria of probiotics for aquaculture should be based on their antagonism towards pathogens (through competitive exclusion), their growth, attachment to intestinal mucus and production of beneficial compounds (Vine et al., 2004). Since fish and shrimp are cultured under different conditions the optimum temperature range should also be considered for selection of the right probiotic strain.

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Effect of probiotics, Enteroccus faecium, on tilapia (Oreochromis niloticus) growth performance and immune response - ScienceDirect

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The aim of this study was to analyze the effect of a probiotic bacterium, Enterococcus faecium ZJ4 on growth performances and immune responses of tilapia ( Oreochromis niloticus). The tilapias were treated with E. faecium ZJ4 at a final concentration of 1 × 10 7 cfu ml − 1 in aquaria water every 4 days.

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Also known as hay bacillus

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Different applications of probiotics in aquaculture

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Different applications of probiotics in aquaculture

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ABSTRACT: Use of Pseudomonas sp. strain MT5 to prevent and treat Flavobacterium columnare infection was studied in 2 experiments with fingerling rainbow trout Oncorhynchus mykiss. In the first experiment, length heterogeneity analysis of PCR-amplified DNA fragments (LH-PCR) was used to assess the effect of antagonistic baths on the microbial diversity of healthy and experimentally infected fish. In the 148 samples studied, no difference was found between bathed and unbathed fish, and 3 fragment lengths were detected most frequently: 500 (in 75.7% of the samples), 523 (62.2%) and 517 bp (40.5%). The species contributing to these fragment sizes were Pseudomonas sp., Rhodococcus sp. and F. columnare, respectively. A specific PCR for detection of Pseudomonas sp. MT5 was designed, but none of the tissue samples were found to be positive, most likely indicating poor adhesion of the strain during bathing. LH-PCR was found to be a more powerful tool for detecting F. columnare in fish tissue than traditional culture methods (χ² = 3.9, df = 1, p < 0.05). Antagonistic baths had no effect on the outbreak of infection or on fish mortality. F. columnare was also detected in healthy fish prior to and after experimental infection, indicating that these fish were carriers of the disease. In the second experiment, intensive Pseudomonas sp. MT5 antagonistic baths were given daily to rainbow trout suffering from a natural columnaris infection. Again, the antagonistic bacteria had no effect on fish mortality, which reached 95% in both control and antagonist-treated groups in 7 d.

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Antibiotic resistance associated with veterinary drug use in fish farms

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Antibiotic resistance associated with veterinary drug use in fish farms

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Antibiotic resistance in Aeromonas salmonicida

In the 1950s, furunculosis in salmonid hatcheries in the USA was treated with sulphonamides, and an early report on acquired sulphonamide resistance in Aeromonas salmonicida comes from Leetown, West Virginia, with 36 out of 47 isolates from brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) found to be resistant in 1955.³ In this report, the devastating effect of acquired sulphonamide resistance in the treatment of furunculosis was demonstrated by clinical trials. The resistant strain has since been shown to contain transferable resistance to both sulphonamides and tetracyclines.5,34

In France in 1971, 104 isolates of A. salmonicida were reported to be 100% resistant to sulphonamides while only 11.5% of the isolates were resistant to the antibiotics tetracycline, streptomycin and/or chloramphenicol.³⁵ Half of the drug-resistant Japanese A. salmonicida from salmonids in the 1960s had R plasmids hosting the drug resistance genes. Sulphonamides, tetracyclines, chloramphenicol and streptomycin were ineffective, although streptomycin was not used in the control of fish diseases.5

A study of drug resistance in A. salmonicida isolated from the intestinal tract of diseased pond-reared Amago (O. rhodurus macrostomus) and Yamame (O. masou ishikawae) was conducted in the early 1970s.³⁶ Fish ponds from the Nagano, Gifu, Shiga and Tokyo districts of Japan were studied, and all ponds (24) were supplied with fresh flowing water from springs or mountain streams. The drugs used for treating diseased fish in the ponds were chloramphenicol, sulphonamides, and to a minor extent tetracyclines. All the A. salmonicida isolates (20) found on media with chloramphenicol contained transferable R plasmids conferring resistance towards sulphonamides, streptomycin and chloramphenicol. A large portion of the Aeromonas liquefaciens(hydrophila) strains isolated from the pond-reared fish in this study also contained a transferable R plasmid conferring resistance to sulphonamides, streptomycin and chloramphenicol.

The transferable R plasmids with resistance towards sulphonamides, streptomycin and chloramphenicol isolated from both A. salmonicida and A. liquefaciens (hydrophila) were found to be of the same size and same incompatibility group.³⁷No exchange of salmonid fish between different areas had occurred because this was restricted in an attempt to reduce transmittance of various diseases. In spite of that, the same R plasmid was detected in all fish farms in the four different districts in Japan, indicating that the plasmid occurred naturally in the environmental flora of the freshwater systems.

A. salmonicida isolated during 1979–81 from fish farms in eight districts in Japan, including farms from three of the four districts studied by Aoki et al. in 1972,³⁶ were investigated for antibiotic resistance.³⁹ Of 129 isolates, only five were found to be susceptible to all antibiotic drugs tested. The other isolates were found to be resistant to up to six drugs. In particular, resistance was detected against quinolones and nitrofurans. Only two of the 124 resistant isolates studied were found to transfer drug resistance by R plasmids. These two isolates hosted an R plasmid (29 MDa) conferring resistance against sulphonamides, chloramphenicol and streptomycin. Variants of this IncU R plasmid have been found in Aeromonas bacteria all over the world.18,41,50

In 1989 in Atlantic salmon (Salmo salar) farms on the western coast of Norway, it was found that infections caused by atypical Aeromonas salmonicida could not be controlled with the quinolone drug oxolinic acid because of chromosomal quinolone resistance. In addition, these strains were found to carry transferable resistance towards sulphonamides, trimethoprim and tetracyclines. An R plasmid of 25 MDa (IncU) was found to be identical to an R plasmid isolated from salmon with furunculosis caused by A. salmonicida ss salmonicida in farms in the same area in 1991.13

In Scottish Atlantic salmon farms, A. salmonicida isolates from 229 outbreaks of furunculosis in 44 units at 34 locations during 1988–90 were investigated for antibiotic resistance. Among 304 isolates, 55% were found to be resistant to tetracyclines, 37% resistant to oxolinic acid, 31% resistant to sulphonamides and 10% resistant to a combination of sulphonamides and trimethoprim.⁵¹ Among 40 oxytetracycline resistant isolates, 11 of the isolates transferred an R plasmid which encoded resistance to oxytetracycline and/or sulphonamides, trimethoprim and streptomycin to E. coli. This R plasmid was shown to be an IncU plasmid of the same type as found in Japan and Norway.52

In a study of 29 oxytetracycline resistant A. salmonicida isolates from Scotland, 19 transferred their tetracycline resistance to E. coli. ⁵² The Norwegian pRAS1 isolated from A. salmonicida were included in this study and restriction digests showed obvious similarity to the Scottish R plasmids, which were of similar size even if the featured resistance patterns were not identical. In another study, R plasmids featuring oxytetracycline resistance from mesophilic, motile Aeromonas spp. isolated from freshwater in a fish hatchery and from hospital sewage in England, were studied molecularly.⁴³ Six of 91 isolates from the fish hatchery water and 11 of 72 isolates from hospital sewage water were found to transfer oxytetracycline resistance. Seven of the 11 R plasmids from Aeromonas spp. from sewage were shown to belong to the IncU group.

In 23 drug-resistant A. salmonicida isolates from 13 different freshwater rainbow trout farms in Denmark, only three isolates transferred their R plasmid to E. coli. These three isolates transferred an R plasmid of 150 kb with resistance to oxytetracycline, sulphonamides, trimethoprim and streptomycin.⁴⁶ In addition, three oxytetracycline and sulphonamide resistant isolates of A. salmonicida from Canada and one oxytetracycline resistant isolate from USA, included as controls in the study, transferred R plasmids of 140–160 kb. Five A. salmonicida isolates from the Faroe Islands resistant towards oxytetracycline, sulphonamides, trimethoprim and streptomycin were included in the study and they transferred a 50 kb (probably IncU) plasmid to E. coli encoding resistance to all their drug resistance features except streptomycin.

IncU R plasmids were detected in drug-resistant atypical A. salmonicida isolates from farmed and wild fish on the Northeastern coasts of USA and Canada.53

The occurrence of a transferable R plasmid belonging to the IncUgroup in A. salmonicida isolates from various parts of the world in both freshwater systems and in the marine environment is remarkable. This plasmid was found to be identical in all the sampled locations except for the drug resistance region. The IncU plasmid is probably particularly successful at establishing in A. salmonicida. However, the IncU plasmid is promiscuous and was found in Aeromonas hydrophila (see later), in atypical A. salmonicida on the coast of Norway, on the northern part of the east coast of North America and in human enterobacteria in Eastern Europe. Hedges et al.⁴⁰ suggested that the homogenic IncU plasmids are characteristic of aeromonads but do occasionally transfer to and establish in other genera. The plasmids may acquire some of the genetic factors linked to drug resistance in the gene pools of these bacteria and subsequently bring these back to aeromonads. However, one should not rule out the opposite possibility, that these IncU plasmids may be bringing antibiotic resistance factors from aquatic environments into our antibiotic consuming environments.

The use of quinolones, oxolinic acid and flumequine in the control of bacterial infections in farmed fish from the 1980s resulted in the occurrence of A. salmonicida with reduced susceptibility to quinolones.54,55 Mutations in the gyrase A gene, gyrA, were found to be responsible for elevated MIC values against quinolones in clinical strains of A. salmonicida. ⁵⁶ A study of 12 clinical A. salmonicida isolates from French marine fish farms in the period 1998 to 2000 showed that all quinolone resistant isolates carried a point mutation in gyrA. 57

Quinolone resistant A. salmonicida isolates have been found to have changes in the outer membrane profile with loss of a 38.5 kDa protein and occurrence of a 37 kDa protein, probably linked to loss of porine function resulting in multiple low-level antibiotic resistance.58,59

In addition to amino acid substitutions in the gyrase A enzyme and porine changes in the outer membranes, it was indicated that an efflux mechanism might be involved in quinolone resistance in strains of A. salmonicida isolated from French marine fish farms.57

Quinolones, oxolinic acid and flumequine, were used extensively in fish farming to control infections caused by A. salmonicidafrom the late 1980s until effective vaccines containing oil adjuvants were introduced in the early 1990s. During that period, high MIC values for quinolones developed in isolates of A. salmonicida in all areas where furunculosis was endemic in salmon farming, resulting in repeated treatments of diseased fish during the summer months with only weeks between each treatment. In Norway, the first resistance to quinolones were discovered in 1989, about one year after fish farmers started using oxolinic acid to control furunculosis.⁵⁵ It was found that 36% of the isolates were resistant to one or more of the drugs tested, with 30% resistant to quinolones as the most widespread feature. After many years of effective vaccination, there is minimal information on the occurrence of antimicrobial resistance in strains of A. salmonicida in general. It has been shown that A. salmonicida share similar genetic tools worldwide when drug resistance evolves.

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1. One of the first evaluations of commercial products focused on a bacterial preparation called Biostart that is derived from Bacillus isolates. It was used during the production of cultured catfish studying the effect of inoculum concentration. In 1998, Moriarty reported that the use of commercial probiotic strains of Bacillus spp. increased the quality and viability of pond-raised shrimp.

2.The effect of Enterococcus faecium SF68 and Bacillus toyoi isolates present in Cernivet LBC and Toyocerin, respectively, to decrease the mortality of the European eel because of the edwardsielosis, ensuring greater efficiency with E. faecium SF68. It is relevant to note that E. faecium has long been known as a probiotic for humans, whereas B. toyoi has been used with terrestrial animals. Moreover, a B. subtilis strain combined with hydrolytic enzymes to produce Biogen, was used to supplement the feed of Oreochromis niloticus, obtaining significant increases in productivity.

3.The lactic acid-producing bacteria have been the focus of much interest. The human probiotic, Lactobacillus rhamnosus ATCC (American Type Culture Collection, Rockville, MD, USA), was used in rainbow trout for 51 days to reduce mortality by Aeromonas salmonicida, the causative agent of the fish disease “furunculosis” (one of the major fish diseases in many parts of world).

4.mixed cultures of bacteria (Bacillus subtilis, Lactobacillus acidophilus, and Clostridium butyricum) and yeast (Saccharomyces cerevisiae), enhanced nonspecific immune parameters of tilapia Oreochromis niloticus such as lysozyme activity, migration onf neutrophils, and plasma bactericidal activity, resulting in improvement of resistance to Edwardsiella tarda infection.

5. commercial products are available in liquid or powder presentations, and various technologies have been developed for improvement. on the case of fermentation processes, the interest has been focused on optimizing the fermentation conditions to increase the viability and functionality of probiotics, improving performance.

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Effects of probiotic Bacillus species in aquaculture

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Effects of probiotic Bacillus species in aquaculture

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EFFECTS OF PROBIOTIC BACILLUS SPECIES IN AQUACULTURE

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-- B. subtilis is a rod-shaped bacterium that typically forms small clumps, short chains, or single cells. It has a cell wall that is made of a complex molecule called peptidoglycan, which is made of long chains of glucose linked together by amino acids. Peptidoglycan surrounds the cell membrane and gives the bacterial cell shape and structure.

-- B. subtilis has a single circular chromosome that is located in the nucleoid region of the cytoplasm. Even though B. subtilis doesn't cause an interesting disease like anthrax, its chromosome does contain genes that produce useful antibiotics and compounds that can be used in bioremediation, which is a process that uses microorganisms to clean up the environment.

--B subtilis forms endospores, which are tough, dormant structures produced by some bacteria in a process called sporulation.

-- B. subtilis is a heterotrophic organism, which means it can't make its own food so it has to eat or consume something just like we do. B. subtilis absorbs its nutrients from the environment: those nutrients have to be converted into energy in some way.

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Prevent the ammonia generated by improve the number of nitrifying bacteria(Nitrobacter and Nitrosomonas)

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Prevent the ammonia generated by improve the number of nitrifying bacteria(Nitrobacter and Nitrosomonas)

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When you ask what is the greatest threatening of aquaculture’s farmer, perhaps if your fish know how to talk, i am sure the fish will say- Ammonia!!

What is ammonia? and why the rise and fall of  aquaculture industries highly dependable on effective control of ammonia.

Before I go into detail of those Nitrifying and denitrifying bacteria, let me give a short brief introduction of nitrogen cycle and water nitrification. If u want to be successful in aquaculture farming, you must understanding  a very importance concept – nitrogen cycle.

nitrogen cycle

Ammonification ——>Nitrification———>  Denitrification.

Ammonification. While traveling through sewer pipes, the majority of the nitrogen contained in raw sewage (urea and fecal material) is converted from organic nitrogen to ammonia through a process called hydrolysis, accomplished by putrefying bacteria and fungus. Technically, in the majority of situations, more ammonium than ammonia is created during ammonification.The actual ratio is influenced by pH and temperature.

Nitrification. The biological conversion of ammonium to nitrate nitrogen is called Nitrification. Nitrification is a two-step process. Bacteria known as Nitrosomonas convert ammonia and ammonium to nitrite. {2NH3 +3 O2 → 2HNO2 +2 H2O +158 kcal (660kJ). }

Next, bacteria called Nitrobacter finish the conversion of nitrite to nitrate. The reactions are generally coupled and proceed rapidly to the nitrate form; therefore, nitrite levels at any given time are usually low.        {HNO2 + 1/2 O2 = HNO3 – ⊿ G = 18 kcal. }
As we can see the above chemical equation, These bacteria known as “nitrifiers” are strict “aerobes,” meaning they must have free dissolved oxygen to perform their work. Nitrification occurs only under aerobic conditions at dissolved oxygen levels of 1.0 mg/L or more.

These two types of bacteria obtain the energy from the above oxidation process, but the energy utilization is not high, resulting in slow reproduction time. (i.e  more than 10 hours)

Today, people have not yet found a nitrification bacteria are able to directly convert the ammonia into nitrate!!

So to say, nitrification can only be completed by the combined effect of these two types of bacteria. We knew that the ammonia is harmful to human and fish, How about nitrite? Nitrite poisoning inhibits the uptake of oxygen by red blood cells – known as brown blood, eventually cause severe dealth in fresh water fish. Besides, nitrite can react with metal ions forming salt, and this salt tends to combine with amines, eventually forming a substance with strong carcinogenic effect- alkylene nitramine. Understanding the lethal effect of ammonia and nitrite residue, we have to manipulate the effectiveness of those beneficial bacteria, which in turn increases the efficiency of the nitrogen cycle.
Role of nitrifying bacteria in Aquaculture?

Nitrifying bacteria highly demand oxygen to survive, they love to stay in a variety of fiber cotton, glass rings (silicone made), ceramic microporous filter, where they will get a higher concentration of oxygen exchange. Here is a very important key note for those want to begin their aquaculture farming. The presence of toxic substances in the breeding pool, mainly ammonia and nitrous acid (nitrite), but thank God that this two toxic substances consumed by nitrifying bacteria, and generates a non-toxic nitrate, nitric acid where these substances can directly absorbed by water algae and plankton.

From the ecological point of view of the water, we cannot prevent the ammonia generated.

The more the loading of organic food, the more ammonia generated!!

But you can try to increase the number of nitrifying bacteria to consume the increasing ammonia in the water. Many people disregard the importance the issue, thinking that the more input of the food, the more fast growing of the fish, eventually resulting in losing tones of money.

So, what should we do to improve the number of nitrifying bacteria?

The first thing is we must get nitrifying bacteria a fundamental living bed.

Nitrifying bacteria tends to be attached to porous surface fixture, if placed in the pool water for its attachment, it can be quickly attached to the fixture surface and begin to proliferate. They are largely non-motile and must colonize a surface (gravel, sand, synthetic biomedia, etc.) for optimum growth. They secrete a sticky slime matrix which they use to attach themselves.
However, the placement of the fixtures in the pool water is usually not feasible, the reason is that this way may hinder the activities of the fish and is not conducive to fishing pond. More feasible approach is to place a bio ball in a external filtration system, act as breeding bed for nitrifying bacteria.

Denitrification. The biological reduction of nitrate (NO3) to nitrogen gas (N2) by facultative heterotrophic bacteria is called Denitrification. “Heterotrophic” bacteria need a carbon source as food to live. “Facultative” bacteria can get their oxygen by taking dissolved oxygen out of the water or by taking it off of nitrate molecules.

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https://www.tes.com/lessons/ZbJI-uYsTViGZw/minic-reflection-group-5