Aquaculture is one of the fastest emerging food producing sectors of the world. Probiotics are used in aquaculture to improve growth performance nutrition decrease diseases and develop immune system. Some bacterial, fungal strains can be blended with feeding pellets or by encapsulating into live feed stock or administered orally.
Introduction
Aquaculture is one of the fastest emerging food producing sectors of the world. World aquaculture has immensely grown during the last few years as well as becoming an economically significant zone.
Probiotics
Probiotics shows a new dimension in disease resistance and improving water quality in aquaculture industry. The Greek word probiotic means “for life”, was introduced by Parker et al. According to him, probiotics are “Organisms and substance, which contribute to intestinal and microbial balance”. Fuller, et al defined probiotics as “live microbial feed supplement which beneficially affect the host animal by improving its intestinal microbial balance”. Probiotics are used in aquaculture to improve growth performance nutrition decrease diseases and develop immune system
Micro Organisms of Probiotics
Research shows that Lactic Acid Bacteria have been broadly used as probiotic strains which are usually present in the intestine of healthy fishes such as the Lactobacilli and Bifidobacterium. Some gram-positive bacteria like Bacillus, Enterococcus, Streptococcus act as common probiotic strains which are the main gastrointestinal microbiota.
Types of Probiotics
Probiotics are two types namely feed probiotics and water probiotics
Feed probiotics
Some bacterial, fungal strains can be blended with feeding pellets or by encapsulating into live feed stock or administered orally to feed rearing animals to prevent disease and enhance essential microbial flora of the gut.
Water Probiotics
Water probiotics are applied to reduce organic pollutants and various contaminants in water by directly applying to rearing medium. These improve water quality by converting organic matter to smaller units. Breakdown of organic matters evolve simpler substances like glucose and amino acids that are used as food for beneficial bacteria which reduce the accumulation of organic pressure and provide congenial environment to farmed stock. Probiotic bacteria such as Bacillus sp.
Significance of Probiotics in Aquaculture
Probiotics use in aquaculture show great impact on aquatic organisms. Probiotics decrease accumulation of organic load and maintain water quality in an efficient way.
Improvement of water quality
According to Michael et al, the contamination of various nitrogenous compounds such as ammonia, nitrite and nitrate has been a serious problem in aquaculture system. Ma et al, described that Lactobacillus sp. simultaneously eliminates nitrogen and pathogens from polluted shrimp farms. The aerobic gram-positive bacteria, such as Bacillus sps. Aquatic pathogens are able to grow and proliferate in the environment, as they benefit from high organic matter loading, which is primarily derived from feed, feces and phytoplankton.
Fig 1: Nitrogen cycle
Control of Diseases
The important role of probiotics in aquaculture is increasing. This is primarily due to disease, which represents the biggest constraint in aquaculture, and is a huge challenge for future growth and expansion.
In order to effectively manage disease, three factors must be considered:
If a probiotic bacterium is able to colonize the intestine, at least temporarily, by adhering and growing within the intestinal mucus and mucosa, it can reduce the available receptor sites for pathogens and stimulate their removal from infected regions. This mechanism is called competitive exclusion.
Fig:3 Microscopic pictures of bacterial strains
Vibrio control in Aquaculture
The use of probiotics in aquaculture to improve pond environment and control Vibrio populations has been one of the most common strategies used by farmers to fight EMS outbreaks.
An effective aquaculture probiotic which can colonize the gut has two benefits:
If a probiotic bacterium is able to colonize the intestine, at least temporarily, by adhering and growing within the intestinal mucus and mucosa, it can reduce the available receptor sites for pathogens and stimulate their removal from infected regions. This mechanism is called competitive exclusion.
By attaching to different receptors, probiotics are able to interact with the host immune system. Many studies have investigated the effect of probiotics on the immune system in fish and shrimp, focusing on both the innate and adaptive immune response as well as the localized (i.e., intestine) and systemic (whole organism) response.
Bacillus as probiotics for finfish and shellfish
Use of Bacillus as probiotics species like B. subtilis, B. velezensis, Bacillus amyloliquefaciens, Bacillus circulans, Bacillus thuringiensis, Bacillus aerius increased resistance of finfish and shrimp to pathogenic bacteria including Streptococcus, Aeromonas Vibrio, Enterococcus and Lactococcus, Bacillus species are also a natural resource for screening new quorum quenching bacteria and are commonly regarded as safe bacteria for the use in aquaculture (e.g.Aquacare control, Skretting) as agents for improving water quality and disease control. . It has been demonstrated that use of Bacillus probiotics as the bioremediatory tools in the rearing water of aquaculture species and soil of aquaculture ponds have been exhibited as a feasible way of improving water quality in Bacillus subtilis, B. licheniformis, B. cereus and B. coagulans are suggested as suitable bioremediatory tools for removing of organic waste and Bacillus subtilis and B. licheniformis are suggested as more suitable candidates for bioremediation of aquaculture.
Fig :4 Bacillus role in aquaculture
About AquaCare Control
AquaCare control harbours bacterial strains of live Bacillus Sps in lyophilized form and does not need fermentation. It degrades the organic material such as Faecal matter, unused feed, and sludge as well as it also controls ammonia by bacterial de-nitrification process. Moreover, Aqua care Bacillus strains also reduces the vibrio Sps by bacterial synergism so aqua care control regarded as a highly efficient probiotic in Aqua culture.
Conclusion
In recent years, probiotics, prebiotics have become an essential part of the aquaculture practices for improving the growth performance and disease resistance. Probiotics play an important role in feed conversion, growth rates, weight gain, immune response and disease resistance of shrimp and fish. On the other hand, prebiotics also have various beneficial effects mainly in disease resistance and nutrient availability of aquatic species. the combined application of probiotics and prebiotics, which improve the survival and establishment of the live microbial dietary supplement in the gastrointestinal tract of the host.
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