The use of anti-biotics in the aquaculture industry has been widespread and beneficial- but it has now progressed to overuse. Injudicious use of antibiotics in aquatic animals has led to antibiotic resistance. This was specially felt in the shrimp culture industry, where massive increase in production, massive overcrowding and unrestricted use of antibiotics led to emergence of anti-biotic resistant bacteria. This has, in turn, led to production crashes and losses to farmers engaged in aquaculture.
But the problem doesn’t end here. Antibiotic resistance on aquaculture farms could lead to problems for human health. Studies show that resistant genes can be transferred between bacteria. It means that a resistant bacterial strain originating on a fish farm could transfer plasmids to a strain causing communicable diseases in humans.
This has led governments in Europe and US to restrict the use of antibiotics in aquatic animals. Asian countries have comparatively less stringent rules, especially regarding overuse of an antibiotic called Chloramphenicol.
Nowadays, the use of probiotics is gaining popularity in aquaculture. In lay language, probiotic means a microbial supplement which benefits host animal by improving their intestinal microbial balance. Oday, probiotics are used as therapeutic, prophylactic and growth promoting agents in rearing aquatic animals.
Widenly researched for use as aqua probiotics are Lactic Acid Antibiotics like lactobacillus and bifidobacteria. Other strains are the Bacillus species, and yeasts.
Verschuere defines probiotics as: a microbial adjunct having a beneficial effect on host, by modifying the host associated or ambient microbial community, ensuring improved use of feed or increasing its nutritional values, enchancing host response towards disease or improving ambient surroundings.
Probiotics act in several ways:
Inhibiting pathogens by producing antagonistic compounds
Competing with pathogens for attachment sites.
Alteration of enzymatic activity of pathogens
Nutritional benefits like improving feed digestibility and utilization.