Investigation on epizootic ulcerative syndrome and prophylactic measures in catfish heteropneustes fossilis

Abstract

The term probiotic has been defined as a mono or mixed culture of live microorganisms that when applied to animal or human, affect beneficially the host by improving the properties of the indigenous microflora . It is a collection of live cells of microorganisms that acts beneficially on host health, inhibits pathogens, enhances immunity and protects gut microflora (Fuller, 1989). The first trials of probiotics in aquaculture were conducted in Japan in 1981 (Gatesoupe, 2005). Decamp et al., (2006) reported that the probiotic application in aquaculture is an alternative way to the prophylactic use of antibiotics to control bacterial pathogens. The mode of action of the probiotics is rarely investigated, but possibilities include competitive exclusion, i.e. the probiotics actively inhibit the colonization of potential pathogens in the digestive tract by competition of nutrients and/or space, alteration of microbial metabolism, and by the stimulation of host immunity. Numerous microorganisms are used as probiotics in the field of aquaculture including a range of Lactobacillus sp, Lactococcus sp, Bifidobacterium sp, Pediococcus sp, Carnobacterium sp and Bacillus sp (Irianto and Austin, 2002). Many experiments on probiotics in aquaculture have focused on the addition of nonindigenous bacteria such as Bacillus sp to the diet. Bacillus was usually chosen because it is easy to grow and can be maintained in a viable state for long periods in the form of spores newline