Isolation of lactobacillus spp. from various shellfish

초록

Recently, it has been announced that the use of antibiotics common for man and animal will be banned in animal feeding. To develop aquaculture feed adjuvant substituting antibiotics we have isolated 127 strains of tentative Lactobacillus spp. from four species of shellfish – oyster(Crassostrea gigas), short-neck clam(Ruditapes philippinarum), spiny top shell(Batillus cornutus) and mussel(Mytilus edulis). Initially, shellfish samples were grounded and serially diluted prior to being plates onto Rogosa medium whish is known to be selective for Lactobacillus spp. Resulting colonies were first tested for their catalase activity which is absent in Lactobacillus spp. Subsequently, catalase negative colonies were examined microscopically whether they were Gram-positive. A total of 127 catalase negative and Gram-positive isolates were collected and numbered accordingly. Majority of isolates 83/127 (65%) were isolated from oyster. Molecular identification of each strain by PCR-RFLP(polymerase chain reaction – restriction fragment length polymorphism), SDS-PAGE and 16S rDNA sequencing is now in progress. In further studies, we will select several strains with increased resistant to a variety of environmental stresses. The selected strains can be used as microbial feed adjuvant for aquaculture.