Screening of probiotics activities of lactobacilli strains isolated from black tiger shrimp (Penaeus monodon)

Abstract

The objective of this study was to characterize probiotic Lactobacillus spp. isolated from black tiger shrimp (Penaeus monodon) focusing on their safety, antimicrobial and antibiotic susceptibility properties. Sixteen colonies of lactobacilli isolated from ten samples of shrimp were screened for their probiotic use. These isolates were identified and characterized on the basis of their morphological and biochemical test results. The IMViC, Catalase, Oxidase test status of selected isolates showed that these isolates were identified as Lactobacillus spp. Four isolates of lactobacilli were selected for acid and bile tolerance. These isolated strains were assayed for their susceptibility to twelve antibiotics such as ampicillin, penicillin G, gentamicin, tetracycline, erythromycin, vancomycin, neomycin, chloramphenicol, kanamycin, ciprofloxacin, doxycycline & nalidixic acid using the agar overlay disk diffusion method. Isolate-1 and Isolate-2 were resistance to five antibiotics among twelve antibiotics used. All the isolates were resistance to gentamicin, and ciprofloxacin but susceptible to ampicillin, tetracycline, erythromycin and chloramphenicol. For determination of antimicrobial activity, all the isolates were assayed against eight pathogenic test organisms using agar well diffusion method. Three isolates showed to inhibit all the test organisms though they vary in zone of inhibition diameter. The highest zone of inhibition was observed by isolate-1 against E. faecalis (19 mm), isolate-2 against E. coli (20mm) and isolate-4 against Bacillus subtilis (14 mm). All the isolates showed lowest activity against B. megaterium and S. aureus. A substantial zone of inhibition was found against E. coli & E. faecalis, which adds further support to the suggestion that the probiotic strain could help prevent intestinal infection. This study suggested that the indigenous microflora of shrimp itself is a potential source of probiotics.