Effect of lactobacillus rhamnosus cells against specific and native fish spoilage bacteria and their spoilage indices on Asian seabass fish chunks

Abstract

Aim : The present study aimed at evaluating probiotic bacterial cells, Lb. rhamnosus by coating on seabass fish meat chunks against its spoilage indices,native and specific fish spoilage bacteria. Methodology : Seabass fish fillets were cut into chunks, washed and taken into petri plates. Scores were made using sterile blade. Lb. rhamnosus cells were coated on the chunks using micro pipette and tested for antagonism against fish-borne specific spoilage bacteria such as Shewanella putrefaciens and Pseudomonas fluorescens through "Deferred antagonism assay". Spent culture of Lb. rhamnosus was assayed for antagonism through "Agar-well diffusion assay". The changes were estimated for two days following "Conway micro diffusion" method. Results : Lb. rhamnosus cells when co-cultured with P. fluorescens were inhibited on the second day by 1.0 log difference as compared with control. The spent culture of Lb.rhamnosus, after treating at 121°C for 10 min showed inhibition against P. fluorescens. But the spent culture after treatment at 100°C showed difference of inhibitory zone at 5.0 mm against S. putrefaciens. Lb. rhamnosus cells when coated on seabass fish meat chunks, the native proteolytic bacteria was inhibited by Lb. rhamnosus on 3rd day by 1.3 log difference as compared to control. Lb. rhamnosus cell coat, reduced fish spoilage indices such as Trimethylamine- Nitrogen (TMA-N) and Total volatile bases- Nitrogen (TVB-N) by 80 mg% difference. Interpretation : The study concluded that coating of probiotic Lb. rhamnosus cells on fish meat would contribute antagonism and regulate the growth of specific and native spoilage bacteria with spoilage indices.