Evaluation of Methodologies for the Isolation of Bioprotectives Cultures of Lactic Acid Bacteria from Aquaculture, Mediterranean Fish Species

Introduction:  The development of biopreservation techniques in fishery products has increased, in recent years, with the main objectives being increased the shelf life and reducing the addition of chemical preservatives. Lactic acid bacteria are the main microbial group able to produce inhibition of pathogenic species. However, isolation methods of inhibitory strains should be further studied to propose alternatives for optimizing their efficiency.

Purpose:  The aim of this work was to develop a suitable method for the obtaining bioproptective cultures of lactic acid bacteria in marine, aquaculture fish species.

Methods:  For this purpose, different lots of sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were collected from an estuary located in Ayamonte (Huelva). The inhibitory capacity was tested against a cocktail of strains.

Results:  The present work showed that enrichment of samples in MRS and in buffered peptone water produced an improved recovery of bacteria with inhibitory potential. Moreover, the results showed a stronger and more heterogeneous inhibition against Salmonella sp. than for L. monocytogenes; since halo diameters showed statistically significant differences. This could be attributed to the increased susceptibility of Salmonella sp. against the growth of lactic acid bacteria, producing greater variability in cell viability.

Significance:   This study can be a starting point for future work in searching for improved conditions for the isolation and identification of microbial cultures with high inhibitory potential; thus, providing this outcome to food industries.