Antimicrobial Action and Biopreservation by Autochthonous Lactic Acid Bacteria of Fish

Abstract

The purpose of this research was to assess native Lactic Acid Bacteria (LAB) for antimicrobial activities in relation to fish preservation. LAB were isolated from intestine of Oreochromis sp. Listeria monocytogenes, being a big microbial hazard of fresh as well as preserved fish food, was chosen against LAB antimicrobials. In the present study sixteen LAB like isolates from fish intestine were judged for their anti-listeria activities by agar well diffusion assay. Thirteen of them were antagonized Listeria monocytogenes (ATCC 657) by creating inhibition zone in nutrient agar plate. Antagonistic activities with inhibitory zones but not with growth circles clearly marked that inhibition was due to antimicrobials but not for competitive exclusion. LAB like bacteria in different forms like live cells, cell-free supernatant, alkaline cell-free supernatant and heated cell-free supernatant conferred antibacterial activities. No acid and hydrogen peroxide inhibition was reported. Except few, most of the alkaline and catalase treated culture supernatant when being heated to 90ºC exhibited strong antagonism against the pathogenic strain. Susceptibility of Listeria monocytogenes to LAB antimicrobials seemed to be caused by both thermostable and thermolabile compounds and could be practiced in fisheries industry for food hygiene and also as biopreservatives.

Native Antimicrobials of Tilapia (Oreochromis sp.) Against Pathogenic Gramnegative Bacteria

“…(a) To eliminate the effect of organic acids, pH of the filtered CFS was changed using 1(M) NaOH solution (Udhayashree et al, 2012;Rammelsberg and Radler, 1990;Sanyal and Chatterjee, 2021) and then inhibitory activity of that alkaline CFS (ACFS, pH 7.5) was analyzed against the indicator strains by standard well diffusion method.…”

“…(b) The alkaline CFS was treated with catalase (2 mg/ml) (ACCFS) (Jini et al, 2011;Sanyal and Chatterjee, 2021) and evaluated further for antimicrobial activity to get rid of the effect of H2O2.…”

“…(c) Effect of heat treatment: To examine the thermo stability of the inhibitory substances alkaline and catalase treated CFS was incubated at 90°C for 10 min (Složilová et al, 2014;Sanyal and Chatterjee, 2021) and then the residual antimicrobial activity of that CFS (HACCFS) was assayed by the well diffusion method against test pathogens.…”

Antimicrobial Impacts of Microbial Metabolites on the Preservation of Fish and Fishery Products: A Review with Current Knowledge

“…In this context, sixteen LAB were isolated from the intestine of Oreochromis spp. and investigated for their anti-listeria activity [145]. Among the sixteen isolates, thirteen isolates showed an inhibitory zone on the agar plate inoculated with Listeria monocytogens.…”

“…Furthermore, these microbial isolates were tested in their different forms, including live cells, cell-free supernatant (CFS), alkaline CFS, and heated CFS against L. monocytogens. The results indicated that anti-listeria activities occurred by both heat-stable and sensitive compounds, as well as in live cells [145]. Wiernasz et al [16] investigated six different LAB cultures for the biopreservation of salmon gravlax during 25 days of storage at 8 • C using vacuum packaging.…”