Abstract
A collection of lactic acid bacteria isolates from fish viscera was studied and investigated regarding to their functional properties and safety aspects. From these, three isolates GM1, GM2 and GM3 were identified as Enterococcus feacium species using molecular methods. Partial Amplified rDNA Restriction Analysis (partial ARDRA) with restriction enzyme HaeIII separated these isolates into distinctive group which suggest genotypic variability within enterococci strains isolated from fish viscera. The three strains GM1, GM2 and GM3 exhibited antimicrobial activity. Indeed strains have been shown to produce bacteriocins with inhibitory effect against food spoilage bacteria and pathogenic fish including Carnobacterium maltaromaticum. The molecular mass of bacteriocin, as calculated by tricine-SDS-PAGE, was found to be 4.5 kDa. All isolates were tested positive upon PCR amplification of enterocin A structural gene. Investigations of antibiotic resistance show that the isolates were mostly sensitive to several antibiotics (ampicillin, penicillin, tetracycline, gentamycine) and resistance to rifampicin. All isolates grow in esculin azide agar as a selective medium for enumeration of probiotic enterococci. This study suggests that our strains can be employed as probiotic or to improve the safety of food products.
Highlights
Enterococci belongs to the group of lactic acid bacteria (LAB) and are widely distributed in nature
This study suggests that our strains can be employed as probiotic or to improve the safety of food products
The genera comprise more than 30 species, but Enterococcus faecium and Enterococcus faecalis are the most prevalent species in foods 1-4
Summary
Enterococci belongs to the group of lactic acid bacteria (LAB) and are widely distributed in nature. Some enterococci are bacteriocinogenic and capable to inhibit the growth of certain pathogens and spoilage microorganisms, presenting a great potential in food preservation 2,5. It has been established that the intestinal microflora of fish is complex and that several species of LAB are part of the natural intestinal microflora of healthy fish 6. Enterococci have been isolated from the intestine of fish from integrated fish farming 7 and from shellfish 8. Processed fish products were often found to contain large numbers of LAB, enterococci. Salting processed fish during production may confer a selective advantage on enterococci because these bacteria are among the most tolerance to high salts concentrations 9
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