Phenotypic and technological properties of Leuconostoc mesenteroides O157:H7 isolated from soybean cake (okara)

Lactic acid bacteria (LAB) are microorganisms that produce lactic acid as a by-product during metabolic activities. This work aimed to phenotypically and technologically characterize the Leuconostoc mesenteroides strain, among other presumptive LAB strains isolated from soybean cake (okara). Okara is a solid waste resulting from sieving during the production of soymilk. The isolate was subjected to morphological, biochemical, and technological tests during characterization. The morphological and biochemical tests revealed that the isolate was presumptively, a lactic acid bacterium, Leuconostoc mesenteroides. Technological properties of the isolate showed capability for starch hydrolysis, indicating the potential of the isolate to improve flavour and texture of fermented foods if applied as a starter culture. Although the isolate could not hydrolyse arginine, it showed a positive indication for lipase activity which may also contribute to flavour development in fermented foods. Furthermore, the isolate showed negative haemolytic activity hence, non-virulent. The isolate was assessed for its ability to aggregate with pathogens; Vibrio parahemolyticus, Staphylococcus aureus, and Escherichia coli O157: H7 and possibly inhibit them. The result ranged from 57.42% (Staphylococcus aureus) to 78.62% (Escherichia coli 0157). The isolate also showed Autoaggregation of 57.20 % which means that it also has a strong aggregation ability.