Techno-functional traits and safety aspects of coagulase-negative Staphylococcus saprophyticus isolated from traditional fermented food

Abstract

Ngari is a traditional-fermented fish food product of northeast India from which distinct bacteria were initially isolated and assessed for their antagonistic activities against wide spectrum of foodborne and enteric infection-causing pathogens. Among them, Staphylococcus saprophyticus strain AAS1 showed strong inhibitory activity against all the indicator pathogens, ranging from 81.14 ± 2.4 to 340.18 ± 2.1 AU/mL. In vitro techno-functional properties of strain AAS1 were further evaluated and confirmed by using standard methodologies. The AASI strain exhibited high tolerance at higher acidic conditions, simulated gastric juice of pH 2.0, and oxgall (0.5%, w/v). Furthermore, this strain showed noticeable hydrophobicity and auto-aggregation traits of 64.2 ± 1.3 and 44.3 ± 1.5%, respectively. The isolate depicted not only resistance to phenol and lysozyme but also exhibited 2,2-diphenyl-1-picrylhydrazyl degradation (16.6 ± 1.2–67.5 ± 1.1%), hydrogen peroxide tolerance (2.1 ± 0.04–1.1 ± 0.04), and hydroxyl radical scavenging (10.6 ± 1.2–57.5 ± 1.1%) properties. Strain AAS1 fermented varied carbohydrates and produced exopolysaccharide and lipase. The isolate exhibited significant rate of autolysis (48.6 ± 1.2%), catalase activity (18.14 ± 0.3 AU), and nitrate reductase production (26.32 ± 0.8 mM nitrite/mg dry weight). It has also showed negative results toward in vitro hemolytic, DNase, gelatinase, and biofilm formation tests, in addition to being susceptible to conventional antibiotics used. In a nutshell, strain AAS1 may be employed as quintessential candidate for its disparate applications in food and pharmaceutical industries if its probiotic function can be validated.