Selection and Characterization of Staphylococcus hominis subsp. hominis WiKim0113 Isolated from Kimchi as a Starter Culture for the Production of Natural Pre-converted Nitrite

Synthetic nitrite is considered an undesirable preservative for meat products; thus, controlling synthetic nitrite concentrations is important from the standpoint of food safety. We investigated 1,000 species of microorganisms from various kimchi preparations for their potential use as a starter culture for the production of nitrites. We used 16S rRNA gene sequence analysis to select a starter culture with excellent nitrite and nitric oxide productivity, which we subsequently identified as Staphylococcus hominis subspecies hominis WiKim0113. That starter culture was grown in NaCl (up to 9%; w/v) at 10℃-40℃; its optimum growth was observed at 30℃ at pH 4.0-10.0. It exhibited nonproteolytic activity and antibacterial activity against Clostridium perfringens, a bacterium that causes food poisoning symptoms. Analysis of Staphylococcus hominis subspecies hominis WiKim0113 with an API ZYM system did not reveal the presence of β-glucuronidase, and tests of the starter culture on 5% (v/v) sheep blood agar showed no hemolytic activity. Our results demonstrated the remarkable stability of coagulasenegative Staphylococcus hominis subspecies hominis WiKim0113, especially in strain negative for staphylococcal enterotoxins and sensitive to clinically relevant antibiotics. Moreover, Staphylococcus hominis subspecies hominis WiKim0113 exhibited a 45.5% conversion rate of nitrate to nitrite, with nitrate levels reduced to 25% after 36 h of culturing in the minimal medium supplemented with nitrate (200 ppm). The results clearly demonstrated the safety and utility of Staphylococcus hominis subspecies hominis WiKim0113, and therefore its suitability as a starter culture.