• Journal of Microbiology and Biotechnology
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• v.32 no.4
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• pp.458-463
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• 2022

We evaluated the antibiotic susceptibilities, hemolytic activities, and technological properties of 36 Staphylococcus xylosus strains and 49 S. pseudoxylosus strains predominantly isolated from fermented soybean foods from Korea. Most of the strains were sensitive to chloramphenicol, erythromycin, gentamycin, kanamycin, lincomycin, oxacillin, tetracycline, and trimethoprim. However, 23 strains exhibited potential phenotypic acquired resistance to erythromycin, lincomycin, and tetracycline. Based on breakpoint values for staphylococci from the Clinical and Laboratory Standards Institute, >30% of the isolates were resistant to ampicillin and penicillin G, but the population distributions in minimum inhibitory concentration tests were clearly different from those expected for acquired resistance. None of the strains exhibited clear α- or β-hemolytic activity. S. xylosus and S. pseudoxylosus exhibited salt tolerance on agar medium containing 20% and 22% (w/v) NaCl, respectively. S. xylosus and S. pseudoxylosus strains possessed protease and lipase activities, which were affected by the NaCl concentration. Protease activity of S. pseudoxylosus was strain-specific, but lipase activity might be a characteristic of both species. This study confirms the potential of both species for use in high-salt soybean fermentation, but the safety and technological properties of strains must be determined to select suitable starter candidates.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.93-98
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• 2023

Nuruk is a starter culture of Korea manufactured by spontaneous fermentation of grains. We isolated bacteria of the genera Bacillus and Staphylococcus, and lactic acid bacteria (LAB) from eight commercial nuruk samples collected from four districts of Korea using selective agar media and identified them based current taxonomic standards. Bacillus was detected in all samples, but Staphylococcus or LAB were not detected in three samples. In seven samples, except one sample scored the highest cell number of LAB, Bacillus and Staphylococcus were counted as the highest and the lowest numbers, respectively. Six species of Bacillus were identified, and B. subtilis, B. velezensis, and B. licheniformis were predominant species. Nine species of coagulase-negative Staphylococcus were identified, and the predominance of S. pseudoxylosus and S. saprophyticus was confirmed. Ten species of LAB including Enterococcus, Lactobacillus and close relatives, Pediococcus, and Weissella were identified. P. pentosaceus was identified as the predominant species.