Comparison of three culture methods for the differentiation of Micrococcus and Staphylococcus in fermented squid shiokara

Abstract

SUMMARY: The accuracy in the differentiation between Micrococcus and Staphylococcus with three culture methods has been evaluated, using bacterial strains isolated from ika‐shiokara, a traditional Japanese fermented squid meat. A total of 530 strains of Gram‐positive, catalase‐positive cocci isolated from ika‐shiokara as well as the type strains of Micrococcus (eight strains) and Staphylococcus (26 strains) was differentiated with three culture methods using furazolidone‐peptone (FP) agar, Schleifer‐Krämer (SK) agar, and oxidation‐fermentation (OF) test of glucose. All the type strains of both genera used were clearly differentiated on FP agar, and well differentiated on SK agar with some exceptions, while only 46% of Staphylococcus could be identified correctly on the OF test. Among the 530 strains of Gram‐positive, catalase‐positive coccal isolates, 491 strains were identified as Staphylococcus on the FP & SK agar, while only 73 strains were identified as Staphylococcus on the OF test. To obtain detailed accuracy, 55 strains were randomly selected from the 530 strains and were further examined by DNA base composition (mol GC%) assay. The results on the FP & SK agar revealed 100% similarity with the results obtained by mol GC% assay, while the OF test of glucose revealed only 24% similarity with them. These results confirmed that OF test of glucose such as Baird‐Parker’s method is misleading method, which is still of relatively common use for differentiation of these two genera in food microbiological study. The simultaneous use of FP & SK agar was suggested to be useful in routine identification system in food microbiological study.

Review: Diversity of Microorganisms in Global Fermented Foods and Beverages

“…Preservation of fish through fermentation, sun/smoke drying and salting (Table 7 ) is traditionally practiced by people living nearby coastal regions, lakes, and rivers and is consumed as seasoning, condiments, and side dishes (Salampessy et al, 2010 ). Several species of bacteria and yeasts have been reported from fermented and traditionally preserved fish products of the world (Kobayashi et al, 2000a , b , c ; Wu et al, 2000 ; Thapa et al, 2004 , 2006 , 2007 ; Saithong et al, 2010 ; Hwanhlem et al, 2011 ; Romi et al, 2015 ).…”

The Microflora of Modern Ika-kurozukuri, Salted Squid with Ink and Liver

“…The microbial properties of traditional ika-shiokara and ika-kurozukuri were investigated in detail (Mori et al, 1979;Takai et al, 1992;Takai et al, 1993;Wu et al, 2000). At the beginning of fermentation, the major bacterial strains of both ika-shiokara and ika-kurozukuri were Micrococcus and Gram-positive rods.…”