• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.41-44
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• 2015

We reported an outbreak of clinical strangles in thoroughbred horses due to capnophilic Streptococcus equi subsp equi in South Korea. On three different farms, we isolated 17 S equi subsp equi isolates from 29 horses with or without abscesses in their lymph nodes. Of the 17 isolates, two isolates from clinical cases grew well in aerobic conditions, whereas 7/7 isolates from clinical cases and 8/22 isolates from the nasal discharges of horses did not. The latter 15 isolates were capnophilic, oxygen-sensitive, and $CO_2$-requiring S equi subsp equi, which could not grow in aerobic conditions, but which grew well in a $CO_2$ incubator with 5% $CO_2$, in anaerobic conditions using a GasPak, and with reduced oxygen tension in a candle jar. This study is the first report of a strangles outbreak caused by capnophilic S equi subsp equi in South Korea.

• Journal of Microbiology
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• v.43 no.1
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• pp.28-33
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• 2005

The purpose of this study was to develop a multipurpose incubator, without the gas cylinders (bottles) which are required for $H_2$ and $CO_2$ supplementation. In our bottle-free multipurpose incubator, the $H_2$ and $CO_2$ were generated by chemical reactions induced within the chamber. The reaction between sodium borohydride and acetic acid at a molar ratio of 1:1 was used to generate $H_2$, according to the following formula: $4NaBH_4+2CH_3COOH+7H_2O{\rightarrow} 2CH_3COONa+Na_2B_4O_7+16H_2$, whereas the other reaction, citric acid and sodium bicarbonate at a 1:1 molar ratio, was used to generate $CO_2$, according to the following formula: $C_6H_8O_7+3NaHCO_3{\rightarrow}Na_3(C_6H_5O_7)+3H_2O+3CO_2$. Five species of obligate anaerobic bacteria, one strain of capnophilic bacterium, and one strain of microaerophilic bacterium were successfully cultured in the presence of their respective suitable conditions, all of which were successfully generated by our bottle-free multipurpose incubator. We conclude that, due to its greater safety, versatility, and significantly lower operating costs, this bottle-free multipurpose incubator can be used for the production of fastidious bacterial cultures, and constitutes a favorable step above existing anaerobic incubators.

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.451-458
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• 2013

The human gastric pathogen Helicobacter pylori (Hp) has been considered a microaerophile. However, we recently reported that, when supplied with 10% $CO_2$, Hp growth is stimulated by an atmospheric level of $O_2$, suggesting that Hp is a capnophilic aerobe. In this study, we investigated the effects of aerobic $O_2$ tension on Hp cells by comparing gene expression profiles of cultures grown under microaerobic and aerobic conditions in the presence of 10% $CO_2$. The results showed that overall differences in gene expression in Hp cells grown under the two $O_2$ conditions were predominantly growth-phase-dependent. At 6 h, numerous genes were down-regulated under the aerobic condition, accounting for our previous observation that Hp growth was retarded under this condition. At 36 h, however, diverse groups of genes involved in energy metabolism, cellular processes, transport, and cell envelope synthesis were highly up- or down-regulated under the aerobic condition, indicating a progression of the cultures from the log phase to the stationary phase. The expression of several oxidative stress-associated genes including tagD, katA, and rocF was induced in response to aerobic $O_2$ level, whereas trxA, trxB, and ahpC remained unchanged. Altogether, these data demonstrate that aerobic $O_2$ tension is not detrimental to Hp cells but stimulates Hp growth, supporting our previous finding that Hp may be an aerobic bacterium that requires a high $CO_2$ level for its growth.