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Staphylococcus aureus is a major causative agent leading to bovine mastitis and has specific phonotypical characteristics including small colony, slow growth, and decreased hemolysis, therefore named as the small colony variants (SCVs). Out of 30 tested samples of the chronic S. aureus cases, one strain of SCVs (S. aureus SCV22) was isolated along with its parental strains (S. aureus11). S. aureus SCV22 showed a slow growth rate when it is compared with the parental strain. However, their resistant patterns were similar. Meanwhile, S. aureus SCV22 depicted the lower rate of apoptosis in bovine mammary epithelial cells. These findings of the present study presented the unique characteristics of S. aureus SCV22 for the first time in Yunnan province, which provided a prophase foundation for further study about the pathogenesis of S. aureus SCVs in chronic mastitis.

The transgenic cotton expressing chitinase and glucanase genes was studied using nontransgenic cotton as a control. Specifically, the effects of exogenous genes on bacterial community diversity in rhizospheres of cotton at stages of seedling, budding, boll forming and boll opening were evaluated through comparing the number of cultivable bacteria and analyzing 16S rRNA gene clone libraries. The results showed that the number of cultivable bacteria was not affected by exogenous genes but the cotton growth period, and the number peaked at the stage of boll forming with vigorous metabolism. The 16S rRNA gene clone library prepared from soil bacteria in rhizospheres of transgenic and nontransgenic cotton at different stages contained 2400 clones which covered 283 genera. Among them, Acidobacterium was the most dominant group which contained 642 clones, followed by unclassified bacterium and Flavisolibacter. Compared with nontransgenic cotton, the rhizosphere bacterial diversity of transgenic cotton exhibited lower level at the same growth stage, however, their common bacterial communities increased with growth and development. Our results suggest that chitinase and glucanase genes decrease the rhizosphere bacterial diversity at distinct degrees, however, the difference of bacterial diversity between transgenic and nontransgenic cotton reduces gradually with the extension of cultivation period.