Optimization of cultural conditions for thermostable β-1, 3-1, 4-glucanase production byBacillus subtilis ZJF-1A5

The optimization of cultural conditions for β-glucanase production byBacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had great effect on β-glucanase production which maximized at optimal temperature of 37°C and decreased significantly when temperature was over 37°C. Charge quantity affected β-glucanase production significantly. Adding oxygen vector N-dodecane or acetic ether benefited β-glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β-glucanase production and the cultivation time span to reach the highest β-glucanase activity. The optimal cultural conditions for β-glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82% (v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37°C for 50 h. Repeated experimental results accorded with those predicted by a second-order polynomial model. The amount of β-glucanase, α-amylase and neutral protease produced byB subtilis ZJF-1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase. Project (No. B0608) supported by the National Natural Science Foundation of China and a grant (2001121B25) from Hangzhou Science and Technology Development Project of Zhejiang Province, China     

Bullying and racism among Asian schoolchildren in Britain

Previous research on school bullying has largely neglected the issue of racism, and where it has been studied, the methods used have been unconvincing. The result is that little is known about bullying among ethnic minority children in British schools.This paper describes a questionnaire survey of 243 Hindu, Indian Muslim and Pakistani children attending temples and mosques in the Preston and Bolton area of Lancashire, asking about their experiences of school bullying, who bullied them and in what way. Results show that bullying was widespread (57 per cent of boys and 43 per cent of girls had been bullied that school term), and that all three ethnic groups suffered equally. However, bullying was at least as likely to be by other Asian children of a different ethnic group as it was by white children, and it was likely to relate to some religious or cultural difference such as the animal forms of some Hindu Gods, the clothingworn by Indian Muslims or the language spoken by Pakistanis. Bullying between members of the same ethnic group was comparatively rare, although a number of Hindu children reported insults relating to the caste system. It is concluded that, although it is difficult to generalize from such an unrepresentative sample, bullying among ethnic minority children is clearly a rich and complex problem that merits further study.     

碘、溴和叠氮化物水溶液中的声化学反应

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