碳氮营养和培养条件对芽孢杆菌(Bacillus sp.) A4生长的影响

芽孢杆菌(Bacillus sp.) A4是一株具有溶甲藻能力的菌株，为探究营养条件与培养条件对A4生长的影响，明确在多因素共同作用下菌株的生长特性，先以单因素方法比较不同碳、氮营养因子对其生长的影响，再以Plackett-Burman方法综合比较碳源、氮源、pH、接种菌量、温度、转速、装液量等因子对其生长的协同影响效应。结果显示，A4菌对有机碳源玉米浆和有机氮源大豆蛋白利用效果最好，培养24 h后菌量分别达到3.58×108、3.19×108 CFU/ml。各因子的重要性排序依次为大豆蛋白、温度、玉米浆、转速、接种菌量、pH、装液量，且大豆蛋白和温度对A4菌的生长影响显著(P<0.05)。研究表明，培养条件对菌株生长调控也有重要意义，在评估相关因素对菌株生长或生态功能的影响时，须将营养条件和培养条件协同分析。

The Effects of Different Carbon and Nitrogen Nutrients and Culture Conditions on the Growth of Bacillus sp. Strain A4

In this study, we explored how the nutritional and culture conditions affected the growth of a Bacillus sp. strain A4 and identified the growth characteristics of this strain during the multi-factor interaction. We first applied the single factor test to study the effects of different carbon and nitrogen sources, and then employed Plackett-Burman (PB) test to evaluate the effects of seven factors including carbon source, nitrogen source, pH value, inoculation amount, temperature, rotation speed and liquid volume in the flask. The results showed that the absorption efficiencies of strain A4 for different carbon and nitrogen sources were different. We found that the corn steep liquor was the best carbon source for strain A4, and that the soybean protein was the best nitrogen source. When cultured with the corn steep liquor or the soybean protein for 24 h, the amounts of bacteria reached 3.58×108 CFU/ml and 3.19×108 CFU/ml respectively. The results of Plackett-Burman (PB) test showed that the order of factors affecting the growth of strain A4 as soybean protein> temperature>corn steep liquor>rotation speed>inoculation amount>pH value>liquid volume in the flask. Moreover, the soybean protein as the nutritional factor and the temperature as the culture condition both had significant effects on the growth of strain A4 (P<0.05). Temperature had a greater effect on the growth of strain A4 than the corn liquid factor. The results above indicated that the culture conditions played a vital role in the growth regulation of the bacteria. We also recommend that it should be essential to associate the nutritional factors with the culture conditions when evaluating the effects of related factors on the growth or ecological function of bacteria.