两阶段pH和搅拌控制策略提高哈茨木霉产β-1，3-葡聚糖内切酶

为提高哈茨木霉（Trichoderma harzianum GIM 3.442）发酵生产β-1，3-葡聚糖内切酶的酶活Eendo及其内切酶酶活在总酶活中所占的比例Eendo/Etotal，在7 L发酵罐水平考察了不同pH和搅拌转速对菌体和产酶的影响。结果表明，单一pH或搅拌转速的优化不能使菌体生长和产物合成同时达到最优效果。通过分析不同pH和转速下发酵曲线和动力学参数，提出了两阶段pH和搅拌转速控制策略：在发酵前期（0~24 h）控制pH 7.0，搅拌转速100 r/min，发酵后期（24~168 h）控制pH 5.0，搅拌转速200 r/min。β-1，3-葡聚糖内切酶（Eendo）、酶合成生产强度（QE，endo）和Eendo/Etotal分别达到了407.8 U/mL、3.09 U/（mL?h）和0.71，比优化前分别提高了320.0%、398.4%和65.1%。
Beta-1，3-endoglucanase has important applications in food，agriculture and biotechnology. To enhance the productivity of β-1，3-endoglucanase and its ratio in total β-1，3-glucanase activity by Trichoderma harzianum Rifai GIM 3.442，the effects of pH and agitation speeds were investigated in a 7 L fermentator. It was shown that the mono-control of pH or agitation speed could not satisfactorily offer higher biomass and β-1，3-endoglucanase production simultaneously. A two-stage pH and agitation speed control strategy was therefore employed，i.e.，pH and agitation speed were controlled at 7.0 and 100 r/min in the first stage of fermentation（0~24 h） and then switched to pH 5.0 and 200 r/min in the second stage（24~168 h）. On account of this， β-1，3-endoglucanase activity and its productivity reached 407.8 U/mL and 3.09 U/（mL?h），320.0 % and 398.4 % higher than that of uncontrolled condition，respectively. The ratio of β-1，3-endoglucanase to total β-glucanases activity was 0.71，increasing 65.1 % than that of uncontrolled condition