本试验旨在优化豆粕米曲霉（Aspergillus oryzae）固体发酵条件，使豆粕中的植酸降解到最低水平且发酵菌种的生物量达到最大值，同时了解植酸降解和发酵菌种生物量增长的相关性。采用Box-Behnken设计的响应面法来优化料水比、接种量和发酵时间，试验共设17组，共5个发酵条件，每个发酵条件设3个水平（料水比分别为0.5、1.0和1.5，接种量为分别4%、8%和12%，发酵时间分别为72、96和120 h），中心点设5个重复，豆粕中的发酵菌种生物量由麦角固醇含量进行估算。结果表明豆粕中植酸含量最低值为2.38 mg/g干物质，此时料水比为0.5,接种量为4%,发酵时间为120 h；豆粕中麦角固醇含量最高值为396.74 mg/kg干物质，此时料水比0.5，接种量为12%，发酵时间为120 h。此外，豆粕中植酸降解和发酵菌种生物量增长具有显著的负相关性。结果表明，米曲霉固体发酵豆粕时植酸降解的最佳条件为：料水比0.5,接种量4%,发酵时间120 h；固体发酵时米曲霉生长所需的最佳条件为：料水比0.5,接种量12%,发酵时间120 h；米曲霉是一种高效的植酸降解菌种，具有应用于大规模豆粕发酵的潜力；麦角固醇含量的变化可以反映出固体发酵过程中植酸降解或植酸酶生成量的变化。

The aim of the present study was to optimize the solid-state fermentation with Aspergillus oryzae to degrade phytic acid and increase Aspergillus oryzae biomass growth in soybean meal, and to investigate the correlation between phytic degradation and fungal biomass growth. The response surface methodology by Box-Behnken design was used to optimize the ratio of substrate to water, inoculum size and duration. A total of 17 runs including 5 fermentation conditions and 5 replicates at the center point were set in this experiment. Each fermentation condition consisted of 3 levels (the ratios of substrate to water were 0.5, 1.0 and 1.5, inoculum sizes were 4%, 8% and 12%, and durations were 72, 96 and 120 h). Ergosterol was used as a tool to estimate Aspergillus oryzae biomass. The results showed that the minimum phytic acid content was 2.38 mg/g dry matter (DM) when the ratio of substrate to water was 0.5, inoculum size was 4% and fermentation duration was 120 h. The maximum ergosterol content was 396.74 mg/kg DM when the ratio of substrate to water was 0.5, inoculum size was 12% and duration was 120 h. In additoin, a significant negative correlation between phytic acid degradation and fungal biomass growth of substrate in solid-state fermentation was detected. In conclusion, the optimal conditions for phytic acid degration can be achieved when the ratio of substrate to water is 0.5, inoculum size is 4% and duration is 120 h, and the optimal conditions for Aspergillus oryzae growth can be achieved when the ratio of substrate to water is 0.5, inoculum size is 12% and duration is 120 h. Aspergillus oryzae is of high efficiency in phytic acid degradation, and shows a potential use in industry-scale solid-state fermentation. Ergosterol can be a good indicator for phytase generation or phytic acid degradation in solid-state fermentation of soyban meal.