基于复合菌的玉米芯发酵工艺构建与优化OA

[Objective]High-lignin straw exhibits low feed utilization efficiency due to its high content of acid detergent lignin(ADL).We developed a composite fermentation process using white-rot fungus,Bacillus subtilis,and Pichia pastoris,and evaluated its synergistic degradation effect in corncob.[Method]We constructed a three-strain composite fermentation system consisting of white-rot fungus BF-1(isolated from Lentinula edodes)as the core functional strain,together with Bacillus subtilis and Pichia pastoris at a cell mass ratio of 1:1:1.Corncob served as the fermentation substrate,and single-strain fermentation of BF-1 was used as the control.The degradation efficiency of ADL was compared using single-factor experiments(temperature:28–32℃,moisture content:40％–50％,inoculum size:1％–5％).Response surface methodology was then employed to optimize the fermentation conditions for the three-strain system.Morphological changes in corncobs were examined by scanning electron microscopy(SEM).Crude protein(CP),neutral detergent fiber(NDF),and acid detergent fiber(ADF)were measured to evaluate the relative feed value(RFV)and relative feed quality(RFQ).[Result]Single-factor experiments showed that both fermentation systems achieved optimal ADL degradation at 30℃,45％moisture content,and 3％inoculum size.Under these conditions,the ADL degradation rate of single-strain fermentation was 42.29％,while that of the three-strain fermentation was 58.83％.The degradation efficiency of the three-strain system was significantly higher than that of the single-strain system(P<0.01).Response surface methodology identified the optimal conditions for three-strain fermentation as 29.8℃,45.2％moisture,and 3.1％inoculum,achieving an ADL degradation rate of 63.42％.During fermentation,the activities of laccase(Lac),manganese peroxidase(MnP),and lignin peroxidase(LiP)increased continuously over time.Scanning electron microscopy revealed that after three-strain fermentation,the surface structure of the corncob was more significantly disrupted,exhibiting a loose and porous morphology.After 21 days of fermentation,the CP content in the three-strain system increased by 1.43％(P<0.01),while NDF and ADF contents decreased significantly(P<0.01),with degradation rates of 22.12％and 33.97％,respectively.RFQ and RFV increased by 82.80％and 17.21％,respectively.[Conclusion]The three-strain synergistic fermentation effectively degraded corncob lignin,achieving an ADL degradation rate of 63.42％,a 1.43％increase in CP content,and significant fiber degradation.RFQ was increased by 82.80％,and RFV was substantially enhanced.These findings provide a technical support for the utilization of corncobs as animal feed.