高产脂肪酶棘孢曲霉筛选、发酵条件优化及其脂肪酶酶学性质OA

A dominant strain with high lipase production capacity was isolated from freeze-dried powder of Aspergillus aculeatus BNCC 19623 via the olive oil plate screening method,whose molecular identification was completed by 18S rDNA sequencing,sequence homology alignment and phylogenetic tree analysis;on this basis,fermentation conditions for lipase biosynthesis of the strain were optimized,and the enzymatic characteristics of its extracellular lipase were systematically explored.The results showed that the screened high lipase-producing strain was identified as A.aculeatus.The optimal fermentation parameters for lipase synthesis were determined as follows:fermentation duration 40 h,fermentation temperature 28℃,olive oil supplementation 5%,inoculation volume 4%,and initial pH 6.5.Under these conditions,the lipase activity reached 162.5 U/mL,which was increased by 46.4%compared with the pre-optimization level of 111.0 U/mL.The optimal ammonium sulfate saturation for lipase salting-out was 70%,and the enzyme exhibited a molecular weight of approximately 32.5 kDa,with its optimal catalytic conditions recorded at 30℃ and pH 8.5–9.0;its activity barely declined after 3 h of water bath incubation at 30℃,whereas roughly 30%activity was lost following 3 h incubation at 40℃,and metal ions(10 mmol/L Ca2+,Mg2+and Zn2+)exerted significant stimulatory effects on lipase activity.The findings of this study provided theoretical references for fermentative production and application of lipase from A.aculeatus.