纤维素油脂的统合生物加工过程是将纤维素酶生产、纤维素水解和微生物油脂发酵过程组合,通过一种微生物完成.运用统合生物加工过程生产微生物油脂可以降低生物转化过程的成本.该文对20株纤维素降解菌进行筛选评价,结果发现青霉菌株 P‐2同时具备有效的纤维素降解和油脂积累能力.脂肪酸组分分析表明,菌株 P‐2胞内油脂的脂肪酸组分主要为棕榈酸( C16：0,21.05％)、油酸( C18：1,22.43％)和亚油酸( C18：2,27.78％).菌株P‐2在以纤维素粉为底物的液体发酵和以秸秆、麸皮混合物为底物的固态发酵条件下可达到的最高油脂产量分别为0.65 g/L 和40.13 mg/g(按干物质计).说明青霉 P‐2是一株潜在的低成本纤维素油脂生产菌.进一步分析在发酵试验中的油脂产量和纤维素酶活力发现,菌株 P‐2的纤维素酶分泌能力在其油脂生产过程中具有重要作用.外源纤维素酶添加试验证实,在培养基中外源纤维素酶添加量的提高可以促进 P‐2油脂的生产.添加24 IU /g (按干物质计)纤维素酶可使 P‐2发酵后的最高油脂产量达到0.83 g/L .对固态发酵所得到的滤纸酶活力和油脂产量数据进行相关分析,结果证实滤纸酶活力与油脂产量之间存在极显著的正相关关系( R2＝0.711,P＜0.01).当固态发酵系统中的滤纸酶活力从1.0 IU /g 增加到3.5 IU /g(按干物质计)时,对应的油脂产量从26.24 mg/g上升到40.13 mg/g(按干物质计),产量增长量达到52.93％.以上结果暗示纤维素酶分泌能力不足是制约 P‐2油脂产量的一个重要原因；因此,通过调控菌株 P‐2的纤维素酶分泌能力可能是提高油脂产量的可行性策略之一.%Summary Consolidated bioprocessing (CBP) is a convenient and cost‐efficient strategy to produce single cell oils ( SCOs ) from cellulose‐based substrates . In this study , Penicillium P‐2 having both effective cellulose degradation and lipid accumulation was isolated from 20 cellulolytic fungi . The SCOs of the strain P‐2 were mainly composed of palmitic acid ( C16 :0 , 21 .05% ) , oleic acid ( C18 :1 , 22 .43% ) and linoleic acid ( C18 :2 , 27 .78% ) . Fermentation experiments of the strain P‐2 showed that maximum lipid yields of 0 .65 g/L and 40 .13 mg/g ( per gram dry mass of initial solid substrate) could be obtained by submerged fermentation ( SmF) from cellulose and solid‐state fermentation (SSF) from wheat straw and bran mixture , respectively . The results from the two CBP indicated that the strain P‐2 had a potential to be a promising low‐cost oil producer using cellulose‐based substrates . The further analysis for lipid accumulation and cellulase secretion of the strain P‐2 suggested that the cellulase secretion of the strain P‐2 might play a key role in the lipid production . The submerged fermentation with exogenous cellulase addition by the strain P‐2 demonstrated that the higher exogenous cellulase dosages could lead to higher lipid production and the lipid yield would increase up to 0 .83 g/L with the addition of 24 IU /g cellulase . A highly significant positive correlation between the filter paper activity ( FPA) and the lipid yield in the strain P‐2 was further observed on the data pooled from the SSF parameter treatments ( P < 0 .01) . When the detected FPA in SSF system increased from 1 .0 IU /g to 3 .5 IU /g , the lipid yield was also increased from 26 .24 mg/g to 40 .13 mg/g with the increment of 52 .93% . All these analyses suggest that the weak cellulase secretion of the strain P‐2 is an important cause of the low lipid yield , so the regulation of endogenous cellulase secretion might be a feasible strategy for enhancing lipid production of the strain P‐2 .
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