米根霉原生质体电融合条件研究

以米根霉突变株mut-A、mut-B为亲本,采用双亲灭活标记筛选融合子,对亲本灭活条件、原生质体电融合条件进行了研究。实验结果表明,0.6mol/L山梨醇溶液为最适的渗透压缓冲液,mut-A、mut-B的灭活条件分别为50℃加热6min及紫外照射180s。原生质体在电场中排队所需的细胞浓度为1×107/mL,交变电场电压为8V;最佳的电融合参数为直流脉冲电压260V,脉冲持续时间40μs,脉冲次数2次;最高融合率可达7.29±0.71%。     

Screening and selection of microfungi for microbial biomass protein production and water reclamation from starch processing wastewater

Thirty strains of microfungi and amylolytic yeasts were screened for production of microbial biomass protein (MBP) and water reclamation from starch processing wastewater (SPW). Three species and six strains of microfungi Aspergillus oryzae, Rhizopus oligosporus and Rhizopus arrhizus showing high enzymatic activities on SWP were selected under non‐aseptic growth conditions. In 20 h submerged cultivation the selected strains had a high capacity to enzymatically hydrolyse more than 93% of the starch and produce 4.3–5.6 g dm⁻³ of dry biomass at a specific biomass growth rate from 0.05 to 0.12 h ⁻². The fungal biomass contained crude protein ranging from 37.5 to 49.8% of dry biomass. The pellet and flocculated biomass products were easily harvested by simple filtration or sedimentation. After these processes, 76–88% of total organic carbon (TOC), 85%–92% of chemical oxygen demand (COD) and 95% suspended solids in SPW were removed, and the treated water was reusable for farm irrigation. Typical pretreatment processes including hydrolysis, sterilisation and nutrient supplementation were unnecessary. © 1999 Society of Chemical Industry     

新型功能性红曲调味品的研究

本研究以红曲霉，米曲霉为菌种，用不同配比的大米，豆粕，麸皮等为原料，分别进行单菌种及混合菌种培养，培养成熟后，并对其进行发酵，结果表明：可用大米，豆粕为原料培养红曲，米豆比例1．5：1，温度30℃，培养时间6d时为最佳。以红曲霉，米曲霉混合菌种培养，原料以米：豆粕：麸皮比例为1：2：1，温度30℃，培养时间3d为最佳。通过对两种发酵比较：混合菌种培养发酵工艺酿制的新型调味品，在感官及理化指标等方面均优于单菌种培养混合发酵工艺所酿制的调味品。℃     

混合发酵法生产脐橙皮膳食纤维的研究

以绿色木霉和米根霉为发酵菌种,制备脐橙皮膳食纤维,以膳食纤维得率为参考指标,通过单因素及正交试验以优化最佳制备条件,结果表明:最佳制备条件为接种比例(绿色木霉∶米根霉)3∶2;发酵温度25℃;发酵pH值为6.5;发酵时间为3d.此时,所得的发酵产物中,SDF、IDF以及TDF得率分别为32.93％、49.87％、82.80％,持水力和溶胀性分别为6.12 g/g、15.29 mL/g.     

转盘反应器固定米根霉的L－乳酸发酵

研究了米根霉的固定化方法，研制了用吸附法固定米根霉的生物转盘反应器，考察了在该反应器中培养基组成及其它操作条件对Ｌ－乳酸发酵的影响。实验结果表明，应用吸附法固定化的米根霉及生物转盘反应器进行Ｌ－乳酸发酵具有发酵速率快，Ｌ－乳酸得率高及既能用于连续发酵又能用于间歇发酵等优点     

Analysis of the catalyic mechanism of a fungal lipase using computer-aided design and structural mutants

Both an active enzyme conformation and stabilization of tetrahedraltransition states are essential for the catalysis of ester bondhydrolysis by lipases. X-ray structural data and results fromsite-directed mutagenesis experiments with proteases have beenused as a basis for predictions of amino acid residues likelyto have key functions in lipases. The gene encoding a lipasefrom Rhizopus oryzae was cloned and expressed in Escherichiacoli. Site-directed mutagenesis of this gene was used to testthe validity of computer-aided predictions of the functionalroles of specific amino acids in this enzyme. Examination ofthe kinetic constants of the Rhizopus oryzae lipase variantsallowed us to identify amino acid residues which are directlyinvolved in the catalytic reaction or which stabilize the activegeometry of the enzyme. The combination of these results withmolecular mechanics simulations, based on a homology-derivedstructural model, provided new information about structure-functionrelationships. The interpretation of the data is consistentwith results obtained with other hydrolases, such as proteases.     

双菌共发酵餐厨垃圾生产燃料乙醇的新方法

试验对分离得到的霉菌进行淀粉酶和纤维素酶活性鉴定,获得了一株同时具有淀粉酶和纤维素酶活性的新霉菌。经形态学及分子生物学方法鉴定,初步认定其为一株未被报道过的米根霉,将其命名为Rhizopusoryzae TZY1。Rhizopus oryzae TZY1与保藏酿酒酵母进行餐厨垃圾共发酵,在没有外加任何酶类的条件下,发酵后大部分的淀粉及纤维素被利用,发酵乙醇产率与糖化发酵结果大致相等。发酵后经检测,淀粉的利用率在88%以上,纤维素的利用率在84%左右,较之同步糖化发酵,该方法可以部分避免由于酶失活而使乙醇产率降低的问题,并且不需外加糖化酶类,节约了成本,具有良好的产业化应用前景。     

响应面法优化根霉菌产麦角固醇的液体发酵工艺

以米根霉(Rhizopus oryzae ZW017)发酵产麦角固醇的产量为响应值,对其液体发酵工艺进行优化。采用HPLC法检测菌株产麦角固醇含量,在单因素筛选试验基础上,以PDB液体发酵培养为基础条件,应用响应面分析法(RSM)对碳源、氮源及发酵时间进行优化。结果表明:以葡萄糖、酵母膏分别为最佳碳、氮源;最佳工艺条件为:PDB基础培养基中添加葡萄糖3g/L、酵母膏5g/L、发酵培养9.64d,麦角固醇平均产量达5761.83μg/100mL,较优化前提高了247.86%,与构建模型理论预测值(5818.39μg/100mL)相吻合,且100mL液体培养基中麦角固醇产量占菌体细胞干质量(0.36g)的1.60%。     

薏米保健面酱的加工技术研究

该文以薏米粉、黑米粉、标准粉及菌种米曲霉为原料生产面酱,利用L(934)正交试验进行工艺优化。依据感官评定结果,确定了薏米保健面酱的最佳配方及工艺参数。结果表明:薏米粉的添加量为标准粉的20%、黑米粉的添加量为标准粉的20%、菌种米曲霉的接种量为5‰,在发酵温度为53℃~55℃的条件下,发酵时间为17d,研制成的薏米保健面酱的品质最佳。     

QU3601米曲霉制曲工艺的探讨

介绍了朝鲜族酱生产菌株QU3601米曲霉的制曲工艺。分析了种曲制备，大豆、面粉预处理，制曲条件等对成曲质量的影响。总结了提高成曲酶活力的方法，如制种曲时加入草木灰，浸泡大豆时加入冰醋酸，防止曲室冷凝水污染，制曲不宜多次翻曲等。