Distinction between enzymically and chemically catalyzed interesterification

The 1,3-specific lipase-catalyzed interesterified fats were distinguished from chemically catalyzed products by the fatty acids in the 2-position. The fatty acid contents in the 2-position of the 1,3-lipase-catalyzed and the original triglycerides were similar but different from that of chemically interesterified fat. Also, the saturated-to-unsaturated fatty acid ratio in the 2-monoglycerides was lower for the 1,3-specific lipase-catalyzed interesterified fats than for the corresponding chemical products.     

Co-Production of Fungal Biomass Derived Constituents and Ethanol from Citrus Wastes Free Sugars without Auxiliary Nutrients in Airlift Bioreactor

The potential of two zygomycetes fungi, Mucor indicus and Rhizopus oryzae, in assimilating citrus waste free sugars (CWFS) and producing fungal chitosan, oil, and protein as well as ethanol was investigated. Extraction of free sugars from citrus waste can reduce its environmental impact by decreasing the possibility of wild microorganisms growth and formation of bad odors, a typical problem facing the citrus industries. A total sugar concentration of 25.1 g/L was obtained by water extraction of citrus waste at room temperature, used for fungal cultivation in shake flasks and airlift bioreactor with no additional nutrients. In shake flasks cultivations, the fungi were only able to assimilate glucose, while fructose remained almost intact. In contrast, the cultivation of M. indicus and R. oryzae in the four-liter airlift bioreactor resulted in the consumption of almost all sugars and production of 250 and 280 g fungal biomass per kg of consumed sugar, respectively. These biomasses correspondingly contained 40% and 51% protein and 9.8% and 4.4% oil. Furthermore, the fungal cell walls, obtained after removing the alkali soluble fraction of the fungi, contained 0.61 and 0.69 g chitin and chitosan per g of cell wall for M. indicus and R. oryzae, respectively. Moreover, the maximum ethanol yield of 36% and 18% was obtained from M. indicus and R. oryzae, respectively. Furthermore, that M. indicus grew as clump mycelia in the airlift bioreactor, while R. oryzae formed spherical suspended pellets, is a promising feature towards industrialization of the process.     

Enzymatic alcoholysis reaction of soy phospholipids

Lipase-catalyzed alcoholysis of soy phospholipids was investigated to simultaneously make lysophospholipids and fatty acid esters of individual alcohols. Alcoholysis was carried out by stirring a mixture of soy phospholipids and individual alcohols in equimolar proportions with 10% (by weight of reactants) Mucor miehei lipase at 55°C for 24 h. The products were isolated by column chromatography after removal of the lipase. Lysophospholipids (in 69–78% molar yield) were obtained from soy phospholipids, and the yield of esters of various alcohols also conformed nearly with theoretical yields.     

Enzymatic modification of trilinolein: Incorporation of n-3 polyunsaturated fatty acids

Two immobilized lipases, IM60 fromMucor miehei and SP435 fromCandida antarctica, were used as biocatalysts for the modification of trilinolein with n-3 polyunsaturated fatty acids (PUFA), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), by using their ethyl esters as acyl donors (EEPA and EDHA, respectively). Transesterification (ester-ester interchange) reactions were carried out in organic solvent. The products were analyzed according to their equivalent carbon number and polarity by reverse-phase high-performance liquid chromatography, and the fatty acid profiles were determined by gas-liquid chromatography. Modified triacylglycerol products contained 1 or 2 molecules of n-3 PUFA. With EEPA as the acyl donor, the total EPA product yields with IM60 and SP435 as biocatalysts were 79.6 and 81.4%, respectively. However, with EDHA as the acyl donor and IM60 and SP435 as biocatalysts, the total DHA product yields were 70.5 and 79.7%, respectively. Effects of reaction parameters, such as type of solvent, enzyme load, time course, and molar ratio of substrates on the n-3 PUFA incorporation, were followed with SP435 as the biocatalyst. High yields were obtained, even in the absence of organic solvent. These lipids do hold promise for specialty nutrition and other therapeutic uses.     

Enzymatic preparation of ricinoleic acid esters of long-chain monohydric alcohols and properties of the esters

Apart from the conventional chemical esterification process, long-chain alkyl ricinoleates also can be prepared by enzymatic esterification or by enzymatic alcoholysis with high yield and without undesirable side reactions. On sulfonation to the hydroxyl group, the alkyl ricinoleates produce surface-active compounds. The tetradecyl ricinoleate shows the best surface-active behavior and seems to be much better than that of sulfonated castor oil commonly known as “Turkey Red Oil”.     

Microbial conversion of androst‐1,4‐dien‐3,17‐dione by Mucor racemosus to hydroxysteroid‐1,4‐dien‐3‐one derivatives

BACKGROUND: A large number of bacterial, fungal and microalgal species are able to bio‐transform steroid compounds. Among them, fungi from the Mucor genus have been shown to mediate hydroxylation, oxidation, and desaturation by the double bond formation and epoxidation of various steroid substances. Mucor racemocus has not been studied for its ability to modify androst‐1,4‐dien‐3,17‐dione, a pharmaceutically important steroid precursor. RESULTS: The filamentous fungus M. racemosus was applied for bioconversion of androst‐1,4‐dien‐3,17‐dione (ADD, I ) in a 5‐day fermentation. Microbial metabolites were purified chromatographically and identified on the basis of their spectral data as 17β‐hydroxyandrost‐1,4‐dien‐3‐one ( II ), 14α‐hydroxyandrost‐1,4‐dien‐3,17‐dione ( III ), 15α‐hydroxyandrost‐1,4‐dien‐3,17‐dione ( IV ), 15α,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( V ), 14α,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( VI ), and 6β,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( VII ). CONCLUSION: Observed modifications included hydroxylation at C‐6β, C‐14α, C‐15α positions and 17‐carbonyl reduction. The best fermentation conditions for production of hydroxysteroid‐1,4‐dien‐3‐one derivatives were found to be 25 °C at 150 rpm for 5 days with a substrate concentration of 0.5 g L^?1. Copyright © 2009 Society of Chemical Industry     

固体发酵制备毛霉蛋白酶的研究

该文研究了毛霉M2产蛋白酶的若干影响因素，包括培养基的成分以及发酵条件等。结果表明：在麸皮与水的合适比例为1：0.8；在基本培养基上添加一定浓度的碳源、氮源及无机盐有利于蛋白酶的合成；菌体较为合适的产酶条件为温度28℃，pH6．0，发酵时间36h。     

腐乳生产用毛霉高产端肽酶菌株诱变条件及发酵特性的研究

毛霉在腐乳的酿造过程时对腐乳的独特的风味的形成起极其重要的作用,要提高腐乳产品风味,既提高鲜味又降低苦味,从根本上是要解决高蛋白酶系生成及端肽酶产率的问题。本实验通过复合诱变的方法确定一种高产酶系,并端肽酶系含量较高的菌株,通过复合诱变(Co60、紫外)克服单一诱变的缺点,同一诱变因子的重复作用效果不明显,多种诱变因子共同作用效果最好,使菌株产氨基酸的能力提高22%,确定了诱变的辐射剂量在8万伦琴,紫外诱变时间60s为最佳条件。优选出产端肽酶高的菌株,经过诱变,通过新菌种及生产条件的优化,在此基础上又提高30%。确定培养适宜温度为28℃,较佳培养时间48h,最佳起始pH7.2,接菌量10%的培养条件下产蛋白酶活最高,发酵产氨基酸含量也最高,即端肽酶活力最高。由于受腐乳产品自身特点限制,食盐及乙醇的浓度分别设定在6%和4%,为发酵最佳条件。发酵后腐乳产品风味有了明显的改善,鲜味提高、苦味降低。对于生产具有更重要的意义,尤其对提高腐乳这一传统食品的营养效价更具深远意义。     

豆渣菌糠浅盘发酵制备微小毛霉凝乳酶的研究

为考察将豆渣和金针菇菌糠这两种废弃资源应用于微小毛霉凝乳酶固态浅盘发酵的效果,以医用托盘作为发酵容器,以干燥后的豆渣菌糠1∶1(质量比)混合物为培养基,以固液比1∶1(质量比)加水润湿培养基,121℃灭菌冷却后接种微小毛霉进行发酵.发酵72 h时,加水提取酶,将酶液进行浓缩、盐析、透析以及冷冻干燥后获得凝乳酶粉末.结果显示,以豆渣和菌糠混合物为发酵培养基时,其单位发酵面积最大产酶量可达到1 860 SU/cm2,略高于对照麦麸1 618 SU/cm2的发酵水平,这表明豆渣和菌糠混合物能够替代麦麸用于微小毛霉凝乳酶的固体浅盘发酵.此外,酶提取液经初步分离纯化,可获得凝乳活力为7 497 SU/mg、水解酶活为0.22 Ucas/mg、纯度大于50％的凝乳酶粉末制剂.     

Effects of Plant Growth Hormones on Mucor indicus Growth and Chitosan and Ethanol Production

The objective of this study was to investigate the effects of indole-3-acetic acid (IAA) and kinetin (KIN) on Mucor indicus growth, cell wall composition, and ethanol production. A semi-synthetic medium, supplemented with 0–5 mg/L hormones, was used for the cultivations (at 32 °C for 48 h). By addition of 1 mg/L of each hormone, the biomass and ethanol yields were increased and decreased, respectively. At higher levels, however, an inverse trend was observed. The glucosamine fraction of the cell wall, as a representative for chitosan, followed similar but sharper changes, compared to the biomass. The highest level was 221% higher than that obtained without hormones. The sum of glucosamine and N-acetyl glucosamine (chitin and chitosan) was noticeably enhanced in the presence of the hormones. Increase of chitosan was accompanied by a decrease in the phosphate content, with the lowest phosphate (0.01 g/g cell wall) being obtained when the chitosan was at the maximum (0.45 g/g cell wall). In conclusion, IAA and KIN significantly enhanced the M. indicus growth and chitosan production, while at the same time decreasing the ethanol yield to some extent. This study shows that plant growth hormones have a high potential for the improvement of fungal chitosan production by M. indicus.