豆腐酸浆中高产蛋白微生物的氨基酸营养分析

对豆腐酸浆中假丝酵母和白地霉的蛋白质中氨基酸进行了研究，测得其含有18种氨基酸，8种必需氨基酸齐全，还含有组氨酸。根据模式蛋白质，应用模糊识别分析法与化学分析法对假丝酵母和白地霉蛋白质营养价值进行了评价。     

响应面法优化微生物油脂发酵条件

利用响应面分析法对健强地霉G9菌株生产微生物油脂的发酵条件进行优化.通过Plackett-Burman设计法,对影响菌株油脂产量的8个因素进行考察,确定温度、KH2 PO4添加量和花生饼粉添加量为对油脂产量有显著影响的3个重要因素.采用响应面法对3个重要因素的最佳水平进行优化,结果表明菌株最佳产油条件为:温度28℃,KH2PO4添加量16 g/L,花生饼粉添加量16 g/L.在此条件下进行摇瓶培养,健强地霉G9菌株油脂产量达10.73 g/L.采用优化的摇瓶实验条件进行5L罐上发酵培养,菌株油脂产量达28.63 g/L,为摇瓶培养时的2.67倍,说明该优化条件也适用于5L发酵罐生产,且健强地霉G9菌株适合放大生产,具有作为工业微生物生产菌种的潜力.     

壳聚(寡)糖对柑橘酸腐、黑腐病菌的抑制作用及对采后病害的防治

通过体外实验测定不同浓度的壳聚糖和壳寡糖对酸腐和黑腐病菌孢子萌发、芽管长度和菌丝生长的抑制作用;采用刺伤接种方法评价壳聚糖和壳寡糖对柑橘果实两种病害的防治作用。离体实验结果表明,壳聚糖和壳寡糖浓度为10mg/mL时几乎完全抑制两种病原菌的菌丝生长;浓度为0.5mg/mL壳聚糖和壳寡糖能完全抑制柑橘酸腐病菌(Geotrichum candidum)孢子萌发和芽管伸长的效果,而2mg/mL的壳聚糖才能完全抑制柑橘黑腐病菌(Alternaria citri)孢子萌发和芽管伸长,但相同浓度的壳寡糖抑制A.citri的孢子萌发和芽管伸长效果较差。体内实验结果表明,其病害防治效果具有浓度依赖性,高浓度(1%)的壳聚糖和壳寡糖对果实病害的防治效果较低浓度的防治效果好。      

白地霉在清香型基酒生产中的应用

白地霉属半知菌亚门,丝孢纲,丝孢目,丛梗孢科,地霉属,是真菌的一种。在葡萄糖、甘露糖、果糖上能微弱发酵;有氧时能同化甘油、乙醇、山梨醇和甘露醇。目前牛栏山酒厂分离保存白地霉1株,因闻到浓郁的香甜气息,故将其作为重点菌株实验。经过试验应用到酿酒生产中,取得了良好的效果。所产基酒口味纯净,表现出醇甜,绵柔的特点,质量明显提高。     

Application of strains of Geotrichum spp. to decrease higher alcohols and to increase esters

The decrease in the content of higher alcohols and the increase in the ester content in alcoholic drinks are normally achieved by the aging process over years. This study examined the capability of some strains of Geotrichum spp. to complete this process within a few days. Four Geotrichum spp. strains (S12, S13, TM and TF) were separately added to one wine [containing 11.5% (v/v) ethanol] and to three liquor samples [containing 45, 50 and 55% (v/v) ethanol] and incubated at 28 and 15°C for 4 days. Significant increases in the ester content and decreases in the higher alcohols were observed with strains S12 and TM, in all treatments. Strains S13 and TF increased the ester content in the wine, but not in the liquors. Comparatively, most volatile compounds were found in the red wine treated with S12 at 15°C and in the liquor containing 55% (v/v) ethanol treated with TM at 28°C. The conversion from higher alcohols to their corresponding acids and esters was identified using gas chromatography coupled with mass spectrometry during the treatments. By comparing the results when enzyme extracts and whole cells were used, it was found that the decrease in the levels of the higher alcohols might be caused both by cell adsorption and enzymatic reactions, whereas the increase in the esters was caused mainly by enzymatic reactions. Copyright © 2016 The Institute of Brewing & Distilling     

Detection of the sour-rot pathogen Geotrichum candidum in tomato fruit and juice by using a highly specific monoclonal antibody-based ELISA

Geotrichum candidum is a common soil-borne fungus that causes sour-rot of tomatoes, citrus fruits and vegetables, and is a major contaminant on tomato processing equipment. The aim of this work was to produce a monoclonal antibody and diagnostic assay for its detection in tomato fruit and juice. Using hybridoma technology, a cell line (FE10) was generated that produced a monoclonal antibody belonging to the immunoglobulin class M (IgM) that was specific to G. candidum and the closely related teleomorphic species Galactomyces geotrichum and anamorphic species Geotrichum europaeum and Geotrichum pseudocandidum in the G. geotrichum/G. candidum complex. The MAb did not cross-react with a wide range of unrelated fungi, including some likely to be encountered during crop production and processing. The MAb binds to an immunodominant high molecular mass (> 200 kDa) extracellular polysaccharide antigen that is present on the surface of arthroconidia and hyphae of G. candidum. The MAb was used in a highly specific enzyme-linked immunosorbent assay (ELISA) to accurately detect the fungus in infected tomato fruit and juice. Specificity of the ELISA was confirmed by sequencing of the internally transcribed spacer (ITS) 1-5.8S-ITS2 rRNA-encoding regions of fungi isolated from naturally-infected tomatoes.     

香叶醇对柑橘酸腐病菌的抑菌机制

为研究香叶醇对柑橘酸腐病菌（Geotrichum citri-aurantii）的抑菌机制,用不同质量浓度的香叶醇处理柑橘酸腐病菌,通过生理生化分析及微观结构观察研究其对酸腐病菌孢子和菌丝体的影响。结果表明,香叶醇对柑橘酸腐病菌的最小抑菌质量浓度（minimal inhibitory concentration,MIC）和最小杀菌质量浓度（minimal fungicidal concentration,MFC）均为0.500 g/L;MIC香叶醇处理酸腐病菌12 h后其孢子萌发率仅为（3.28±1.28）%,显著低于对照组的（92.17±1.88）%(P<0.05)。透射电子显微镜观察发现,香叶醇处理破坏了酸腐病菌细胞的完整性,细胞壁与细胞膜发生质壁分离,细胞器无法分辨,呈现空泡化。细胞通透性发生改变,碱性磷酸酶和核酸发生外泄,相对电导率升高,膜脂质过氧化反应增强,活性氧积累。综上所述,香叶醇通过抑制柑橘酸腐病菌孢子萌发和菌丝生长、破坏细胞结构、促进脂质过氧化和活性氧积累从而影响其正常生理功能,本实验可为有效防治柑橘酸腐病提供新思路。     

Differences in hydrolytic abilities of two crude lipases from Geotrichum candidum 4013

The fungus Geotrichum candidum 4013 produces two types of lipases (extracellular and cell‐bound). Both enzymes were tested for their hydrolytic ability to p‐nitrophenyl esters and compounds having a structure similar to the original substrate (triacylglycerols). Higher lipolytic activity of extracellular lipase was observed when triacylglycerols of medium‐ (C12) and long‐ (C18) chain fatty acids were used as substrates. Cell‐bound lipase preferentially hydrolysed trimyristate (C14). The differences in the abilities of these two enzymes to hydrolyse p‐nitrophenyl esters were observed as well. The order of extracellular lipase hydrolysis relation velocity was as follows: p‐nitrophenyl decanoate > p‐nitrophenyl caprylate > p‐nitrophenyl laurate > p‐nitrophenyl palmitate > p‐nitrophenyl stearate. The cell‐bound lipase indicates preference for p‐nitrophenyl palmitate. The most striking differences in the ratios between the activity of both lipases (extracellular : cell‐bound) towards different fatty acid methyl esters were 2.2 towards methyl hexanoate and 0.46 towards methyl stearate (C18). The Michaelis constant (K_m) and maximum reaction rate (V_max) for p‐nitrophenyl palmitate hydrolysis of cell‐bound lipase were significantly higher (K_m 2.462 mM and V_max 0.210 U/g/min) than those of extracellular lipase (K_m 0.406 mM and V_max 0.006 U/g/min). Copyright © 2010 John Wiley & Sons, Ltd.     

Analysis of batch submerged cultivations of Geotrichum candidum growing in lactate with either glutamate or lysine

Amino acid and lactate assimilation by Geotrichum candidum were examined in submerged culture. G candidum growth on lysine and lactate clearly showed that lactate can be assimilated as a carbon source, in addition to an energy source. Lysine was chosen since G candidum did not grow on lysine as the sole carbon and nitrogen source. On the contrary, when a convenient carbon source amino acid (glutamate) was used, lactate appeared to have no effect on G candidum growth; it was only assimilated at a low rate during the stationary state for energy supply, in agreement with previous observations recorded during growth on peptones. The assimilation of glutamate, the more convenient substrate for G candidum growth, required less energy than lysine assimilation, indicated by the lower level of CO₂ released. Copyright © 2004 Society of Chemical Industry     

Positional and fatty acid specificities of Geottichum candidum Upases

Geotrichum candidum ATCC34614 produces a major (I) and threeminor (II, HI and TV) forms of lipase with similar molecularmasses, but different positional and fatty acid specificities.The major and one of the minor (II) forms were confirmed tocleave both the inside and outside ester bonds of triolein indiscriminately.The non-positional specificity was also retained on l,3-dipalmitoyl-2-oleoyl-glycerol(POP) hydrolysis. In contrast, the remaining two forms (IIIand IV) showed unusual positional specificity; they cleavedthe inside (2-position) ester bond of triolein at nearly twicethe rate of cleavage at the l(3)-position. The preference forthe inside ester bond was increased upon POP hydrolysis.