草酸青霉线性五肽生物合成的比较转录组分析

草酸青霉(Penicillium oxalicum)是一种重要的植物生防菌,从三峡河岸带分布的草酸青霉中,分离到一种线性五肽,该物质对柑橘致腐菌指状青霉(P. digitatum)具有极强的抑制作用。为了分析该五肽的生物合成机制,本研究采用BGISEQ-500平台,测定了3株不同五肽含量的草酸青霉(114-2,SG-4,SJ-3)cDNA文库,并使用参考基因组对序列进行了比较。高通量测序结果表明,3株草酸青霉平均产出了6.55 GB的序列数据,与有参转录组的平均比对率达到91.65%。差异表达基因比较分析表明,相较于不产五肽的114-2,在生产五肽的SG-4和SJ-3中,共有1 648个基因上调表达,1 251个基因下调表达。AntiSMASH分析表明,在草酸青霉基因组中可能存在33个非核糖体肽合成酶(NRPS),其中15个NRPS的表达与五肽物质的变化趋势一致。进一步的RT-PCR表达分析表明,基因簇PDE_01071可能是负责五肽合成的基因簇。     

Biotransformation of imperatorin by Penicillium janthinellum. Anti-osteoporosis activities of its metabolites

Imperatorin (IMP) is a major constituent of many herbal medicines and possesses anti-osteoporosis activity. The present research work aimed to study the biotransformation processes of IMP and evaluated the anti-osteoporosis activity of the transformed metabolites. Among 18 strains of filamentous fungi screened, Penicillium janthinellum AS 3.510 exhibited good capability to metabolise IMP to the new derivatives. Ten transformed products were isolated and purified, and their structures were identified accurately based on spectroscopic data. Eight metabolites (2–8 and 10) were novel and previously unreported. The major biotransformation reactions involved hydroxylation of the prenyloxy side-chain and the lactone ring-opening reaction of furocoumarin skeleton. In addition, anti-osteoporosis activities of all products (1–10) were evaluated using MC3T3-E1 cells. The results showed that products 5 and 8 had the best bioactivities in increasing MC3T3-E1 cell growth. These products could be used in future therapeutic regimens for treating osteoporosis.     

Inhibition of Penicillium expansum by an oxidative treatment

Several oxidizing compounds such as sodium hypochlorite (NaClO) and hydrogen peroxide (H₂O₂) are used to control postharvest decay in fresh fruit due to their antimicrobial effects. Here, we applied these compounds in vitro, in the presence of CuSO₄, against Penicillium expansum, causal agent of apple blue mold. MICs were 50 mg L⁻¹ and 400 mmol L⁻¹ for NaClO and H₂O₂, respectively, when these compounds were individually applied to conidia suspensions during 2 min. A combined oxidative treatment (OT) consisting on an incubation with 1 mg L⁻¹ NaClO and 200 mmol L⁻¹ H₂O₂, in the presence of 6 mmol L⁻¹ CuSO₄, inhibited growth, conidial germination and fungal infectivity on apple. The fractional inhibitory concentration index for the interaction between NaClO and H₂O₂ in the OT was 0.52 indicating a synergistic effect of the oxidizing compounds. These results suggest that the OT could be an interesting alternative for apple diseases postharvest control.     

圆弧青霉产碱性脂肪酶的中试发酵

圆弧青霉PG3 7是碱性脂肪酶的高产菌 ,在摇瓶和 2 5L发酵罐小试的基础上进行 3M3发酵罐中试 .适合的发酵条件为 :发酵培养基 (% )　豆饼粉 3 .0 ,玉米浆 3 .0 ,磷酸氢二钾 1 .0 ,硫酸镁0 .1 ,大豆磷脂 0 .5,柠檬酸钠 0 .0 5,花生油 0 .2 ;发酵起始 pH值为 8.0 ,发酵温度 2 9± 1℃ ,接种量8%～ 1 0 % ,通风量 0 .8L/ (L·min) ,搅拌转速 2 4 0r/min ,发酵周期 72h ,期间于 3 0、4 2、54h分别各流加 0 .4 %花生油 .在上述条件下 ,圆弧青霉PG3 7发酵酶活达 2 0 0 0 μmol/ (min·mL)     

一株青霉发酵产生木素过氧化物酶的工艺条件

研究了一株青霉菌P6 (Penicillium sp. P6)液体发酵产生木素过氧化物酶的工艺条件,考察了青霉菌P6在天然培养基稻米糠、玉米糠、麦糠和合成培养基GMY中的产酶情况,结果表明,麦糠是较理想的底物. 通过单因素方法研究了添加苯甲醇和MnSO4对酶活的影响;采用正交实验对MnSO4添加量、麦糠含量和培养基pH进行了研究,在实验范围内最佳酶活达到了2.69 U/mL. 进一步通过单双因素回归实验研究了麦糠和MnSO4的最佳含量,得到了最佳培养条件为孢子接种量1.1×106 mL-1,培养时间8 d,500 mL三角瓶装液量150 mL. 最佳培养基组成为麦糠50 g/L,初始pH 4.8, MnSO4 5.66 mmol/L.     

Production of 6,8-Dihydroxy Fatty Acids by Recombinant Escherichia coli Expressing T879A Variant 6,8-Linoleate Diol Synthase from Penicillium oxalicum

Recombinant Escherichia coli expressing T879A variant 6,8-linoleate diol synthase (LDS) from Penicillium oxalicum showed 2.1-fold higher activity than recombinant E. coli expressing wild-type 6,8-LDS for the production of 6,8-dihydroxy fatty acids (DiHFA) from linoleic acid. The optimal conditions for the production of 6,8-DiHFA by recombinant E. coli expressing T879A variant 6,8-LDS were pH 6.5, 35°C, 50 g L⁻¹ cells, 10 g L⁻¹ (35.7 mM) substrate, and 5% (v/v) dimethyl sulfoxide. Under these optimized conditions, 6.6 g L⁻¹ (22.1 mM) 6,8-dihydroxy-9,12(Z,Z)-octadecadienoic acid (DiHODE) and 7.1 g L⁻¹ (22.6 mM) 6,8-dihydroxy-9(Z)-octadecenoic acid (DiHOME) were produced from linoleic acid and oleic acid in 40 min, respectively. The volumetric productivities of 6,8-DiHODE and 6,8-DiHOME under these conditions were 9.9 and 10.7 mg L⁻¹ h⁻¹, respectively. The volumetric productivities of 6,8-DiHODE and 6,8-DiHOME were the highest values among those of all reported regiospecific DiHODE and DiHOME, respectively. To the best of our knowledge, this is the first quantitative biotechnological production of 6,8-DiHFA.     

Production of MAG of CLA by esterification with dehydration at ordinary temperature using <Emphasis Type="Italic">Penicillium camembertii</Emphasis> lipase

Production of MAG with CLA using Penicillium camembertii mono- and diacylglycerol lipase (referred to as lipase) was attempted for the purpose of expanding the application of CLA. The commercial product of CLA (referred to as FFA-CLA) is a FFA mixture containing almost equal amounts of 9cis,11trans (9c,11t)-CLA and 10t,12c-CLA. Esterification of FFA-CLA with glycerol without dehydration achieved 84% esterification but produced almost equal amounts of MAG and DAG. Esterification with dehydration not only achieved a high degree of esterification but also suppressed the formation of DAG. When a mixture of FFA-CLA/glycerol (1∶2, mol/mol), 1% water, and 200 units/g-mixture of P. camembertii lipase was agitated at 30°C for 72 h with dehydration at 5 mm Hg, the degree of esterification reached 95% and the contents of MAG and DAG were 90 and 6 wt%, respectively. This reaction system may be applied to the industrial production of MAG with unstable CLA.     

梅林青霉Z18纤维素酶降解纤维素的研究

为增加纤维素的酶解反应速率,通过降解羧甲基纤维素钠、微晶纤维素、纤维素粉Sigmacell type50,研究梅林青霉(Penicillium Melinii Thom)Z18菌株纤维素酶的特性和作用条件.结果表明:纤维素底物浓度影响酶降解效率,纤维素浓度高于5%时,产生明显底物抑制,50~70℃和pH5.5是纤维素酶解最佳温度和酸碱度,酶解时间的延长有利于降解,但反应超过2 h,还原糖增加缓慢,K+和Mn2+能够增加纤维素酶降解羧甲基纤维素钠和纤维素粉Sigmacell type50效率,Fe2+和Cu2+对于所有纤维素酶解表现抑制,较低结晶度的羧甲基纤维素钠降解速率高于较高结晶度的纤维素粉,纤维素酶水解作用条件的优化和纤维素结晶度的降低能够提高纤维素酶的水解反应速率.     

Phototoxicity ofCitrus jambhiri to fungi under enhanced UV-B radiation: Role of furanocoumarins

Extracts ofCitrus jambhiri foliage exposed to and shielded from UV-B radiation were assayed for phytochemical changes and phototoxicity against four fungal pathogens, two of which (Fusarium solani andF. oxysporum) are causative agents of root rots and two of which (Penicillium italicum andP. digitatum) are associated with fruit rots. Conidial pigment mutants of these four fungal species were assayed to determine whether pigments play a role in protecting fungi against plant photosensitizers. Exposure to 10.2 kJ/ day UV-B radiation for 95 days significantly reduced phototoxicity of leaf extracts to fungi. Although furanocoumarin levels were reduced by UV-B, analysis of covariance revealed that variation in phototoxicity of the extracts cannot be attributed entirely to variation in furanocoumarin content; thus, the possibility exists that nonfuranocoumarin phototoxic constituents, as yet unidentified, respond to UV-B exposure and contribute to overall phototoxic defense ofC. jambhiri against pathogens. Root rot fungi were substantially more sensitive to furanocoumarin phototoxicity than were fruit rot fungi, a pattern consistent with the amount of light exposure normally experienced by these fungi when associated with phototoxic plants. Although pigmented strains of all four species displayed greater resistance to phototoxicity of pure furanocoumarins, no strain differences were detected in assays of foliar extracts; this finding also suggests that nonfuranocoumarin constituents may be involved in the phototoxic defense ofC. jambhiri against pathogens.Deceased.     

青霉T24-2降解甘蔗渣及发酵产氢的研究

通过单因素试验及正交试验对青霉（Penicilliumsp.）T24-2产纤维素酶及酶解甘蔗渣的条件进行优化,并分析了产酸克雷伯氏菌（Klebsiella oxytoca）HP1利用甘蔗渣糖化液产氢的特性。单因素试验结果表明,蔗渣/麸皮质量比、曲酶/蔗渣质量比、固（曲酶＋蔗渣）/液（水）质量比、糖化时间是影响产纤维素酶和蔗渣糖化率的主要因素。经正交试验并考虑大规模应用时的成本,确定青霉T24-2固态发酵产纤维素酶的最佳蔗渣/麸皮质量比为4∶6。利用曲酶对甘蔗渣进行糖化的最佳条件为：曲酶/蔗渣质量比为1∶3,固（曲酶＋蔗渣）/液（水）质量比为1∶3,糖化时间为20h,在此条件下甘蔗渣糖化率可达43.6%。产氢试验表明产酸克雷伯氏菌HP1利用甘蔗渣糖化液,每克甘蔗渣产氢可达41.0mL。研究表明青霉T24-2是一株较好的产纤维素酶菌株,可应用于纤维素生物质的开发与利用。