生物可降解塑料的发酵生产研究进展*

近十几年来,随着化学合成塑料造成环境污染的日趋严重,微生物合成生物可降解塑料的研究受到人们的广泛重视.聚羟基烷酸(polyhydroxyalkanoates,PHA)具有与化学合成塑料相似的性质,能拉丝、压模、注塑等,而且具有合成塑料所没有的特殊性能,如利用其生物相容性可作为外科手术缝线、人造血管和骨骼代用品,术后无需取出.因而在工业、农业、医药和环保等行业都具有广阔的应用前景.     

氯代苯胺类化合物微生物降解的研究进展*

对氯代苯胺类化合物(Chlovoanilines,CAS)好氧微生物降解的研究现状进行了系统的综述,内容包括具有降解氯代苯胺类化合物能力的微生物、氯代苯胺类化合物的代谢途径及相关代谢酶的分析、降解质粒和关键代谢酶的基因克隆和表达,并提出了氯代苯胺类化合物好氧微生物降解研究中存在的问题和尚需进一步研究的方面。     

石油烃类化合物降解菌的研究概况*

综述了国内外对石油烃类化合物的微生物降解的研究情况 ,分别就石油烃类化合物各组分微生物降解率、不同组分的微生物代谢途径、降解菌种类、降解性质粒、工程菌构建以及生物修复方法进行了介绍 ,以期全面反映此领域的研究成果 ,为研究工作者提供一定参考依据。     

生物絮凝剂的最新研究进展及其应用*

从絮凝剂的来源和分子组成两方面对生物絮凝剂进行了系统分类,综述了生物絮凝剂产生菌的筛选模型以及生物絮凝剂在水处理和发酵工业中的应用,详细阐述了目前国内外提出的几种不同的生物絮凝剂絮凝机理,进而在此基础上剖析了目前生物絮凝剂研究工作中仍然存在的问题,并提出生物絮凝剂今后的主要研究方向。     

生物滴滤池处理甲苯废气的研究*

以陶粒和活性炭为填料的生物滴滤池系统,对人工合成的甲苯废气进行了净化处理试验,4个多月的运行结果表明:(1)添加活性炭能提高填料柱的处理性能,陶粒和活性炭组成的复合填料能有效地处理含有甲苯的废气,当进气浓度为2·35g/m³时,去除率可达95%以上,填料柱对甲苯的去除能力为130g/m³·h;(2)在低浓度下,生物滴滤池的处理性能受传质过程控制;(3)填料柱出气通过循环液曝气处理后,废气中甲苯浓度进一步降低。     

黄原胶降解菌的筛选及其降解酶性质的研究*

从野外采集并筛选到一株能降解黄原胶的菌株,并对菌种进行了对照鉴定。此外,对菌株的发酵参数、黄原胶降解酶的性质(最适反应温度、pH值,金属离子的影响、底物专一性、动力学研究等)作了初步的研究。结果显示,该酶的最适催化反应温度和pH分别为30℃～40℃和5.0～7.0;能够专一性降解黄原胶;测试大多数金属离子对酶活力没有明显影响,但Ca²⁺能很大程度地缓解EDTA对酶活的抑制作用。     

细菌产木聚糖酶发酵条件的研究*

研究了碳源、氮源以及其他因子对木聚糖酶高产菌ＷＬＵＮ０２４（Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ．）产酶的影响,结果表明在麸皮６ｇ／Ｌ、（ＮＨ４）２ＳＯ４ ０．８ｇ／Ｌ、Ｋ２ＨＰＯ４ ０．４ｇ／Ｌ、接种量５％－１０％的条件下,３７℃培养３６ｈ,其木聚糖酶活力可达６００ＩＵ／ｍＬ。同时研究了在较优条件下该菌的摇瓶产酶曲线。     

微生物降解菲的机理研究进展*

针对微生物降解菲的机理研究进展,论述了细菌、真菌在好氧、厌氧条件下代谢菲的产物以及推测的降解途径;在此基础上概括了催化反应的酶系以及编码酶系的基因簇。简要介绍了基因探针的应用,并结合本实验室的初步研究,指出了该领域有待深入探讨的问题。     

烃的选择性跨膜传输*

研究了烃的跨膜传输过程以及该过程的选择性对细菌降解偏好性的影响。以乳化烷烃实施跨膜传输试验,发现在18h内细胞中的烃含量持续增加。对于各单组分烃,跨膜传输效率没有很大差异;但是,在混合烃的竞争性传输试验中,膜表现出显著的选择性。以分离度衡量膜对4种链长不等烷烃的选择性,发现十六烷,十七烷,二十烷和二十一烷的分离系数分别为1.468,1.121,0.886和0.466,该选择性次序与菌株1.766对混合烃的降解次序相符,说明烃的跨膜传输是决定菌株底物偏好性的重要因素。     

新型生物杀虫剂——刺糖菌素*

刺糖菌素是由土壤放线菌多刺糖多孢菌 (Saccharopolysporaspinosa)产生的次级代谢产物 ,是一种具有触杀及摄食毒性的广谱杀虫剂。对鳞翅目害虫而言 ,刺糖菌素是目前已发现的杀虫剂中选择性最高的化合物之一。文中就刺糖菌素的结构、生物合成、性质以及生产方法进行了综述。     

玉米雄穗性状遗传结构与形成分子机制*

玉米为雌雄同株异花植物,其雄穗着生于植株顶部,雌穗腋生。雄穗一方面需产生足量花粉以保证雌穗授粉结实,另一方面由于对下部叶片的遮蔽作用和自身营养需求,其生长发育会同时影响叶片光合作用效率和能量分配,因此优化雄穗结构是提高玉米产量的重要措施之一。玉米雄穗性状包括雄穗分枝数、雄穗分枝长度、雄穗主轴长度、雄穗分枝总长度、雄穗分枝角度等,均为多基因控制的数量性状。自20世纪90年代,研究者开始利用数量性状位点(quantitative trait locus,QTL)定位方法解析玉米雄穗性状遗传结构;随着玉米自交系B73等参考基因组释放,以及DNA微阵列、基因组重测序等高通量基因分型技术的日益成熟,全基因组关联分析(genome-wide association study, GWAS)成为数量性状遗传研究的主流方法,目前已鉴定出大量玉米雄穗性状遗传位点。通过总结雄穗性状遗传定位研究结果,构建一致性图谱并挖掘定位热点区间,有助于进一步了解雄穗性状遗传结构特征及指导雄穗性状候选基因克隆。此外,通过对调控雄穗发育的已知基因进行功能分类,可为解析玉米雄穗发育的遗传网络和调控通路提供理论支撑。     

Synergistic effect enhances 2-phenylethyl acetate production in the mixed fermentation of Hanseniaspora vineae and Saccharomyces cerevisiae

2-Phenylethyl acetate (2-PEA) is a desired aroma compound in wine due to its honey- and flowery-like characteristics. The effects of adding l-phenylalanine (Phe) during 2-PEA production were investigated in the co-fermentation of Hanseniaspora vineae (HV6) and Saccharomyces cerevisiae BDX. BDX and HV6 strains overproduced 2-phenylethyl alcohol (2-PE) and 2-PEA, respectively. The co-fermentation of BDX and HV6 achieved a 14.9 fold increase in 2-PEA odour activity value (OAV) but a 42.0 % reduction of 2-PE OAV compared to BDX fermentation; the 2-PEA concentration was significantly higher than the sum of BDX and HV6 pure fermentations. This suggests that BDX and HV6 have synergistic effects on 2-PEA formation in mixed culture. Adding 151.6 mg/L Phe enhanced the OAV of 2-PEA by 52.8 % compared to the control. The combination of Phe addition with the co-fermentation of S. cerevisiae and H. vineae is a potential way to increase 2-PEA production and improve wine aromatic quality.     

葡萄酒生境对乳酸菌代谢的影响

在葡萄酒酿造中,为了提高其稳定性及质量,经常利用乳酸菌进行苹果酸.乳酸发酵.苹果酸一乳酸发酵一般自发进行,也可以接种乳酸菌.本文从酿酒酵母与乳酸菌的交互作用及酚类物质和酿酒工艺对乳酸菌的作用等方面进行了综述,讨论了葡萄酒生态环境对乳酸菌代谢的影响,为苹果酸一乳酸发酵的有效控制提供一些参考.     

Loss of testate amoeba functional diversity with increasing frost intensity across a continental gradient reduces microbial activity in peatlands

Soil microbial communities significantly contribute to global fluxes of nutrients and carbon. Their response to climate change, including winter warming, is expected to modify these processes through direct effects on microbial functions due to osmotic stress, and changing temperature regimes. Using four European peatlands reflecting different frequencies of frost events, we show that peatland testate amoeba communities diverge among sites with different winter climates, and that this is reflected through contrasting functions. We found that exposure to harder soil frost promoted species β-diversity (species turnover) thus shifting the community composition of testate amoebae. In particular, we found that harder soil frost, and lower water-soluble phenolic compounds, induced functional turnover through the decrease of large species (−68%, >80 μm) and the increase of small-bodied mixotrophic species (i.e. Archerella flavum; +79%). These results suggest that increased exposure to soil frost could be highly limiting for large species while smaller species are more resistant. Furthermore, we found that β-glucosidase enzymatic activity, in addition to soil temperature, strongly depended of the functional diversity of testate amoebae (R² = 0.95, ANOVA). Changing winter conditions can therefore strongly impact peatland decomposition process, though it remains unclear if these changes are carried-over to the growing season.     

Advanced assessments on innovative methods to improve the bioaccessibility of polyphenols in wheat

Polyphenolic compounds (PCs) are a group of natural antioxidants found in plants. Because most of the PCs exist in bound form in wheat, the efficiency of the solvent extraction method is very low. In general, there are three types of methods used to extract the bound PCs or convert them to free ones and as a result, increase the bioaccessibility of these non-extractable compounds. Although chemical extraction is the most common method used in this way, the enzymatic treatment also accomplishes with less efficiency to break down the linkages between cell wall components and PCs. In recent years, the use of solid state fermentation have been growing up and several microorganisms have been used to produce hydrolyzing enzymes and convert bound PCs to extractable ones. By using this method, the biological effects of the sample originated from the antioxidant property of PCs can be increased in fermented wheat cultivars. This paper provides an overview of different modifications and treatments emphasizing the effect of solid state fermentation as an alternative method for increasing the content of free PCs in wheat.     

生物法处理木质素的研究进展

对生物法处理木质素进行了简要概述,包括微生物降解、生物法酸析提取木质素以及生物法纯化木质素的效果及其研究进展.生物法处理木质素对资源的合理利用、经济的发展以及环境保护具有重要的意义.     

酚顿试剂对竹林土壤中酚类化合物的降解作用

酚类化合物是农业和生态系统中主要的化感物质之一,大量积累在土壤中,抑制作物和林下植物生长,导致农作物减产、连作障碍和自然生态环境破坏。用过氧化氢(H2O2)与硫酸亚铁(Fe2 )所组成的酚顿试剂研究了化学氧化法对化感物质(对香豆酸、对羟基苯甲酸和胡桃醌)、竹林土壤提取物及竹林土壤中对香豆酸的降解作用。过氧化氢与硫酸亚铁的摩尔比为15:1的酚顿试剂,过氧化氢与酚类物质浓度比为8:1时,对酚类物质的降解效率最高。以8×10-3mol/L(0.028%)的H2O2,5.4×10-4mol/L(0.075%)的FeSO4和10-3mol/L的酚类物质组成的反应体系中,反应10min和30min后,对香豆酸的降解率分别为55%和74%;对羟基苯甲酸的降解率在10min时达90%以上;而胡桃醌在10min时已经完全被降解。酚顿试剂处理土壤酚类提取物时,可使其中主要的化感物质对香豆酸降解75%。用含0.1%和1%H2O2的酚顿试剂处理竹(Bambusa chungii)林土壤,土壤对香豆酸的降解率分别为32%和37%。竹林土壤中存在过氧化氢酶和过氧化物酶活性,但没有检测到超氧化物歧化酶活性。土壤中的过氧化氢酶和过氧化物酶可能迅速分解外加的过氧化氢,一方面缩短过氧化氢处理的作用时间和降低降解效率,另一方面可分解过剩的过氧化氢。这说明酚顿试剂是降解土壤和培养液中有害化感物质的有效化学氧化剂。     

Phytochemical analysis of the labdanum-poor Cistus creticus subsp. eriocephalus (Viv.) Greuter et Burdet growing in central Italy

Phenolic constituents and essential oil from the aerial parts of Cistus creticus subsp. eriocephalus (Viv.) Greuter et Burdet growing in central Italy were analysed by HPLC-MSⁿ and GC–MS, respectively. Furthermore, six constituents were isolated by semipreparative HPLC from the methanol extract and their structures were determined on the basis of 1D and 2D NMR measurements as well as MS spectra. Isolated compounds were one new natural product, i.e. the shikimic acid ester 3,5-diihydroxy-4-(O-β-d-glucopyranosyl)-cyclohex-1-en-1-(O-β-d-glucopyranosyl)-ester (27), and six flavonoid glycosides, namely quercetin-3-O-β-D glucopyranoside (16), quercetin-3-O-rhamnoside (17), tricetin-4′-O-β-D glucopyranoside (24), tricetin-4′-O-β-D rutinoside (21), 3′-methoxy-quercetin-3-O-(3-β-Dglucopyranosyl-2-rhamnopyranosil-4-glucopyranosyl-2-rhamnopyranosil)-glucoside (25) and 3′,4′dimethoxyquercetin-3-O-rhamnopyranoside (26). GC–MS analysis of the essential oil highlighted the occurrence of aliphatic compounds, mainly fatty acids, whereas labdane-type compounds were very scant. Our results showed that C. creticus subsp. eriocephalus has a different chemical profile with respect to the other subspecies due to the lack of labdane derivatives. On the other hand, this subspecies contains several phenolic constituents like ellagitannins, gallotannins and flavonoids, some of which can be of chemotaxonomic value.     

Fractionation and Identification of Volatile Acids and Phenols in the Steam Distillate of Rice Bran

Fractionation of the volatile concentrate obtained from steam-distillate of rice bran and organoleptic tests of each fraction were carried out. The neutral fraction gave a much higher yield than others and was assumed to be indispensable for the reproduction of rice bran odor. The acidic fraction methylated with diazomethane and the phenolic fraction were analyzed by glass capillary gas chromatography to identify 17 carboxylic acids and 7 phenols. 4-Vinylguaiacol and 4-vinylphenol identified in the steam volatile concentrate were considered to be produced from ferulic and p-coumaric acids during steam-distillation. 4-Vinylphenol was the main component in the steam volatile concentrate of rice bran, having a characteristic unpleasant odor.     

葡萄酒发酵过程中酵母菌之间相互抑制作用的研究

目的确定葡萄酒发酵过程中不同酵母间相互抑制作用产生的原因。方法采用透析袋发酵法通过单因素实验、上清液抑菌实验和双向电泳等方法,确立溶氧、酒精度、pH、氮源、生存空间以及分泌蛋白等因素对非酿酒酵母衰亡的诱导作用。结果溶氧、酒精、pH、氮源及生存空间的竞争并不是非酿酒酵母提前衰亡的主要原因,酿酒酵母菌产生的代谢产物对非酿酒酵母的提前衰亡具有很强的诱导作用。结论酿酒酵母分泌的分子量小于10kDa的代谢产物和一些分子量超过10 kDa的蛋白类物质均对克鲁维酵母等非酿酒酵母的衰亡具有诱导作用。