茯砖茶发花过程中优势菌的研究进展

本文对茯砖茶发花过程中优势菌--冠突散囊菌(Eurotium cristatum)的特征、生长条件、毒性、营养保健作用及发花过程中茯砖茶主要成分变化的研究进展进行了综述.     

茯砖茶冠突散囊菌多样性初步研究

从湖南的不同地区采得较具代表性的茯砖茶样品7种,分离纯化各样品中优势微生物"金花菌"。以广东微生物研究所鉴定确认的冠突散囊菌(Eurotium cristatum)作为标准菌株,描述并比较各菌株平板培养下菌落大小、形状、颜色、质地等特征,以及电镜下有性型与无性型等生理结构的差异,并依据各菌株形态特征上的典型差异对它们予以初步命名。结果表明:七株菌株均属于冠突散囊菌,但在形态和在生理等特征上有四种却表现出较为明显的分化,可能属于冠突散囊菌的变型。本研究为冠突散囊菌多样性的鉴定与不同生理小种的命名提供了基础。     

冠突散囊菌对茶叶品质的影响及其发酵茶的功能活性研究进展

冠突散囊菌（Eurotium Cristatum）是茯砖茶“发花”过程中形成的优势菌种,是目前研究较深入的发酵类真菌。冠突散囊菌发酵茶叶后可改善茶汤滋味与香气,赋予茶叶多种活性生理功能。综述了冠突散囊菌的分离与鉴定、对茶叶品质的影响以及冠突散囊菌发酵茶的功能活性等方面的研究结果,旨在为冠突散囊菌发酵茶新产品的开发与应用提供参考。     

茯砖茶中散囊菌的产毒性研究——Ⅰ.散囊菌培养液的毒性

用卤虫生物测试法对茯砖茶中分离的21株散囊菌进行产毒性筛选。在蔗糖酵母浸汁培养基上培养的散囊菌滤液用卤虫幼虫进行毒性测定,发现47.6%的菌株培养液对卤虫呈现毒性。其中毒性最大的是匍匐散囊菌032号,其培养液对卤虫的 LC_(60)是0.164μ1/m1,它的卤虫毒性单位是6098μ1/m1,并可引起小鼠急性中毒死亡。冠突散囊菌除1株菌外对卤虫幼虫不呈现毒性。文中还对散囊菌的培养性质、产毒特点作了分析和讨论。认为茯砖茶中除冠突散囊菌之外,其它散囊菌不应存正。     

茯砖茶中冠突散囊菌的代谢产物研究Ⅰ冠突散囊菌的液体培养

研究了茯砖茶中冠突散囊菌的液体培养和茶叶提取液培养．旨在研究茯砖茶中冠突散囊菌的代谢产物对茯砖茶品质形成机理及其对茯砖茶功能性成分的影响。     

茯砖茶发花中优势菌的演变规律

采用微生物学的方法,探讨了茯砖茶发花中的优势菌种及其演变规律和生长繁殖的最适环境条件,同时探讨了添加诱发剂(YFJ)对发花的影响。结果表明,湖南茯砖茶中的优势菌为冠突散囊菌(Eurotium Cristatum)。发花初期,相对湿度控制在70%以下,温度在25℃左右,发花中期,在相对湿度不变的情况下,温度上升到28—32℃;茶砖含梗量控制在16.5%左右,有利于冠突散囊菌的繁殖。优势菌的对数生长期一般在发花的6—9天间,到第12天时,其数量已趋于下降。但在传统发花中优势菌的对数生长期处于6—12天不等的不     

茯砖茶中冠突散囊菌及其代谢产物研究进展

冠突散囊菌是黑茶类茯砖茶发花过程的主要微生物,通过它的代谢作用不仅能够改善茶叶的品质,还可以增加许多微生物代谢活性物质。本文主要对茯砖茶中冠突散囊菌及其代谢产物研究现状进行综述,探讨了其中存在的一些问题。     

冠突散囊菌散茶发花工艺提高茯茶品质研究进展

以夏秋茶为主要原料的茯茶对促进茶业发展、提高茶叶生产效益、增加茶农收入具有重要意义。“散茶发花”工艺可克服传统“茯砖茶”工艺工序繁琐复杂、耗时长、发花质量不可控、饮用不便等缺点,为普及夏秋茶的饮用提供了新方法,为茯茶的发展奠定了技术基础。通过在茶叶上人工接种冠突散囊菌(Eurotium cristatum),并控制一定的温、湿度条件,促使该微生物生长繁殖,形成大量金黄色闭囊壳,最终形成茯茶特有的色、香、味品质。目前,利用冠突散囊菌散茶发花工艺提高茯茶品质的研究备受青睐,市场发展前景广阔。本文综述了散茶发花工艺流程及原理、散茶发花加工过程中物质的变化及对茶品质的影响,冠突散囊菌的特性及其发酵应用等内容,以期为其深入研究和开发提供帮助。     

“发花”散茶中“金花”菌的分离鉴定

从湖南益阳茶厂2008年生产的金湘益砖茶中分离纯化得到一株"金花"菌,接种至2008年一品茯茶的原料上,控制环境条件让它"发花"。从发花散茶中分离到一类"金花"菌,经过继代纯化,选取一株长势较好的"金花"菌作为供试菌株。在光学显微镜下观察菌株的有性型和无性型形态,并在扫描电镜下观察菌株的子囊孢子(有性阶段)和分子孢子(无性阶段),同时结合DNA测序,在分子水平上对分离菌株进行鉴定。根据菌株的表观形态、光学显微镜、扫描电镜和DNA序列分析,确认该菌株为冠突散囊菌(Eurotium cristatum)。     

康砖和青砖茶中散囊菌的分离、鉴定及其生物学特性研究

在砖茶加工过程中微生物对砖茶品质有重要影响。茯砖茶中的冠突散囊菌（Eurotium cristatum （Raper ＆ Fennell） Malloch ＆ Cain;也称“金花菌”）直接影响茯砖茶的品质,而康砖茶和青砖茶中却被认为不含“金花菌”。但是,有研究指出,康砖、青砖等砖茶中都含有多种真菌,康砖茶品质主要是湿热和微生物作用引起内含物变化而形成。然而这些微生物的种类、生物学特性以及它们在砖茶加工过程中的作用,未见后续报道。     

Effect of antagonistic Fusarium spp. and of different commercial biofungicide formulations on Fusarium wilt of basil (Ocimum basilicum L.)

The ability of antagonistic Fusarium spp. to control Fusarium wilt of basil caused by F. oxysporum f. sp. basilici was tested under glasshouse conditions from 1994 to 1996. Fusarium oxysporum antagonistic strain 251/2, a protoplast fusion-derived hybrid coded FI-11 and F. moniliforme strains TF4 and TF4 RB were able to decrease (P = 0.05) the incidence of Fusarium wilt significantly. Biocontrol was consistent, especially when the antagonists were applied by mixing a talc preparation of propagules in the substrate (10⁵ CFU/ml of substrate) 1–2 weeks before sowing or at sowing. Seed coating with the biocontrol strains (10⁸ CFU/g of seed) did not generally provide sufficient disease containment, whereas the combination of substrate treatment and seed coating did not improve wilt control in comparison with substrate treatment alone. Two commercial formulations, based on antagonistic F. oxysporum strains and one containing the antagonistic strain K61 of Streptomyces griseoviridis, were generally not sufficiently effective at the tested dosages.     

铝胁迫下一氧化氮对巨尾桉生长及生理的影响

酸铝抑制植物生长是全球关注的热点。以往关于酸铝胁迫的研究主要在禾本科和豆科植物上,而对经济用材林木较少。为此,本研究以巨尾桉广林9号为供试材料,在无铝（0 mmol/L）和铝胁迫（5 mmol/L）2种情况下,设置一氧化氮（NO）3个水平（0、10、500 μmol/L）,以期探究铝胁迫下外源施加NO对巨尾桉生长和生理方面的影响。试验结果表明：（1）5 mmol/L铝处理下的巨尾桉根、茎、叶生物量分别显著减少了11.57%、12.04%和37.37%,叶片叶绿素a、叶绿素a+b和类胡萝卜素含量积累也受抑制;（2）铝胁迫下叶片细胞膜透性显著增大,膜脂过氧化的产物丙二醛（MDA）显著增加了43.12%,细胞可溶性糖和蛋白含量分别显著减少了9.43%、42.27%;（3）适量添加NO （10 μmol/L）可提高铝胁迫下光合色素含量,提高最大的叶绿素a达41.23%,MDA含量明显降低了27.66%,提高可溶性糖和可溶性蛋白含量,以达到调节活性氧代谢来维持细胞膜结构稳定的效果,从而使生物量显著提高了10.19%;（4）NO浓度过高（500 μmol/L SNP）时反而对巨尾桉有毒害作用,生物量下降了15.17%,说明NO具有双重性。综上所述,铝胁迫对巨尾桉生长、渗透调节物质和抗氧化酶等生理特性均产生了抑制作用,而适当添加外源NO可以缓解铝对巨尾桉的毒害作用。     

茶多酚处理对冷藏养殖大黄鱼品质的影响

研究了经过0.2%茶多酚浸泡的养殖大黄鱼和对照组在4℃冷藏条件下25d内品质的变化。定期分析了处理组和对照组大黄鱼样品的感官特征、微生物指标（菌落总数）和化学指标（pH、TVB-N、K值）。结果表明,在冷藏过程中茶多酚处理能延长大黄鱼货架期7~8d,在货架期终点15d时,茶多酚处理组和对照组样品的细菌总数分别为10^6.12CFU/g和10^7.45CFU/g,pH值分别为6.78和6.84,TBA值分别为0.122mg/kg和0.168mg/kg,TVB-N分别为166.6mg/kg和318.7mg/kg,K值分别为27.10%和43.72%。可见,茶多酚在大黄鱼冷藏保鲜过程中能有效地抑制细菌繁殖,并减缓脂肪氧化,从而延长了大黄鱼的货架期。     

Enhancement of Xanthophyll Synthesis in Porphyra/Pyropia Species (Rhodophyta,Bangiales) by Controlled Abiotic Factors: A Systematic Review and Meta-Analysis

Red alga species belonging to the Porphyra and Pyropia genera (commonly known as Nori), which are widely consumed and commercialized due to their high nutritional value. These species have a carotenoid profile dominated by xanthophylls, mostly lutein and zeaxanthin, which have relevant benefits for human health. The effects of different abiotic factors on xanthophyll synthesis in these species have been scarcely studied, despite their health benefits. The objectives of this study were (i) to identify the abiotic factors that enhance the synthesis of xanthophylls in Porphyra/Pyropia species by conducting a systematic review and meta-analysis of the xanthophyll content found in the literature, and (ii) to recommend a culture method that would allow a significant accumulation of these compounds in the biomass of these species. The results show that salinity significantly affected the content of total carotenoids and led to higher values under hypersaline conditions (70,247.91 µg/g dm at 55 psu). For lutein and zeaxanthin, the wavelength treatment caused significant differences between the basal and maximum content (4.16–23.47 µg/g dm). Additionally, in Pyropia spp., the total carotenoids were considerably higher than in Porphyra spp.; however, the lutein and zeaxanthin contents were lower. We discuss the specific conditions for each treatment and the relation to the ecological distribution of these species.     

Studies on the influence of temperature,relative humidity and microenvironment on the natural fermentation of African oil bean seeds to ‘Ugba’

Studies on the enhancement of the traditional production of Ugba (a protein-rich fermented food) from African oil bean seeds were undertaken by fermenting the bean seeds at different temperatures, relative humidities (RH) and microenvironments. Fermentation was monitored by pH, texture, amino-nitrogen content and the viable cell count of the substrate. The 40 °C, 98% RH or the 130 m high density polyethylene (HDPE) treatment increased the fermentation microflora from ca. 106 CFU/g to ca. 108 CFU/g with high initial changes in pH (5.8–ca. 7.9) and texture (2.0 kg/cm2 to between 1.4 kg/cm2 and 0.9 kg/cm2) in 24 hours. Products with amino-nitrogen contents of between 12.00 mg N/100 g dry matter and 14.00 mg N/100 g dry matter were obtained in 3 days. The cell count of the 30 °C, 80% RH or 70 m treatment increased from 106 CFU/g to ca. 107 CFU/g and the pH increased from 5.8 to about 6.7 with a coincident decrease in the texture value from 2.0 kg/cm2 to about 1.7 kg/cm2 in 24 hours. Products with amino-nitrogen contents between 15.00 mg N/100 g dry matter and 19.2 mg N/100 g dry matter were obtained after 3 days. Changes in the fermentation indicators were not significant at p0.05 (pH and texture) and at p0.01 (amino-nitrogen) after 3 days for the 25 °C, 59.9% RH or 50 m low density polyethylene (LDPE) treatment. Products of fermentation at the combined optimal conditions (80% RH, 35 °C and 70 m HDPE) compared very well with the traditionally fermented products in terms of pH, texture and amino-nitrogen content.     

Microbiological quality of drinking water from dispensers in roadside restaurants of Bangladesh

The microbiological status of water from dispensers in different roadside restaurants of Dhaka city and Savar area was analyzed in this study. Seven samples from Dhaka and 8 samples of Savar were checked. The heterotrophic plate count was in a range of 1.0 x 10(3) CFU mL(-1) to 2.0 x 10(4) CFU mL(-1) (from new bottles), 1.0 x 10(3) to 1.5 x 10(4) CFU mL(-1) (after dispensation), and 1.5 x 10(3) CFU mL(-1) to 1.0 x l0(5) CFU mL(-1) (from serving glass). In several of the samples, the heterotrophic plate count was higher than the count in water from new bottle or after dispensation, suggesting added contamination from the serving glass. 80% of the samples were contaminated with total and fecal coliform bacteria, which render these waters unacceptable for human consumption. The samples were found to contain gram negative bacteria like E coli, Shigella sp., Klebsiella sp., Enterobacter sp., Pseudomonas sp., and Salmonella sp., which are potential pathogens and thus pose a serious threat to public health. This study elucidates the importance of monitoring the bottling companies and the restaurants and put them under strict regulations to prevent future outbreak of any water borne diseases caused by consumption of dispensed water.     

Distribution of enterococcal species and detection of vancomycin resistance genes by multiplex PCR in Tehran sewage

BACKGROUND: Enterococci are important because of their role as the leading cause of nosocomial infections which have a significant role in the dissemination and persistence of antimicrobial resistance genes. METHODS: In this study, we determined the distribution of enterococcal species in the sewage treatment plants in Iran. Furthermore, we improved a rapid and specific PCR method using primers (sodA and ddl genes) for identification of enterococci spp. RESULTS AND CONCLUSION: A total number of 712 enterococci spp. were isolated and the results showed that 56%, 24%, 12%, 4%, 2%, 1% and 1% isolates were E. faecium, E. hirae, E. faecalis, E. gallinarum, E. casseliflavus, E. mundtii and other enterococcal spp., respectively. The use of species-specific PCR was in agreement with the biochemical tests. Furthermore, multiplex PCR was developed to study the presence of vancomycin resistant genes in E. faecium or E. faecalis. The multiplex PCR appeared to be a useful, rapid and specific method for detecting and discriminating genotypes for vancomycin-resistant Enterococcus.     

Population dynamics of Xanthomonas campestris pv. vitians on different plant species and management of bacterial leaf spot of lettuce under greenhouse conditions

The population dynamics of Xanthomonas campestris pv. vitians (Xcv) was studied both externally and internally in lettuce, tomato and pepper plants. In addition, the application of bactericides during transplant production period was carried out for the management of bacterial leaf spot of lettuce under greenhouse conditions. Epiphytic populations of Xcv were recovered on leaves of lettuce plants (10⁵ CFU/g) 5 weeks after sprayed than the other plant species when inoculated with 10⁸ CFU/ml of Xcv. When plants of each crop species infiltrated with the bacterium at 10⁵ CFU/ml, the highest populations were developed in lettuce (10⁸ CFU/cm²) followed by pepper with 10⁶ CFU/cm² and tomato with 10⁵ CFU/cm² 10-days after infiltration. Application of a mixture of Maneb and Kocide or Kocide alone as a foliar spray on lettuce significantly reduced the incidence and disease severity of bacterial leaf spot by 29 and 27% respectively. Spread of the bacterium and development of the disease may partly be managed by avoiding intercropping of these plants commonly grown in close proximity to lettuce. For the management of leaf-associated populations of Xcv in lettuce, use of a mixture of Maneb and Kocide is advocated to minimize the effect of attacks.     

氟对黑茶中的冠突散囊菌和黑曲霉生长的影响

用单孢子接种,分别通过固体平板培养与液体培养,测定氟对分离自黑茶的6株冠突散囊菌和1株黑曲霉生长的抑制率、菌体生长速率和菌丝生物量,研究氟对各菌株生长的影响。结果表明：6株冠突散囊菌在含氟2 000 mg/L、黑曲霉在含氟1 800 mg/L的固体培养基中能生长。100 mg/L剂量的氟对冠突散囊菌生长的抑制率为0.76%~10.24%,对黑曲霉的抑制率达35.71%。随氟浓度的增加,生长速率变小,抑制率增大。液体培养中,100 mg/L的氟对冠突散囊菌与黑曲霉菌丝生物量的抑制率分别为34.47%、80.59%。冠突散囊菌的子囊孢子与黑曲霉的分生孢子对氟具有较强的耐受性,且两种培养方式表明冠突散囊菌比黑曲霉更耐氟。