酵母菌絮凝的分型及其生理生化特性的研究

通过对410余株酵母菌进行絮凝测定,从中筛选到5株强絮凝菌。依据不同糖对其絮凝水平的抑制,将5株强絮凝菌分为Flo 1型和NewFlo型。对这两种絮凝型菌株的相关生理生化特性进行了研究。结果表明,Flo 1型菌絮凝只受甘露糖抑制,它对高温(70℃)、蛋白酶E、胰蛋白酶敏感,而对蛋白酶K、糜蛋白酶、Ca\+\{2+\}\,pH有一定耐受性。NewFlo型菌絮凝受甘露糖等多种糖抑制,它对高温(70℃)、各种蛋白酶、Ca\+\{2+\}、pH均较敏感。这两种类型菌株絮凝的最适Ca\+\{2+\}浓度为10mmol/L～1mol/L,最适pH为3.0～45。     

水稻化感作用及其生理生化特性的研究

选用具有强化感作用的6个水稻品种为供体,大田稗草为受体,研究了水稻化感作用及生理生化特性,结果表明,提高水稻叶片浸提液浓度,可以相应增强对稗草生长的抑制效果,这种抑制效果与杂草的种植密度呈负相关;化感水稻叶片浸提液能显著抑制物质稗草体内超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性,从而影响其生长;苯丙氨酸氨解酶（PAL）的活性大小与酚类物质的含量吴正相关;多种酚类物质的化感作用之间可能是增效的,也可能是拮抗的。     

速生杨与钻天杨生理生化特性比较研究

测定了速生杨与钻天杨的一系列生理生化特性,结果表明：速生杨的叶绿素、脯氨酸、脱落酸、抗坏血酸、可溶性糖含量、硝酸还原酶和过氧化物酶活性均高于钻天杨。但可溶性蛋白含量低,且在不同温度胁迫下细胞膜通透性较高。     

盐胁迫对Frankia 生长和生理生化特性的影响

研究了盐胁迫(10～50 g·L-1 NaCl)对从杨梅[Myrica rubra (Lour.) Sieb. et Zucc.]、木麻黄(Casuarina spp.)、桤木(Alnus spp.)和福建胡颓子(Elaeagnus oldhami Maxim.)根瘤中分离出的11株Frankia菌株的生长和生理生化特性的影响.结果表明,在离体培养条件下,分离自木麻黄和桤木根瘤的Frankia菌株耐盐性最强,其次是来源于福建胡颓子根瘤的Frankia菌株,而从杨梅根瘤中分离得到的Frankia菌株耐盐性最弱.在盐胁迫条件下, Frankia菌株的形态和生理生化特征也发生相应变化孢囊和泡囊数量增加、菌丝变细或变粗、固氮酶活性增加、营养源利用率下降.     

铜对马铃薯块茎产量与生理生化特性的影响

铜对马铃薯块茎产量与生理生化特性的影响白嵩吕芳芝＊白宝璋李秀坤刘志清＊＊陈文荣（吉林农业大学,长春１３０１１８）ＥＦＦＥＣＴＳＯＦＣＯＰＰＥＲＯＮＴＵＢＥＲＹＩＥＬＤＡＮＤＰＨＹＳＩＯ┐ＬＯＧＩＣＡＬＡＮＤＢＩＯＣＨＥＭＩＣＡＬＣＨＡＲＡＣ┐ＴＥＲ...     

S3307对烟草幼苗某些生理生化特性的影响

烟草种子经Ｓ３３０７浸种后,其幼苗根系活力、根干重,叶绿素和可溶性蛋白质含量,光合速率,过氧化物酶,过氧化氢酶和硝酸还原酶的活性都有提高。     

采后草莓果实的生理生化特性

综述了草莓果实采后生理生化变化的研究现状及果实成熟的分子生物学研究进展.     

Cd对桑叶品质,生理生化特性的影响及其机理研究

土壤中不同浓度的Ｃｄ对桑叶产量、品质、生理生化特性的影响以及Ｃｄ在桑叶亚细胞各组分中分布量的研究表明,当土壤Ｃｄ浓度小于２２．３ｍｇ·ｋｇ－１时,桑叶产量、可溶性糖和含氯化合物含量高于或接近对照;桑叶叶绿素含量、细胞膜透性和超氧化物歧化酶、过氧化物酶及蛋白酶的活性无明显影响或有促进．当土壤Ｃｄ浓度大于２２．３ｍｇ·ｋｇ－１时,Ｃｄ对桑叶产量、营养物质含量、生理生化作用的影响随之明显,并表现其毒害作用．根据Ｃｄ在桑叶亚细胞组分中的分布规律．对其影响机理进行了探讨,说明桑树是一种具有一定耐Ｃｄ性的经济作物．因此,可利用其耐Ｃｄ性,在被Ｃｄ污染土地上种植桑树．     

不同微生物的α—乙酰乳酸脱羧酶的生理生化特性的研究

分析测定了不同微生物的α-乙酰乳酸脱羧酶（ALDC）酶活力,结果表明不同来源的ALDC酶力有较大差异,酶反应速度曲线存在明显差异;酶反应体系的pH对ALDC酶活力有明显的影响,如乳酸乳球菌的ALDC酶反应最适PH为6．6,而产气气杆菌的ALDC酶反应的最适PH为5．8,酶反应体系中加入不同浓度的亮氨酸,缬氨酸和异亮氨酸对不同来源的ALDC酶活性有较明显的影响。     

茄子雄性不育系与保持系生理生化特性比较分析

以赤茄（Solanum integrifolium）和栽培品种远缘杂交选育得到的核质互作型雄性不育系05-506及其保持系05-507为材料,测定并分析了叶片激素、叶绿素、游离总氨基酸、可溶性糖含量及光合特性。结果表明,茄子不育系苗期叶片中IAA和GA3含量低于保持系,ZR含量高于保持系,ABA／（IAA＋ZR＋GA3）比值约为保持系的1.3倍;不育系叶绿素含量幼苗期低于保持系,盛花期和保持系相近,结果期高于保持系;可溶性糖和游离总氨基酸含量高低随光合速率的变化而变化．幼苗期C／N比值低,盛花期C／N比值增大,碳水化合物代谢加强,结果期C／N比值下降,但不育系下降幅度较保持系少。不育系与保持系的Pn日变化均呈双峰曲线,即有光合“午休”现象;Pn值顺序不育系为幼苗期＜盛花期＜结果期,保持系为幼苗期＜结果期＜盛花期;不育系在营养生长和生殖生长时期的光饱和点均高于保持系,光补偿点在幼苗期和盛花期高于保持系,但结果期比保持系低。     

Breeding of flocculent industrial alcohol yeast strains by self-cloning of the flocculation gene FLO1 and repeated-batch fermentation by transformants

A nonflocculent industrial polyploid yeast strain, Saccharomyces cerevisiae 396-9-6V, was converted to a flocculent one by introducing a functional FLO1 gene at the URA3 locus. The flocculent strain FSC27 obtained was a so-called self-cloned strain, having no bacterial DNA. FSC27 cells could be easily recovered for reuse from fermentation mash without any physical energy. The strain produced a concentration of alcohol as high as 396-9-6V, although the fermentation rate of FSC27 was slightly lower than that of 396-9-6V. When uracil was added to the medium or when URA3 was reintroduced into FSC27 (named FSCU-L18), the fermentation rate and the growth rate increased, and the ethanol concentration produced was higher than that produced by the parent strain. The stable flocculation and high ethanol productivity were observed by using FSCU-L18 during 10 cycles of repeated-batch fermentation test.     

Characterization of oxygen uptake and mass transfer in flocculent yeast cell cultures with or without a flocculation additive

Summary The effect of solids concentration and the presence of the charged polymeric additive Magna Floc LT25 on gas-liquid oxygen transfer and oxygen consumption rates have been evaluated for flocculent yeast cells grown in batch fermentations. No significant differences were found for oxygen consumption due to the presence of the additive. Low biomass concentrations have a positive effect on oxygen transfer rate, when the additive was present in the medium. For biomass concentrations above 1 g/L, an increase in biomass concentration leads to a reduction on oxygen transfer rates regardless of the presence of the additive.     

Construction of flocculent industrial yeast by the yeast flocculation gene <Emphasis Type="Italic">FLO1</Emphasis>

The structure gene FLO1 from Saccharomyces cerevisiae W303-1A encoding a flocculation protein and the G418 resistance gene kanMX from plasmid pUG6 were amplified by PCR method. The expression vector pYX212 harboring FLO1 gene and kanMX gene was transformed into Angel yeast. The transformant Angel yeast F6 was obtained and showed strong and stable flocculation ability during 20 batches inoculation. And the flocculation ability of the transformant Angel yeast F6 showed no difference in the medium with the initial pH ranging from 3.5 to 6.0. Noteworthily, the flocculation onset of the transformant strain was in the early stationary growth phase, not coincident with the glucose depletion in the cultural medium. And in the experiment the ethanol yield and other properties of the transformant Angel yeast F6 were similar to those of the wild-type strain, although its fermentation time was a little slower comparing with the wild-type strain. Those would be potential application for yeast cells to separate and recycle in the fuel ethanol industry.     

Biochemical and physiological studies of the yeast virus-like particle.

A study was made of the virus-like particle (VLP) of Saccharomyces cerevisiae S7. This strain contains elevated amounts of P1 double-stranded ribonucleic acid (dsRNA) but no P2 dsRNA. The amount of dsRNA contained in cells grown on a fermentable carbon source (glucose) was compared with that in cells grown on a nonfermentable carbon source (ethanol). It was found that ethanol-grown cells contain higher levels of dsRNA than glucose-grown cells. In the former, the amount of dsRNA increased during the logarithmic phase of growth, whereas in the latter it increased during the transition from the logarithmic to the stationary phase. A method was devised to isolate VLPs from these cells by using CsCl gradients, and the yield was assessed by monitoring the recovery of dsRNA. Three proteins were found to be tightly associated with these particles. They have molecular weights of 75,000, 53,000, and 37,000. Together they account for almost all of the coding capacity of the P1 dsRNA that the VLP contains.     

Unusual flocculation characteristics of the yeast Candida famata (Debaryomyces hansenii)

Candida famata NCYC 576 cells aggregated throughout growth in YEPD. Aggregates were dispersed by Pronase E, EDTA or specific sugars. EDTA-dispersed cells reaggregated after calcium ion addition. Unlike Saccharomyces cerevisiae, C. famata cells lost the ability to flocculate with repeated EDTA washings. These cells regained flocculation when resuspended in the first washing solution after calcium addition. Candida famata NCYC 576 aggregation is consistent with lectin-mediated yeast flocculation, where lectins are not surface-anchored, as in S. cerevisiae but attached to cells only by lectin action.     

The flocculation of wine yeasts: biochemical and morphological characteristics in Kloeckera apiculata

The floc-forming ability of flocculent strains of Kloeckera apiculata, isolated from musts, was tested for susceptibility to proteinase and sugar treatments. Three different flocculation phenotypes were discriminated by protease digestion, whereas the inhibition of flocculation by sugars distinguished two definite patterns: one mechanism of flocculation involved a galactose-specific protein and the other a broad-specificity lectin. SEM and TEM observation of the cell surface of two different Kloeckera strains revealed fine fibrils and a diffuse structure at the point of contact in one strain, and thick masses of mucus on the cell wall of the other strain.     

On-line measurement and analysis of yeast flocculation

The ability of yeast to flocculate is important in different separation processes, especially in the beer industry. Because of the regulation purposes, there is a need for online monitoring. With the presented measuring set-up, consisting of a peristaltic pump, a photometer, and a computer, it is possible to determine the onset of flocculation as well as to follow flocculation intensity and the concentration of nonflocculated cells. It was found that for the yeast strain Saccharomyces cerevisiae ZIM 198 the decrease of nonflocculated cells (after flocculation has occurred) during the exponential growth can be described by an exponential equation for the first-order process, whereas the increase of free cells due to dispersion of the flocs during the stationary phase follows the form of the growth curve. It was also demonstrated that the absorbency profiles of yeast sedimentation can be described by the second-order equation suggested by Stradford and Keenan for the decrease of cell concentration during sedimentation. (c) 1997 John Wiley & Sons, Inc.