<Emphasis Type="Italic">Rhodotorula mucilaginosa</Emphasis>, a carotenoid producing yeast strain from a patagonian high-altitude lake

The red yeast Rhodotorula mucilaginosa strain CRUB 0138 (previously identified as R. lactosa) was isolated from a high-altitude Patagonian Lake Toncek (1700 m a.s.l.), and assigned with mucilaginosa species. Its biochemical, physiological and molecular features were assessed and compared to R. mucilaginosa PYCC 5166 type strain using a polyphasic approach; in addition, biomass and carotenoid pigment production at different C/N ratios were determined in an incubator shaker. Phenetic characterization by means of 70 current physiological tests including assimilation of aldaric acids and aromatic compounds, and also the ability to grow with amino acids as sole carbon sources, was carried out. According to numerical taxonomy calculations, similarity indexes between R. mucilaginosa CRUB 0138 and PYCC 5166 type strain were 0.86 and 0.77, corresponding to a complete set of physiological tests and MSP-PCR (Mini/Micro Satellite Primed PCR; (GTG)5, M13 and (GAC)5 primers were employed) fingerprinting. Killer activity against 2 native strains, Rhodosporidium kratochvilovae and R. mucilaginosa was detected. Maximum biomass-glucose conversion efficiency (87%) and maximum carotenoid yield (2.32 mg/L) were obtained at C/N = 5 in culture medium containing 10 and 40 g/L glucose, respectively. Different C/N ratios did not influence carotenoid pigment production but low C/N enhanced biomass yield.     

转化奎宁酮为(R)-3-奎宁醇菌株的筛选及转化条件优化

(R)-3-奎宁醇是一种用于合成各类药物的重要手性砌块,以奎宁酮盐酸盐为唯一碳源,筛选得到一株能够将奎宁酮不对称还原为(R)-3-奎宁醇的菌株X15。常规生理生化鉴定和18S rDNA序列分析表明,菌株X15属于粘红酵母菌Rhodotorula mucilaginosa,定名为R.mucilaginosa X15。结果显示,菌株X15具有酮基还原能力和辅酶再生能力,在100 mL反应体系中可将奎宁酮还原为(R)-3-奎宁醇,转化率90%,ee值为88%。     

胶红酵母JB401降解脱色三苯甲烷类染料

从烟梗中分离筛选得到1株能够对三苯甲烷类染料高效脱色的微生物,经ITS-5.8S rDNA分析鉴定为胶红酵母,命名为Rhodotorula mucilaginosa JB401。全波长扫描实验结果证实染料的脱色由胶红酵母降解结晶紫引起。为了提高R.mucilaginosa JB401脱色结晶紫的能力,通过单因素试验对R.mucilaginosa JB401的培养条件进行了优化,得出菌体生长24 h后以2%接种量接入初始pH为5的脱色培养基并在37℃摇床培养,可以取得最优脱色效果,此时脱色50、100和200 mg/L的结晶紫达到90%去除率分别需要3、6和14 h。此外,胶红酵母对温度和pH良好的适应性使其具有应用于工业废水处理的潜力。     

The role of carotenoids in preventing oxidative damage in the pigmented yeast, Rhodotorula mucilaginosa

Rhodotorula mucilaginosa is an obligate aerobic yeast which contains a high concentration of carotenoid pigment. To test whether carotenoids are able to protect R. mucilaginosa against oxidative injury, yeast cells in liquid culture were incubated with duroquinone (DQ) (100 microM), a redox-cycling quinone known to generate intracellular O2-. or were grown in a hyperoxic atmosphere (80% O2) under conditions where carotenoid concentrations were altered either intracellularly or extracellularly. Neither of these oxidative challenges affected cell growth unless carotenogenesis was blocked by the addition of diphenylamine (50 microM). In the diphenylamine-treated nonpigmented cells, growth was completely inhibited by DQ and by hyperoxia. In normoxia, however, diphenylamine alone reduced growth by only 30%. The growth inhibition observed in diphenylamine-treated cells exposed to hyperoxia was primarily mycocidal rather than mycostatic since plating of these cells onto solid media revealed that only 25% of the cells were viable after 50 h of incubation when compared to plated control cells. Addition of 10 microM beta-carotene to diphenylamine-treated cells completely prevented the growth inhibition caused by either hyperoxia or DQ. Carotenoids, therefore, are able to prevent oxidant-induced cytotoxicity in R. mucilaginosa. Analysis of the absorption spectra of chloroform extracts of beta-carotene-supplemented cells showed that beta-carotene, not the endogenous carotenoid, torularhodin, was the major carotenoid present in these cells. Superoxide dismutase (SOD) activity in R. mucilaginosa was compared with that of another yeast, Saccharomyces cerevisiae by two methods: (i) activity staining of proteins separated by gel electrophoresis and (ii) measurement of inhibition of ferricytochrome c reduction. By these techniques, the R. mucilaginosa SOD activity had the characteristics of Mn-SOD. No Cu/ZnSOD activity was detected. Thus, the apparent absence of Cu/ZnSOD may make the antioxidant capability of endogenous carotenoids even more critical in preventing oxidative damage in R. mucilaginosa.     

Alterations in protein synthesis and levels of heat shock 70 proteins in response to salt stress of the halotolerant yeast Rhodotorula mucilaginosa

Responses of the halotolerant yeast Rhodotorula mucilaginosa YRH2 to salt stress was studied. Strain YRH2 was isolated from chemical industry park wastewater evaporation ponds that are characterized by large fluctuations in salinity and pH. Upon shift to high salt medium there is a shutdown of protein synthesis. Radiolabeling and separation of proteins from salt stressed and non-stressed cells identified down-regulated heat shock 70 proteins Ssb1/2p, by N-terminal sequencing and Western blotting. Ssb's role in salt stress in both R. mucilaginosa and S. cerevisiae was examined and we show that its response to salt stress and amino acid limitation is similar. Other proteins such as the heat shock 70 protein Kar2p/BiP and Protein Disulfide Isomerase were strongly induced in response to a shift to high salt in R. mucilaginosa and reacted in a manner similar to the effect of tunicamycin, a known unfolded protein response inducer. Also, assaying carboxypeptidase Y, we showed that high salt medium reduces the specific activity of the enzyme in R. mucilaginosa. It is suggested that the changes in the expression of the heat shock 70 proteins is a part of a mechanism which alleviates the damaging effects of high salt on protein folding in the yeast Rhodotorula mucilaginosa.     

Interaction between Glomus mosseae and soil yeasts on growth and nutrition of cowpea

A glass house experiment was conducted to study the interaction between the mycorrhizal fungus, Glomus mosseae and six soil yeasts (Rhodotorula mucilaginosa, Metschnikowia pulcherrima, Trichosporon cutaneum var. cutaneum, Saccharomyces cerevisiae, Cryptococcus laurentii, Debaryomyces occidentalis var. occidentalis), and their effect on growth and nutrition of cowpea. All the yeasts had a synergistic interaction with the mycorrhizal fungus and dual inoculation improved plant growth compared to single inoculation with G. mosseae alone. Nitrogen and phosphorus uptake of plants was also enhanced significantly in G. mosseae and soil yeasts combinations. Growth, N, P, chlorophyll and phenol content and yield of cowpea were highest in plants treated with G. mosseae+R. mucilaginosa. Mycorrhizal root colonization, spore numbers and population of yeasts in the root zone soil were also highest in the treatment G. mosseae+R. mucilaginosa and least in the uninoculated plants.     

Aeration controls the reduction and methylation of tellurium by the aerobic, tellurite-resistant marine yeast Rhodotorula mucilaginosa

We previously described a marine, tellurite-resistant strain of the yeast Rhodotorula mucilaginosa that both precipitates intracellular Te0 and volatilizes methylated Te compounds when grown in the presence of the oxyanion tellurite. The uses of microbes as a "green" route for the production of Te0-containing nanostructures and for the remediation of Te-oxyanion wastes have great potential, and so a more thorough understanding of this process is required. Here, Te precipitation and volatilization catalyzed by R. mucilaginosa were examined in continuously aerated and sealed (low oxygen concentration) batch cultures. Continuous aeration was found to strongly promote Te volatilization while inhibiting Te0 precipitation. This differs from the results in sealed batch cultures, for which tellurite reduction to Te0 was found to be very efficient. We show also that volatile Te species may be degraded rapidly in medium and converted to the particulate form by biological activity. Further experiments revealed that Te0 precipitates produced by R. mucilaginosa can be further transformed to volatile and dissolved Te species. However, it was not clearly determined whether Te0 is a required intermediate for Te volatilization. Based on these results, we conclude that low oxygen concentrations will be the most efficient for production of Te0 nanoparticles while limiting the production of toxic volatile Te species, although the production of these compounds may never be completely eliminated.     

胶红酵母CYJ03的体外体内抗氧化活性研究

旨在深入研究海洋源胶红酵母CYJ03的抗氧化能力,挖掘其开发成抗氧化产品的潜力.通过测定CYJ03的过氧化氢耐受性,及其发酵上清液、完整细胞和色素提取物3种不同组分的还原力、自由基清除能力和Fe2+螯合能力来评价该菌株的体外抗氧化能力;通过在罗非鱼日粮中添加CYJ03,测定罗非鱼的生长性能以及血清和肝脏的总抗氧化能力(...     

胶红酵母致真菌血症1例：临床及实验研究

目的报道1例由胶红酵母感染引起的真菌血症。方法通过对患者血培养分离致病菌,并作API 20C AUX及DNA序列测定鉴定菌种,采用抗真菌药敏纸片法对菌株进行体外药敏试验。结果患者,女性,38岁,因反复出现右乳肿块5个月行右乳肿块穿刺活检术,术后高热,发生于每日下午至夜间。2次查血真菌培养均为阳性,经菌落观察、API 20C AUX鉴定及基因测序,鉴定为胶红酵母。体外药敏试验显示对两性霉素B敏感,对伊曲康唑、氟康唑、伏立康唑耐药。未予治疗,24d后自愈。结论胶红酵母菌血症在国内罕见报道,其菌株毒力相对较低,在免疫功能正常患者中,部分病例可自愈。     

胶红酵母利用番茄渣和豆粕为原料发酵生产类胡萝卜素的研究

基于降低微生物类胡萝卜素生产成本的考虑,采用番茄渣、豆粕的纤维素酶酶解产物培养胶红酵母,以单位体积发酵液中的总类胡萝卜素浓度增量作为优化目标,先后运用逐步单因素法和均匀设计法系统性地考查了胶红酵母的总类胡萝卜素产量和增量与各个相关因素之间的关系。实验获得的总类胡萝卜素最大产量以及扣除了番茄渣中的类胡萝卜素含量而计算得到的增量分别为12.25 mg/L和10.25 mg/L。实验结果证明设计的生产工艺能够以较低的成本生产出富含类胡萝卜素的饲料,因而是经济可行的。     

2种太岁样品中微生物的分离和鉴定

目的：太岁是自然界中一种组成及分类尚不明确的生物体。采用分子生物学方法对2种不同来源地的太岁样品进行菌种分离培养和分子鉴定。方法：太岁表面经75％乙醇消毒处理后,用麦芽汁培养基分离可培养菌株,提取太岁及分离菌株基因组DNA,以之为模板,用16SrDNA、18SrDNA和ITS通用引物进行PCR扩增,扩增片段连入pMD18T载体并测序,通过序列比对对太岁菌种组成进行初步鉴定。结果：从太岁l号样品中分离到假丝酵母（Can-dida）和粘质红酵母（Rhodotorula mucilaginosa）,从太岁2号样品中分离到根癌农杆菌（Agrobacterium tumefaciens）和粘质红酵母。结论：2种来源不同的太岁样品中均存在可培养的粘质红酵母。     

Salt stress and plasma-membrane fluidity in selected extremophilic yeasts and yeast-like fungi

We have investigated changes in plasma-membrane fluidity in relation to NaCl concentrations in yeasts and yeast-like fungi that were isolated from either subglacial ice or hypersaline waters. In both of these natural environments, these organisms are exposed to low water activity, due to either high NaCl concentrations or low temperatures. Our data indicate that the fluidity of the plasma membrane can be used as an indicator of fitness for survival in extreme environments. Fungi that can survive in such extreme environments, such as Hortaea werneckii in the hypersaline waters of salterns, and Cryptococcus liquefaciens in subglacial environments, showed similar profiles of plasma-membrane fluidity in response to raised salinity. The same was seen for ubiquitous fungi, which are generally adapted for different types of stress, such as Aureobasidium pullulans and Rhodotorula mucilaginosa. Representatives of both of these groups modulated their plasma-membrane fluidity differently. When salinity exceeded their optimal range, the ubiquitous stress-tolerant species (A. pullulans, Rh. mucilaginosa) showed increased plasma-membrane fluidity, whereas in the dominant extremophiles (H. werneckii, Cr. liquefaciens), it decreased. On the other hand, the plasma membranes of the fungi with a narrow ecological amplitude (Arctic A. pullulans and Rhodosporium diobovatum) showed different responses.     

倍他洛尔立体拆分菌株的筛选与鉴定

从土壤中分离到的52株微生物中,经筛选得到一个能立体选择性水解倍他洛尔中间体的菌株。根据个体形态特征和茵落形态特征初步确定其为红酵母,根据16SDNA序列最后确定其为胶红酵母（Rhodotorula mucilaginosa）DQ832198。该菌株可用于化学酶法制备左旋倍他洛尔的研究。     

高氨氮利用酵母菌的筛选及相关酶活性

【背景】蛋白饲料的缺乏,促进了蛋白含量高、安全性能好的酵母类单细胞蛋白的研究与应用。【目的】筛选氨氮利用能力强的菌株,为单细胞蛋白的发酵提供优良菌株。【方法】从土壤、奶制品、水果采集样品分离酵母菌,根据形态学和分子生物学鉴定菌株,然后以硫酸铵为唯一氮源培养基,测定菌落大小、菌体干重、蛋白质含量,复筛氨氮利用率高的酵母菌,并对复筛菌株氨同化相关酶活性进行测定。【结果】经过形态学、分子生物学鉴定和氨氮利用能力评价,获得3株高氨氮利用的酵母菌,分别是胶红酵母(Rhodotorula mucilaginosa)、酿酒酵母(Saccharomyces cerevisiae)和戴尔有孢圆酵母(Torulaspora delbrueckii)。通过比较3株酵母菌的谷氨酸脱氢酶、谷氨酸合成酶、谷氨酰胺合成酶活性,酿酒酵母的3种酶活性最高,其次是胶红酵母。【结论】从奶酪和西瓜中分离的胶红酵母N5和酿酒酵母J1具有较强的氨氮利用能力以及酶活性,可为单细胞蛋白发酵提供优良菌株。     

Yeast carriage on the hands of Medicine students

The main focus of our study was to determine the prevalence of yeasts on the hands of Medicine students and other students not related to the Health care system. Between July 1999 and July 2000, 253 students of Medicine (163) and Engineering (90) were studied. Medicine students were grouped as basic (71), pre-clinical (62) and clinical (30). The Engineering's students were divided into three groups according to the years of study. The total yeasts carried on the hands of Medicine's students were 16%. By group the results were 7% for the basic, 19% for the pre-clinical and 30% for the clinical and the prevalence of the two last groups was higher than the first one. The Engineering's students showed 9% prevalence without differences between years of career. The yeast carriage in the clinical group was higher than the equivalent control group (10%). The species frequently encountered were Rhodotorula mucilaginosa (Rhodotorula rubra) and Candida parapsilosis, with a tendency to a higher species diversity and colony count in the pre-clinical and clinical groups. This finding could explain the high prevalence of candidemia by C. parapsilosis in our hospitals. In summary, yeast carriage, diversity and quantity in Medicine students were related to the time of being in the hospital environment.     

The yeast flora of some decaying mushrooms on trunks of living trees

Several ascomycetous and basidiomycetous yeasts were isolated from rotten mushrooms on the trunks of beech and tamarisk trees. One strain, identified as the novel species Cryptococcus allantoinivorans, assimilated allantoin as the sole carbon source. Phylogenetically it belongs to the C. laurentii complex, Papiliotrema bandonii being the closest relative. Some ascomycetous strains could not be distinguished from Pichia guillermondii, but deviated considerably in rDNA sequences. In addition to these species, both decaying mushrooms were inhabited by more common species, viz. Candida albicans, C. saitoana, Rhodotorula mucilaginosa, Trichosporon asahii, T. multisporum and T. porosum. The basidiomycetous yeasts, except R. mucilaginosa, assimilated some polysaccharides of plant origin.     

Structure-activity relationship studies on UK-2A, a novel antifungal antibiotic from Streptomyces sp. 517-02. Part 5: Roles of the 9-membered dilactone-ring moiety in respiratory inhibition

Several open-chained analogues of UK-2A, a novel antifungal antibiotic isolated from Streptomyces sp. 517-02, were prepared for structure-activity studies. The in vitro antifungal activities of these compounds against Rhodotorula mucilaginosa IFO 0001 and the inhibition of uncoupler-stimulated respiration in bovine heart submitochondrial particles (SMP) were evaluated. Oxidative potentials were measured by cyclic voltammetry. An analogue prepared from dihexyl L-glutamate showed comparable inhibitory activity as UK-2A.     

Bio-hydrolysis of used soybean oil: environmental-friendly technology using microbial consortium

Biodegradation - In this work, strains of Bacillus subtilis were inoculated in consortium with Rhodotorula mucilaginosa into spent soy oil as aiming to biological treatment and low-cost reuse. The...     

Utilization of 1-chloromethylsilatrane by Rhodotorula mucilaginosa

Abstract The imperfect yeast, Rhodotorula mucilaginosa utilized nitrogen of 1-chloromethylsilatrane (CMS) as a sole nitrogen source when grown on glucose, glycerol, methanol, ethanol and succinate. Under such conditions and at concentrations from 0.45 to 4.5 mM, CMS was a growth-limiting factor. Atomic absorption spectrometry revealed the accumulation of silicon compounds in the cultural liquid which were chloroform-insoluble in contrast to CMS. The following pathway of the partial decomposition of CMS is propoposed: CMS → chloromethylsilanethryol → bis(chloromethyldisiloxane) tetraol.