Cadmium-resistance in growing Rhodotorula sp. Y11

The uptake of cadmium and responses to this metal were studied in growing Rhodotorula sp. Y11. In presence of cadmium, Y11 showed a similar lag phase with decreased mu(max) in comparison to the control cultures in the absence of cadmium. Different changes in contents of cell elemental composition (carotenoids, total protein, total soluble sugar, and phosphate content) were observed under cadmium pressure. Growing Rhodotorula sp. Y11 took up cadmium in a biphasic mode, involving an initial energy-independent biosorption to the cell surface, followed by a slower energy-dependent intracellular accumulation. In the presence of metabolic inhibitors, intracellular cadmium uptake of growing Y11 was significantly influenced.     

Rhodotorula araucariae sp. n.

A new nitrate-assimilating yeast,Rhodotorula araucariae, isolated fromAraucaria araucana in Chile is described.     

Treatment of petroleum industry oil sludge by Rhodotorula sp.

Summary A Rhodotorula sp., isolated from soil, which showed a versttile capacity to degrade various aromatic and aliphatic hydrocarbons, was used to treat oil sludge. As a result of treatment, there was significant cecrease in BOD, COD and contents of various petroleum fractions. The susceptibility to degradation was in the following order: saturate fraction>aromatic fraction>asphaltic fraction.     

红酵母固态发酵类胡萝卜素产物稳定性的研究

探讨了红酵母固态发酵类胡萝卜素产物的干燥及储存方法;比较了真空干燥和鼓风干燥2种方法对固态发酵产物稳定性的影响;考察了光照、空气、储藏温度对固态发酵产物稳定性的影响。结果表明:在相同温度下,真空干燥(5.67±0.58)h比鼓风干燥所需时间短(9.33±0.58)h、类胡萝卜素损失小,效果也较好;光照和空气对其储藏过程中色素稳定性影响很大,30 d后类胡萝卜素损失了53%;培养物烘干后用透明塑料袋真空避光储藏效果显著,6个月后类胡萝卜素只损失19%,不抽真空损失了46%;温度对培养产物中色素稳定性影响不显著;红酵母菌株固态发酵培养产物应选择真空避光室温储藏。     

Repeated removal of cadmium and zinc from an industrial effluent by waste biomass Sargassum sp.

Waste biomass Sargassum sp. biosorbed 100% of Cd²⁺ and 99.4% of Zn²⁺ from a 3 and 98 mg l^–1 solution (pH 4.5), respectively, at the end of four serial experiments. Of the five desorbents studied in consecutive adsorption/desorption cycles, CaCl₂ 0.05 M eluted nearly 40% of both metals and decreased the biosorption in only 8% and 17% of Cd²⁺ and Zn²⁺, respectively. Although NaOH desorbent improved the heavy metal uptake from the second cycle onwards, it did not elute metals from the pre-loaded biomass.     

Responses of <Emphasis Type="Italic">Rhodotorula</Emphasis> sp. Y11 to cadmium

Some aspects of the cellular responses to cadmium were extensively investigated in the yeast Rhodotorula sp. Y11. Scanning electron microscopy indicated that accumulation of cadmium in the Y11 did not cause any visible effects on cell morphology. More than 20% yeast cells still showed viability after 15 h of cadmium accumulation under 100 mg l⁻¹ cadmium concentration, and transmission electron microscopy analysis showed that plasmolysis and thickened cell wall were not observed in all of the cells. In the presence of cadmium, the activities of superoxide dismutase (SOD) and catalase (CAT) were all greater than the control, but the increase was in a dose-independent manner. Changes in SOD and CAT activities were also dependent on the time of exposure. Therefore, it suggests that antioxidative defenses play an important role in cadmium tolerance in Rhodotorula sp. Y11. Nondenaturing polyacrylamide gels revealed only one SOD isoforms in Y11 even under exposure to cadmium.     

逆境对红酵母发酵生产类胡萝卜素的促进作用

类胡萝卜素广泛存在于细菌、藻类、真菌和植物中,是一类具有重要的生理保健功能的呈黄色、橙红色或红色的多烯类化合物。考察了不同逆境条件,包括低温、低温处理时间、酸处理及高浓度盐处理对促进一株红酵母(Rhodotorulasp.)发酵生产类胡萝卜素的影响,并利用响应面分析方法研究了其交互作用。结果表明,低温,酸处理、高浓度盐的影响以及低温和酸处理、低温和高浓度盐以及低温处理时间和酸处理的交互作用对类胡萝卜素产量的影响均显著,在温度为15℃处理48 h,pH3.5,NaCl浓度为2 mol/L的条件下,类胡萝卜素最高产量达到31.04 mg/L,说明逆境对红酵母发酵生产类胡萝卜素具有促进作用。     

红酵母产类胡萝卜素固态发酵工艺条件的研究

该文研究了红酵母菌株D固态发酵产类胡萝卜素的培养基配方和发酵条件,得到初步优化的培养基为:啤酒糟∶豆粕∶麸皮=1∶3∶2.通过正交试验优化的培养条件是培养基含水量为60%,装量为6/150(即6g干基按设计的初始含水量用盐溶液配好后装于150ml三角瓶中),接种龄为24h,无机盐为0.5g/L MgSO4,其色素产量为14.2μg/g干基。色素产量随接种量增大而增大,细胞生物量、类胡萝卜素产量和含量均随发酵时间的增加逐渐增加,在96h分别达到最大值67.75mg dry-cell/g干基、9.88μg/g干基、145.80μg/g dry-cell,确定其最佳发酵周期为96h。     

Rhodotorula sp. and Trichosporon sp. are more Virulent After a Mixed Biofilm

Mycopathologia - Rhodotorula spp. and Trichosporon spp. are opportunistic pathogens, and although an association between these two species in the same infection appears to be uncommon, it has been...     

Isolation and application of Gordonia sp. JC11 for removal of boat lubricants

Boat lubricants are continuously released into the marine environment and thereby cause chronic oil pollution. This study aims to isolate lubricant-degrading microorganisms from Thai coastal areas as well as to apply a selected strain for removal of boat lubricants. Ten microorganisms in the genera of Gordonia, Microbacterium, Acinetobacter, Pseudomonas, Brucella, Enterococcus and Candida were initially isolated by crude oil enrichment culture techniques. The lubricant-removal activity of these isolates was investigated with mineral-based lubricants that had been manufactured for the 4-stroke diesel engines of fishing boats. Gordonia sp. JC11, the most effective strain was able to degrade 25-55% of 1,000 mg L(-1) total hydrocarbons in six tested lubricants, while only 0-15% of the lubricants was abiotically removed. The bacterium had many characteristics that promoted lubricant degradation such as hydrocarbon utilization ability, emulsification activity and cell surface hydrophobicity. For bioaugmentation treatment of lubricant contaminated seawater, the inoculum of Gordonia sp. JC11 was prepared by immobilizing the bacterium on polyurethane foam (PUF). PUF-immobilized Gordonia sp. JC11 was able to remove 42-56% of 100-1,000 mg L(-1) waste lubricant No. 2 within 5 days. This lubricant removal efficiency was higher than those of free cells and PUF without bacterial cells. The bioaugmentation treatment significantly increased the number of lubricant-degrading microorganisms in the fishery port seawater microcosm and resulted in rapid removal of waste lubricant No. 2.     

Acinetobacter sp. Y1的氨氮去除性能及其关键酶活性

【目的】研究Acinetobacter sp.Y1的氨氮(NH_4~+-N)去除性能及其关键酶的提取与酶活性。【方法】以柠檬酸钠为碳源,硫酸铵为氮源,研究菌株Y1的NH_4~+-N去除性能;采用正交实验优化超声波破碎法提取粗酶的条件,SDS-PAGE分析比较渗透压休克法和超声波破碎法获得的粗酶;检测关键酶——羟胺氧化还原酶(HAO)、亚硝酸盐还原酶(NIR)、硝酸盐还原酶(NAR)的酶活性。【结果】24 h内菌株Y1的菌密度(OD600)可达1.280,对NH_4~+-N、总氮(TN)和COD的降解率分别达到98%、94%和92%,硝化过程中羟胺、亚硝酸盐氮、硝酸盐氮不积累,反硝化产生N2;超声波破碎法提取粗酶的最佳工作条件为:破碎功率50 W,工作与间歇时间分别为4 s和7 s,OD600为1.250,总工作时间20 min,关键酶HAO、NIR和NAR的比活力分别为0.011、0.002和0.018 U/mg;渗透压休克法得到的HAO比活力是0.067 U/mg。【结论】Acinetobacter sp.Y1能同时高效去除NH_4~+-N、TN和COD。优化超声波破碎法提取粗酶的条件,检测到HAO、NIR和NAR的酶活性,且渗透压休克法比超声波破碎法更适合用来提取HAO。     

红酵母产类胡萝卜素提取工艺的优化研究

目的:从提取溶剂及提取条件等方面对红酵母产类胡萝卜素提取工艺进行了优化研究。方法:用单因子实验对提取溶剂进行了筛选;用析因试验对提取条件进行了分析研究;通过最陡爬坡实验和中心组合设计实验,优化得到了最佳的类胡萝卜素提取条件。结果:结果表明丙酮和二甲亚砜组成的复合体系是理想的提取溶剂。溶剂添加量、提取温度、提取时间、丙酮与二甲亚砜组分比例都对红酵母产类胡萝卜素提取产生一定影响,其中溶剂添加量和丙酮与二甲亚砜组成比例的影响最为显著(P<0.001)。最佳优化提取条件为:溶剂添加量为42.66%(V/V),丙酮与二甲亚砜组成比例为62.47%(V/V),温度为20℃,提取时间为90min,在此条件下红酵母产类胡萝卜素的最大提取量为5.51μg/ml。结论:实验得到了红酵母发酵产类胡萝卜素溶剂提取条件的一个非常合适的模型。     

Characterization of new biosurfactant produced by Klebsiella sp. Y6-1 isolated from waste soybean oil

To obtain predominant bacteria degrading crude oil, we isolated some bacteria from waste soybean oil. Isolated bacterial strain had a marked tributyrin (C4:0) degrading activity as developed clear zone around the colony after incubation for 24h at 37 degrees C. It was identified as Klebsiella sp. Y6-1 by analysis of 16S rRNA gene. Crude biosurfactant was extracted from the culture supernatant of Klebsiella sp. Y6-1 by organic solvent (methanol:chloroform:1-butanol) after vacuum freeze drying and the extracted biosurfactant was purified by silica gel column chromatography. When the purified biosurfactant dropped, it formed degrading zone on crude oil plate. When a constituent element of the purified biosurfactant was analyzed by TLC and SDS-PAGE, it was composed of peptides and lipid. The emulsification activity and stability of biosurfactant was measured by using hydrocarbons and crude oil. The emulsification activity and stability of the biosurfactant showed better than the chemically synthesized surfactant. It reduced the surface tension of water from 72 to 32 mN/m at a concentration of 40 mg/l.     

Characterization of levan produced by Serratia sp.

Levan was produced by a newly isolated bacterium from soil, taxonomically identified as a Serratia sp. This is the first report of levan production by Serratia sp. The levan was digested by levanase, which cannot hydrolyze β-2,1 linkages and the remaining substrate was analyzed by NMR. It was found that this levan had less β-2,1 linkage than other microbial levans, and that the structure was quite different from the levan produced by other bacteria such as genus Bacillus.     

Properties of an enzymatic complex active in sulfite and thiosulfate oxidation by Rhodotorula sp.

An enzymatic complex from Rhodotorula was characterized and it was indicated that it possessed thiosulfate-oxidizing activity, forming tetrathionate as well as sulfite oxidase activity. Both activities coupled with ferricyanide and native cytochrome c but no with mammalian cytochrome c. Activities of these enzymes were inhibited by thiol inhibitors. Chelating agents did not affect thiosulfate oxidizing activity and only moderately inhibited sulfite oxidase. Both activities disappeared after treatment with proteolytic enzymes or sodium deoxycholate which indicates an essential role played not only by protein but also by phospholipids in the enzymatic activity of the complex. Thiosulfate oxidizing enzyme had a K _m for thiosulfate of 0.16 mM with ferricyanide as electron acceptor and of 14 M with native cytochrome c and of 0.34 mM for ferricyanide. Optimum pH for this activity was 7.8. Other properties of this enzyme were similar to those of thiobacilli and heterotrophic bacteria. The activity of sulfite oxidase was inhibited by 50% with 10 M AMP. The K _m values of this enzyme were 1 mM with ferricyanide as electron acceptor and 60 M with native cytochrome c for sulfite and 0.42 mM for ferricyanide. The enzyme did not show a specific optimum pH value with ferricyanide as electron acceptor. However, with native cytochrome c optimum pH was 7.8 for its activity. In many properties the sulfite oxidase from Rhodotorula was similar to the enzyme from Thiobacillus ferrooxidans, T. concretivorus, T. thioparus and T. novellus.Abbreviations CSH reduced glutathion - APS reductase, adenosine-S-phosphosulfate reductase - pHMB p-hydroxymercuribenzoate - NEM N-ethylmalcimide - TCA trichloroacetic acid - PPO 2,5-diphenyloxazole - POPOP 2,2-p-phenylen-bis 5-phenyloxazol     

Meningitis caused by Rhodotorula.

A case of rhodotorula meningitis in a 21 year old male compromised with acute lymphoblastic leukemia is reported. The yeast was identified as Rhodotorula rubra (Demme) Lodder.