Isolation and identification of crude oil-degrading yeast strains from Khafji oil field,saud Arabia

Twenty five yeasts isolated were isolated from Khurais oil field in Saudi Arabia and assayed to evaluate their biodegradability. Only five isolates (namely, A1, A2, A3, A4 and A5) showed potential use of oil as sole carbon source. During incubation period, highest growth rate were recorded for A1, A2 and A3 isolates. Low growth distinguished A4 isolate; A5 isolate could not degrade oil.Spectrophotometrical analysis for four yeast isolates biodegradation activities indicated that, A1 isolate was superior for oil degradation (61%) comparing with A4 isolate which reflected lowest degradation % (33%). A2 and A3 isolates showed moderate biodegradation activity (56 and 51% respectively).D1/D2 domain of the 26S rRNA gene sequence was used as molecular marker to identify five yeast isolates. After comparing 26S rRNA gene sequences of five yeast isolates with highly similarity isolates, five yeast isolates (A1, A2, A3, A4 and A5)were submitted to database as Candida tropicalis (MW488263), Candida tropicalis (MW488264), Rhodotorula mucilaginosa (MW488265) and Rhodosporidium toruloides (MW488266) respectively. Using OXF1/ACR1 primer, specific lipase gene amplicon with 250 bp were detected with in all four yeast isolates.     

Degradation of Toluene Hydrocarbon by Isolated Yeast Strains: Molecular Genetic Approaches for Identification and Characterization

Removal of petroleum benzene, toluene, and xylene compounds from the environment is necessary to ensure quality life. In this research, 41 yeasts were isolated from oily soils. Among them, nine yeasts named KKUs (A5, A6, A12, A20, A23, A24, A26, A29, and A38) were selected based on their use of benzene, toluene, and xylene as a sole carbon and energy source. Based on their growth rates, all selected yeasts displayed a high efficiency for toluene degradation, but had no ability to degrade benzene and a low ability to degrade xylene, except A29 and A38, which could not degrade xylene. HPLC analysis for toluene removal indicated that A6, A12, A20, A23, A24, and A26 almost completely removed the toluene compound after 3 days of incubation (92.74, 94.61, 95.05, 91.74, 91.85, and 97.29%, respectively). In addition, strains A29 and A38 showed moderate degradation (88.29 and 85.30%, respectively), while the ability of A5 was low (39.00%). The isolates were identified based on amplifying and sequencing the D1/D2 domain of the 26S rRNA gene. Alignments and comparisons of the 26S rRNA gene sequences of the isolates with those available in GenBank, plus phylogenetic analysis, proved isolates as Rhodotorula lactose KKU-A5, Rhodotorula nymphaeae KKU-A6, Rhodotorula graminis KKU-A12, Rhodotorula minuta KKU-A20, Exophiala dermatitidis KKU-A23, Candida davisiana KKU-A24, Rhodotorula slooffiae KKU-A26, Rhodotorula mucilaginosa KKU-A29, and Rhodosporidium diobovatum KKU-A38. Random amplified polymorphic DNA-PCR fingerprinting was accomplished within seven toluene-degrading red yeasts (A5, A6, A12, A20, A26, A29, and A38). The results indicated no correlation between the random amplified polymorphic DNA profile and the geographic origin of the isolates.     

Characterization of the yeast flora present in some Turkish high-sugar products

In this study, 129 Turkish high-sugar products were examined in terms of their yeast flora and 73 representative strains were isolated. Yeast isolates were identified at species level by using Apilab Plus (bioMérieux, France), a specific computer program developed for ID 32C strips (bioMérieux, France). While one of the isolates could be identified at genus level as Aureobasidium, 66 of them were identified as 21 species belonging to 8 different genera. The distribution of these isolates were as follows: Candida (38), Rhodotorula (8), Zygosaccharomyces (7), Cryptococcus (6), Saccharomyces (3), Debaryomyces (2), Pichia (1) and Torulaspora (1). Approximately 70% of the isolates were found to have the ability to grow on media with 50% (w/w) glucose. Hence, they were characterized as xerotolerant strains. Although Zygosaccharomyces rouxii is known as the most xerotolerant yeast species, only two strains of Z. rouxii could be isolated from Turkish high-sugar foods. During identification studies, it was observed that ID 32C test strips should certainly be supported by morphological and physiological tests for obtaining more reliable identification results. If not, closely related yeast species such as anamorph and telemorph forms can not be distinguished.     

Low-temperature microbial degradation of crude oil products differing in the extent of condensation

Out of the 30 strains capable of oil degradation at 4-6 degrees C, four were selected by the ability to degrade 40% of the oil substrate present in the growth medium: Rhodococcus spp. DS-07 and DS-21 and Pseudomonas spp. DS-09 and DS-22. We studied the activity of these strains as degraders of oil products of various condensation degrees (crude oil, masut, petroleum oils, benzene resins and ethanol-benzene resins) at 4-6 degrees C. The maximum degrees of degradation of masut and ethanol-benzene resins were observed in Pseudomonas spp. DS-22 (17.2% and 5.2%, respectively). The maximum degradation of petroleum oils and benzene resins was observed in Rhodococcus spp. DS-07 (40% and 16.6%, respectively). The strains provide a basis for developing biodegrader preparations applicable to bioremediation of oil-polluted sites under the conditions of cold climate.     

Characterization of yeast strains of the genera candida, Hansenula, Kluyveromyces, Pichia, Rhodotorula, and Saccharomyces by mixed-dye fluorometry.

An analytical method in which we used the selective adsorption of several fluorophores by yeast cells is described. The suitability of using binary mixtures of 1-pyrene butyric acid, 3,6-dimethylamino acridine, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid, and rhodamine B isothiocyanate for the characterization and identification of microorganisms was tested with 98 yeast strains belonging to the genera Candida, Hansenula, Kluyveromyces, Pichia, Rhodotorula, and Saccharomyces. The application of multivariate statistical methods and pattern recognition methods to the allocation of the yeast strains into genus-species-strain structures and to a comparison of fluorescence data sets for differentiation and identification purposes showed the usefulness of the method.     

Isolation and characterization of ethanol-producing yeasts from fruits and tree barks

Aims:  Isolation and identification of yeasts converting xylose to ethanol.
Methods and Results:  A total of 374 yeasts were isolated from a variety of rotten fruits and barks of trees. Out of these, 27 yeast strains were able to assimilate xylose and produce 0·12–0·38 g of ethanol per gram of xylose. Based on phylogenetic analysis of D1/D2 domain sequence of LSU (Large Subunit) rRNA gene and phenotypic characteristics the ethanol-producing strains were identified as member(s) of the genera Pichia, Candida , Kluyveromyces, Issatchenkia, Zygosacchraomyces , Clavispora, Debaryomyces , Metschnikowia , Rhodotorula and Cryptococcus.
Conclusion:  Yeast strains producing ethanol from xylose have been isolated from a variety of rotten fruits and barks of trees and identified.
Significance and Impact of the Study:  Environmental isolates of yeasts which could convert xylose to ethanol could form the basis for bio-fuel production and proper utilization of xylan rich agricultural and forest wastes.     

Physiological properties of some yeast strains

Twenty yeast strains have recently been isolated in pure cultures from natural and industrial sources and identified based mainly on physiological properties. The majority of the strains (15) are alcohologenic belonging to the genus Saccharomyces and comprise two brewer's (beer) yeast strains (S. carlsbergensis= S. uvarum A and B), two baker's yeast strains (S. cerevisiae CA and CP), one spirit yeast strain (S. cerevisiae CF) and ten wine yeast strains (S. cerevisiae var. ellipsoideus = S. ellipsoideus 1, 3, 4, 6, 8 and 9; S. oviformis 2, 5 and 7; and S. uvarum 10). The other 5 yeast strains belong to different species: Kloeckera apiculate, Candida mycoderma (Mycoderma vini), Pichia membranaefaciens, Rhodotorula glutinis and Torulopsis holmii, respectively.     

Diversity and characterization of cultivable oleaginous yeasts isolated from mangrove forests

A total of 198 yeasts were isolated from 140 samples collected from 7 mangrove forests in 4 provinces of Thailand, and were found to belong to 30 genera, 45 described species and at least 12 undescribed species based on their 26S rRNA (D1/D2 domain) gene sequence. The most prevalent species was Candida tropicalis, followed by Candida pseudolambica and Rhodosporidium paludigena. Lipid accumulation, as determined by Nile red staining, of the isolated yeasts revealed that 69 and 18 strains were positive and strongly positive, respectively, while quantitative analysis of the intracellular lipid accumulated in the latter indicated that 10 of these strains, Pseudozyma tsukubaensis (YWT7-2 and YWT7-3), Rhodotorula sphaerocarpa (YWW6-1 and SFL14-1SF), Saitozyma podzolica (YWT1-1, NS3-3 and NS10-2), Prototheca zopfii var. hydrocarbonea OMS6-1 and Prototheca sp. (YMTW3-1 and YMTS5-2), were oleaginous. In this study we found that under nitrogen depletion condition (155 C/N ratio) Pseudozyma tsukubaensis YWT7-2 accumulated the highest level of intracellular lipid at 32.4% (w/w, dry cell weight), with a broadly similar fatty acid composition to that in palm oil.     

Rhodotorula pinicola sp. nov., a basidiomycetous yeast species isolated from xylem of pine twigs

Three pink-colored yeast strains 3-1-3, 10-3-3 and 19-3-3 were isolated from xylem of surface-sterilized twigs of Pinus tabulaeformis collected from Dongling Mountain, Beijing, in different seasons. These strains were identified as Rhodotorula minuta (Saito) F.C. Harrison by conventional taxonomic characterization. However, molecular phylogenetic analysis based on internal transcribed spacer region (including 5.8S rDNA) and large-subunit rDNA D1/D2 domain sequences indicated that they represent a novel basidiomycetous yeast species, for which Rhodotorula pinicola is proposed (type strain: AS 2.2193(T)=CBS 9130(T)). The new species was most closely related to Rhodotorula laryngis Reiers?l in the R. minuta complex.     

Anti-Candida activity of four antifungal benzothiazoles

Abstract Anti- Candida activity of 6-amino-2- n -pentylthiobenzothiazole (I), benzylester of (6-amino-2-benzothiazolylthio)acetic acid (II) and of 3-butylthio-(1,2,4-triazolo)-2,3-benzothiazole (III) was followed and compared to that of 2-mercaptobenzothiazole (IV). I and II exhibited good activity against the C. albicans yeast form, similar to IV. They were inhibitorily active against other Candida strains, IC₅₀ values being of the order of 10⁻⁵ M, which means better activity than IV. Compound I also exhibited inhibitory activity on germ-tube formation and mycelial growth in the C. albicans strains, while II, III and IV were not active in these tests. III was the least active form of the compounds tested, IC₅₀ values being of the order of 10⁻⁴ M. All the compounds tested were highly active on a nystatin-resistant C. albicans mutant, with IC₅₀s of the order of 10⁻⁶ M−10⁻⁵ M.     

八株芽孢杆菌菌株的分类及固氮活性的测定

从8个省市的不同土壤分离了200个菌株,筛选出8株（JR₁,JR₂,JR₅,ZZ₃,ZZ₁₂,ZZ₁₆,M₁,K₄）能在无氮培养基上生长良好的典型的芽抱杆菌,其中6株（JR₁,JR₂,JR₄和ZZ₃,ZZ₁₂,ZZ     

Use of bacterial acc deaminase to increase oil (especially poly aromatic hydrocarbons) phytoremediation efficiency for maize (zea mays) seedlings

Oil presence in soil, as a stressor, reduces phytoremediation efficiency through an increase in the plant stress ethylene. Bacterial 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, as a plant stress ethylene reducer, was employed to increase oil phytoremediation efficiency. For this purpose, the ability of ACC deaminase-producing Pseudomonas strains to grow in oil-polluted culture media and withstand various concentrations of oil and also their ability to reduce plant stress ethylene and enhance some growth characteristics of maize and finally their effects on increasing phytoremediation efficiency of poly aromatic hydrocarbons (PAHs) in soil were investigated. Based on the results, of tested strains just P9 and P12 were able to perform oil degradation. Increasing oil concentration from 0 to 10% augmented these two strains population, 15.7% and 12.9%, respectively. The maximum increase in maize growth was observed in presence of P12 strain. Results of high-performance liquid chromatography (HPLC) revealed that PAHs phytoremediation efficiency was higher for inoculated seeds than uninoculated. The highest plant growth and PAHs removal percentage (74.9%) from oil-polluted soil was observed in maize inoculated with P12. These results indicate the significance of ACC deaminase producing bacteria in alleviation of plant stress ethylene in oil-polluted soils and increasing phytoremediation efficiency of such soils.     

醇化烟叶酵母菌分离鉴定及其生物学特性研究

采用涂布培养法和富集培养法对醇化烟叶样品中酵母菌进行了分离,富集培养法分离到23株,涂布培养法分离到6株。29株酵母菌的生物学特性研究表明,其中果胶酶、蛋白酶、淀粉酶、脂酶、纤维素酶、酚类利用、木质素利用、尼古丁降解、发酵产物气味等试验呈阳性的菌株数分别是1、10、0、3、10、22、1、21和29株。利用ATB系统,将ATY1、ATY8和ATY27等3株酵母菌分别鉴定为黏红酵母(Rhodotorula glutinis)、罗伦隐球酵母(Cryptococcus laurentii)和粗壮假丝酵母(Candida valida),各菌株鉴定结果的符合率分别为99.4%、98.2%和89.9%。研究结果表明,醇化烟叶中酵母菌种群数量较小,但酵母菌的生物学特性有利于烟叶醇化,值得进一步深入研究。     

Yeast populations on the tropical timber tree species Milicia excelsa

H. LI, E. VEENENDAAL, N.A. AB SHUKOR, J.R. COBBINAH AND C. LEIFERT. 1995. Yeast populations found on the tropical timber tree species Milicia excelsa showed very little diversity at the genus and species level. Of 62 isolates, 87% were Cryptococcus laurentii , 5% Candida humicola , 3% Candida curvata , 1.5% Candida membranaefaciens , 1.5% Rhodotorula minuta and 1.5% Rhodotorula rubra . Approximately half of the Crypt. laurentii strains had unusual metabolic profiles when compared with the Crypt. laurentii strains in the profile library of the APILAB yeast identification software. All isolated strains were non-pathogenic and did not show antagonism against Botrytis cinerea in an in vitro plate assay. However, three strains of Crypt. laurentii suppressed disease development of B. cinerea in a leaf disk bio-assay. This indicates that protection of leaves against opportunistic fungal diseases may be part of the ecological function of Crypt. laurentii populations on Milicia leaves and the potential of this yeast species for biological control.     

Characterization of three endophytic, indole-3-acetic acid-producing yeasts occurring in Populus trees

Three endophytic yeast, one isolated from stems of wild cottonwood (Populus trichocarpa), two from stems of hybrid poplar (P. trichocarpa × Populus deltoides), were characterized by analyzing three ribosomal genes, the small subunit (18S), internal transcribed spacer (ITS), and D1/D2 region of the large subunit (26S). Phenotypic characteristics of the yeast isolates were also obtained using a commercial yeast identification kit and used for assisting the species identification. The isolate from wild cottonwood was identified to be closest to species Rhodotorula graminis. The two isolates from hybrid poplar were identified to be species Rhodotorula mucilaginosa. In addition, the three yeast isolates were observed to be able to produce indole-3-acetic acid (IAA), a phytohormone which can promote plant growth, when incubated with l-tryptophan. To our knowledge, the yeast strains presented in this study were the first endophytic yeast strains isolated from species of Populus.     

297例浅部真菌病临床及病原菌菌种分析

目的 探讨皮肤浅部真菌病致病真菌菌种的构成.方法 对297例真菌涂片阳性和培养阳性的浅部真菌病患者,取标本进行分离培养及菌种鉴定,培养阳性标本在形态学上不能准确鉴定的,进行梅里埃API 20C AUX酵母菌鉴定试剂盒或核糖体DNA （rDNA） ITS区序列测定,确切鉴定菌种.使用SPSS 17.0统计软件对于结果进行统计分析.结果 共分离培养出致病菌13种,其中红色毛癣菌86株（29.0％）,须癣毛癣菌68株（22.9％）,念珠菌属59株（19.9％）,暗色真菌属13株（4.4％）,曲霉菌属13株（4.4％）,红酵母菌12株（4.0％）,青霉菌属9株（3.0％）,毛霉菌9株（3.0％）,犬小孢子菌5株（1.7％）,浅白隐球菌3株（1.0％）,毛孢子菌属2株（0.7％）,絮状表皮癣菌1株（0.3％）,混合感染17株（5.7％）.结论 本地区浅部真菌病以甲癣为主,主要致病真菌是红色毛癣菌,但其他种类真菌感染尤其是念珠菌属有明显上升趋势.     

Psychrophilic yeasts in glacial environments of Alpine glaciers

The presence of psychrophilic yeasts in supra- and subglacial sediments, ice and meltwater collected from two glaciers of the Italian Alps (Forni and Sforzellina-Ortles-Cevedale group) was investigated. After incubation at 4 degrees C, subglacial sediments contained from 1.3 x 10(3) to 9.6 x 10(3) CFU of yeasts g(-1). The number of yeast cells in supraglacial sediments was c. 10-100-fold lower. A significant proportion of isolated yeasts exhibited one or more extracellular enzymatic activities (starch-degrading, lipolytic, esterolytic, proteolytic and pectinolytic activity) at 4 degrees C. Selected isolates were able to grow at 2 degrees C under laboratory-simulated in situ conditions. In all, 106 isolated yeasts were identified by MSP-PCR fingerprinting and 26S rRNA gene sequencing of the D1/D2 region as belonging to 10 species: Aureobasidium pullulans, Cryptococcus gilvescens (over 50% of the total), Cryptococcus terricolus, Mrakia gelida, Naganishia globosa, Rhodotorula glacialis, Rhodotorula psychrophenolica, Rhodotorula bacarum, Rhodotorula creatinivora and Rhodotorula laryngis. Four strains, all belonging to a new yeast species, yet to be described, were also isolated.     

Dihydroagarofuran alkaloid and triterpenes from Maytenus heterophylla and Maytenus arbutifolia

The antimicrobially active EtOH extracts of Maytenus heterophylla yielded a new dihydroagarofuran alkaloid,1beta-acetoxy-9alpha-benzoyloxy-2beta,6alpha-dinicotinoyloxy-beta-dihydroagarofuran, together with the known compounds beta-amyrin, maytenfolic acid, 3alpha-hydroxy-2-oxofriedelane-20alpha-carboxylic acid, lup-20(29)-ene-1beta,3beta-diol, (-)-4'-methylepigallocatechin, and (-)-epicatechin. In addition, beta-amyrin, (-)-epicatechin and (-)-4'-methylepigallocatechin were isolated from Maytenus arbutifolia. The structure elucidation of the isolated compounds was based primarily on 1D and 2D NMR analyses, including HMQC, HMBC, and NOESY correlations. Maytenfolic acid showed moderate antimicrobial activity by inhibiting the growth of Candida albicans, Cryptococcus neoformans, Staphylococcus aureus and Pseudomonas aeruginosa.     

SAR studies of pyridazinone derivatives as novel glucan synthase inhibitors

A novel series of pyridazinone analogs has been developed as potent β-1,3-glucan synthase inhibitors through structure-activity relationship study of the lead 5-[4-(benzylsulfonyl)piperazin-1-yl]-4-morpholino-2-phenyl-pyridazin-3(2H)-one (1). The effect of changes to the core structure is described in detail. Optimization of the sulfonamide moiety led to the identification of important compounds with much improved systematic exposure while retaining good antifungal activity against the fungal strains Candida glabrata and Candida albicans.     

真菌对石油污染土壤的降解研究

利用微生物对石油污染土壤进行生物降解，具有操作简单，费用低廉，场地适用性强等特点。挑选了2种菌株，进行了室内油降解实验，在摇床实验油降解率：微生物真菌（Faserium．LK）（土著）和真菌（Phanerochaete．Chrysosprium），在20d分别为41.2％和28．1％，真菌（Fusarium．LK）高于真菌（Phane－rochate．Chrysosprium）的降解率，而在培养箱石油污染土壤中，真菌（Fusarium．LK）（土著）和真菌（Phane－rochaete.Chrysosprium），在50d分别为61.8％和66．1％，（Fusarium.LK）低于（Phanerochaete.Chrysosri-um）。