Yeasts as a model for assessing the toxicity of the fungicides Penconazol, Cymoxanil and Dichlofluanid

In the present work the sensitivity of yeast strains of Kluyveromyces marxianus, Pichia anomala, Candida utilis, Schizosaccharomyces pombe and Saccharomyces cerevisiae, to the fungicides cymoxanil, penconazol, and dichlofluanid, was evaluated. Dichlofluanid induced the most negative effects, whereas penconazol in general was not very toxic. Overall, our results show that the parameters IC50 for specific respiration rates of C. utilis and S. cerevisiae and C(D) for cell viability of S. cerevisiae can be applied to quantify the toxicity level of the above compounds in yeast. Hence, could be explored as an alternative or at least as a complementary test in toxicity studies and, therefore, its potential for inclusion in a tier testing toxicity test battery merits further research.     

Pyrene degradation by yeasts and filamentous fungi

The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.     

First evaluation of the Brazilian microorganisms biocatalytic potential

The biocatalytic potential of two novel Brazilian strains of Aspergillus niger and Rhodotorula glutinis, revealed enantioselective epoxide hydrolase activity in the asymmetrization of meso-epoxide and monosubstituted epoxides respectively. These two types of oxirane derivatives are not usually good substrates for biocatalytic enantioselective conversion.     

A comparative study on the biosorption characteristics of some yeasts for Remazol Blue reactive dye

Biosorption capacities and rates of different kinds of dried yeasts (Saccharomyces cerevisiae, Schizosaccharomyces pombe, Kluyveromyces marxianus, Candida sp., C. tropicalis, C. lipolytica, C. utilis, C. quilliermendii and C. membranaefaciens) for Remazol Blue reactive dye from aqueous solutions were compared under laboratory conditions as a function of initial pH and initial dye concentration. Optimum initial biosorption pH was determined as 2 for all the yeasts. All the yeast species showed comparable and very high dye sorption at 100 mg/l initial dye concentration. The equilibrium sorption capacity of the biomass increased with increasing initial dye concentration up to 400 mg/l for Candida sp. C. lipolytica and C. tropicalis; up to 300 mg/l for C. quilliermendii and C. utilis and up to 200 mg/l for S. cerevisiae, S. pombe, K. marxianus and C. membranaefaciens while the adsorption yield of dye showed the opposite trend for all the yeasts. Among the nine yeast species, C. lipolytica exhibited the highest dye uptake capacity (Q(0) = 250 mg/g). Both the Freundlich and Langmuir adsorption models were found suitable for describing the biosorption of the dye by all the Candida yeasts (except C. membranaefaciens). The results indicated that the dye uptake process followed the pseudo-second-order kinetics for each dye-yeast system.     

Biodegradation of phenol and phenol-related compounds by psychrophilic and cold-tolerant alpine yeasts

We characterized 32 cold-adapted, psychrophilic and cold-tolerant, yeast strains isolated from alpine habitats with regard to their taxonomy, growth temperature profile, and ability to degrade phenol and 18 phenol-related mono-aromatic compounds at 10 degrees C. Twenty of the strains were identified by sequencing of the ribosomal ITS region as seven species of the basidiomycota: Cryptococcus terreus (three strains), Cryptococcus terricola (one strain), Rhodosporidium lusitaniae (two strains), Rhodotorula creatinivora (10 strains), Rhodotorula ingeniosa (one strain), Mastigobasidium intermedium (one strain), and Sporobolomyces roseus (two strains). Twelve strains sharing closely related ITS sequences could not be identified to the species level; according to their ITS sequence they are included in the Microbotryomycetidae. These 12 strains were psychrophilic (no growth at temperatures above 20 degrees C); one-third of these strains did not grow above 15 degrees C. None of the 32 strains utilized any of the highly volatile mono-aromatic compounds (benzene, toluene, ethylbenzene, nitrobenzene, o-xylene, m-xylene, and p-xylene) as the sole carbon source. Non/low volatile aromatic compounds were degraded in the following order: phenol>hydroquinone>resorcinol>benzoate>catechol>salicylate>p-cresol>m-cresol. o-Cresol, guaiacol, p-nitrophenol, or p-nitrotoluene were not utilized for growth. R. creatinivora strains degraded up to seven compounds, whereas C. terricola and S. roseus strains degraded only two compounds. The toxicity of the compounds was determined via growth inhibition in the presence of toxicants and nutrients at 10 degrees C. R. creatinivora strains were characterized by higher IC50 values than other species, S. roseus was the most sensitive species. The most toxic compounds were the xylene isomers, ethylbenzene, p-nitrophenol, and m-cresol. There was a relation between the chemical structure of the compounds and their toxicity, whereas a relation between the toxicity of the compounds and the ability of the yeasts strains to utilize these compounds for growth was only detected in some cases.     

Die Wirkung von Cadmium auf Wachstum und Stoffwechsel von Saccharomyces- und Rhodotorula-Zellen

The effect of cadmium chloride on growth and metabolism was tested in Saccharomyces cerevisiae and Rhodotorula rubra.The uptake of cadmium in both yeast strains is the same, but Saccharomyces cells are much more sensitive to cadmium than Rhodotorula cells. In both yeast strains the effect of cadmium on protein synthesis and on transport of glucose or adenine through membranes is very low, the effect on RNA- and ribosome synthesis very high.     

Characterization of isolated yeast growth response to methionine analogs

Methionine is one of the first limiting amino acids in poultry nutrition. The use of methionine-rich natural feed ingredients, such as soybean meal or rapeseed meal may lead to negative environmental consequences. Amino acid supplementation leads to reduced use of protein-rich ingredients. The objectives of this study were isolation of potentially high content methionine-containing yeasts, quantification of methionine content in yeasts and their respective growth response to methionine analogs. Minimal medium was used as the selection medium and the isolation medium of methionine-producing yeasts from yeast collection and environmental samples, respectively. Two yeasts previously collected along with six additional strains isolated from Caucasian kefir grains, air-trapped, cantaloupe, and three soil samples could grow on minimal medium. Only two of the newly isolated strains, K1 and C1, grew in minimal medium supplied with either methionine analogs ethionine or norleucine at 0.5% (w/v). Based on large subunit rRNA sequences, these isolated strains were identified as Pichia udriavzevii/Issatchenkia orientalis. P. kudriavzevii/I. orentalis is a generally recognized as a safe organism. In addition, methionine produced by K1 and C1 yeast hydrolysate yielded 1.3 ± 0.01 and 1.1 ± 0.01 mg g^?1 dry cell. Yeast strain K1 may be suitable as a potential source of methionine for dietary supplements in organic poultry feed but may require growth conditions to further increase their methionine content.     

Influence of fenamidone, indoxacarb, pyraclostrobin, and deltamethrin on the population of natural yeast microflora during winemaking of two sardinian grape cultivars

The influence of fenamidone ((S)-1-anilino-4-methyl-2-methylthio-4-phenylimidazolin-5-one), pyraclostrobin (methyl 2-[1-(4-chlorophenyl)pyrazol-3-yloxymethyl]-N-methoxycarbanilate), indoxacarb (methyl 7-Chloro-2,5-dihydro-2-[[(methoxycarbonyl) [4- (trifluoromethoxy) phenyl] amino] carbonyl] indeno[1,2-e][1,3,4] oxadiazine-4a(3H)-carboxylate), and deltamethrin ([cyano-[3-(phenoxy)phenyl]methyl] 3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane-1-carboxylate) on spontaneous fermentation carried out by natural yeast grapes microflora, was studied during the wine-making process. Aliquots of pesticide standard solutions were added to the grapes before crushing, to reach a concentration equal or half the maximum residue limit (MRL). Vinifications were performed, with maceration (R), or without maceration (W). During the wine-making process, samples were taken at the beginning (one hour after grapes crushing), at the middle and at the end of the spontaneous fermentation process. At half the MRL concentration, deltamethrin affected Pichia sp. population with a decrease of almost 50 %, while fenamidone decreased Candida sp., Candida stellata at 83, and 36%, respectively. Metschnikowia pulcherrima population decreased in all samples when compared to the control. Experiments at MRL levels showed a strong reduction for all non-Saccharomyces yeast species, when grapes had been treated with pyraclostrobin, fenamidone, and deltamethrine, except for Candida sp. which was found to have been affected only by fenamidone residues. Growth zone inhibition test showed only an in vitro activity of pyraclostrobin over Kloeckera spp., C. stellata, and M. pulcherrima. Microvinification experiments produced wines with no differences concerning S. cerevisiae population as well as production of ethanol and residual sugars. Experiments showed that at the end of the fermentation process pesticides were adsorbed by the lees and grape skins, and no pesticides residue was detectable in wine.     

Unterschiedliche Aufnahme von Cadmium in Saccharomyces- BZW. Rhodotorula-Zellen

The uptake of Cadmium-115m in two strains of Saccharomyces and one strain of Rhodotorula cells was measured in the presence and absence of glucose.It was shown that the uptake of cadmium in the absence of glucose is about the same in all three strains.In the presence of glucose one can find an about ten fold higher uptake in Saccharomyces than in Rhodotorula cells.It was concluded from these and other results than cadmium is transported in Rhodotorula cells by diffussion, in Saccharomyces cells by an energy-dependent transport system.These results declare the great difference of the sensitivity of these strains against cadmium and correct a misinterpretation in an earlier publication (1).     

Susceptibility of different yeast species to environmental toxic metals

The purpose of the study reported here was to investigate the relative resistance of yeast species to various metallic and metalloid ions, with a view to gaining more knowledge on this subject, as resistant species may become dominant in habitats contaminated with the relevant metals. Saccharomyces cerevisiae, Candida albicans and Candida tropicalis were grown in media containing different concentrations of mercury (as HgCl(2)), cadmium (as CdCl(2)), lead (as Pb(CH(3)COO)(2)), arsenic (as Na(2)HAsO(4)) and selenium (as Na(2)SeO(3)) for various intervals. Invariably, the two Candida species turned out to be more resistant to all the metals studied than S. cerevisiae. The metal showing the highest toxicity for these species was mercury, with cadmium being the second, lead, the third and arsenic and selenium being the least toxic elements. Strains showing resistance to mercury were isolated, even in the case of S. cerevisiae.     

Bioluminescent yeast assays for detecting estrogenic and androgenic activity in different matrices

In this paper we describe the construction and use of a set of bioluminescent yeast strains for the detection of compounds that can affect androgen or estrogen receptor mediated hormonal signalling. The set includes Saccharomyces cerevisiae strains expressing human androgen receptor (AR), estrogen receptor alpha (ERalpha) or estrogen receptor beta (ERbeta), along with firefly luciferase controlled by a respective hormone responsive promoter. A constitutively luminescent strain was included in the set for determining the cytotoxicity of the sample. Yeast cells were incubated with pure chemicals or complex samples for 2.5 h, after which the signal could be detected from the cell-sample mixture after simply adding the D-luciferin substrate. The assays could be completed in one day and they required no cell lysis or centrifugation steps, which makes them suitable for high-throughput analysis of samples. Due to a short incubation time the assays are directly applicable to different sample matrices, requiring no pretreatment of the samples. The assays were used to assess the hormonal activity in moisturizing lotions as an example of a complex sample matrix known to contain endocrine disrupting chemicals. Six out of eight tested moisturisers showed high estrogenic activity, whereas no androgenic activity was observed in the samples.     

Improvement of soil characteristics and growth of Dorycnium pentaphyllum by amendment with agrowastes and inoculation with AM fungi and/or the yeast Yarowia lipolytica

The effectiveness of two microbiologically treated agrowastes [dry olive cake (DOC) and/or sugar beet (SB)] on plant growth, soil enzymatic activities and other soil characteristics was determined in a natural soil from a desertified area. Dorycnium pentaphyllum, a legume plant adapted to stress situations, was the test plant to evaluate the effect of inoculation of native arbuscular mycorrhizal (AM) fungi and/or Yarowia lipolytica (a dry soil adapted yeast) on amended and non-amended soils. Plant growth and nutrition, symbiotic developments and soil enzymatic activities were limited in non-amended soil where microbial inoculations did not improve plant development. The lack of nodules formation and AM colonization can explain the limited plant growth in this natural soil. The effectiveness and performance of inocula applied was only evident in amended soils. AM colonization and spores number in natural soil were increased by amendments and the inoculation with Y. lipolytica promoted this value. The effect of the inoculations on plant N-acquisition was only important in AM-inoculated plants growing in SB medium. Enzymatic activities as urease and protease activities were particularly increased in DOC amended soil meanwhile dehydrogenase activity was greatest in treatments inoculated with Y. lipolytica in SB added soil. The biological activities in rhizosphere of agrowaste amended soil, used as indices of changes in soil properties and fertility, were affected not only by the nature of amendments but also by the inoculant applied. All these results show that the lignocellulosic agrowastes treated with a selected microorganism and its further interaction with beneficial microbial groups (native AM fungi and/or Y. lipolytica) is a useful tool to modify soil physico-chemical, biological and fertility properties that enhance the plant performance probably by making nutrients more available to plants.     

Temporal and spatial variation of arsenic species in the Dahuofang reservoir in northeast China

Overlying water, pore water, and sediment samples were collected from the Dahuofang reservoir in November 2011 and April 2012, respectively. Total arsenic and arsenic species including arsenite, arsenate, monomethylarsonic, and dimethylarsinic were analyzed by ICP-MS and HPLC–ICP-MS. The results indicated that the environments of the Dahuofang reservoir were in reduced conditions, arsenite was the predominant species in pore water and sediments in the reservoir. Arsenic concentrations in overlying water were very low in all the samples but showed different trend during the different time. In November, arsenic concentrations in the reservoir inlet were higher than that in the other sites, whereas arsenic showed accumulation from the upstream to downstream of the reservoir in samples collected in April. In pore water, arsenic concentrations were about 23 and 37 times higher than those in overlying water in November and April, respectively, and relatively high levels of arsenite were also detected in the pore water. In surface sediments, total arsenic and arsenic species content in the reservoir inlet showed the following decreasing order: R1?>?R10?>?R4. The results also showed that moderate ecological risks exist in pore water and sediments in the Dahuofang reservoir.     

Essential interactions between Thiobacillus ferrooxidans and heterotrophic microorganisms during a wastewater sludge bioleaching process

The stimulating effect of heterotrophic microorganisms was investigated on the growth and on the ferrous iron oxidation of Thiobacillus ferrooxidans in synthetic media and in wastewater sludge. The addition of a sediment. Rhodotorula rubra isolate or a strain of T. acidophilus on two-layer agarose-gelled medium doubled the plating efficiency of T. ferrooxidans. In liquid cultures, R. rubra had a slight but significant effect on the growth rate of T. ferrooxidans. Moreover, the yeast allowed a faster initiation of the ferrous iron oxidation and acidification by T. ferrooxidans. In the bioleaching process, the co-culture of T. ferrooxidans with R. rubra or with the indigenous microbial assemblage from sludge was shown to be essential since the pure culture of T. ferrooxidans failed to oxidize ferrous iron and to acidify wastewater sludge. These results emphasize the importance of active heterotrophic microorganisms in the metal bioleaching activity of T. ferrooxidans in sludge.     

Influence of Spartina alterniflora on the mobility of heavy metals in salt marsh sediments of the Yangtze River Estuary, China

Using bio-disturbed sulphide to trace the mobility and transformation of Cu, Pb, Ni and Zn in the sediments of the Spartina alterniflora-dominated salt marsh in the Yangtze River Estuary, measurements were made of the seasonal variations of acid-volatile sulphide (AVS) and of the simultaneously extracted metals (SEM) in the rhizosphere sediments. Microcosm incubation experiments recreating flooding conditions were conducted to evaluate the effect of AVS and other metal binding phases upon the dynamics of Cu, Pb, Ni and Zn in the salt marsh sediments. The results demonstrate that the ratio values of SEM/AVS have a significant seasonal variation in the rhizosphere sediments and that the anoxic conditions in the sediments were likely enhanced by S. alterniflora during the summer and autumn compared with the anoxic conditions resulting from the native species Phragmites australis and Scirpus mariqueter. The incubation experiments suggest that Fe(III) and Mn(IV/III) (hydr)oxides provide important binding sites for heavy metals under oxic conditions, and sulphide provides important binding sites for the Cu and Pb under anoxic conditions. Our observations indicate that the mobility of heavy metals in the salt marsh sediments is strongly influenced by biogeochemical redox processes and that the invasive S. alterniflora may increase the seasonal fluctuation in heavy metal bioavailability in the salt marsh ecosystem.     

Reductive dechlorination of polychlorinated biphenyls as affected by sediment characteristics

The effect of sediment sources on the selection of polychlorinated biphenyl (PCB) dechlorinating competence was investigated using sediments from two different locations, the Grasse River and Owasco Lake. These two sediments had a similar organic carbon content but different particle size distribution. The two PCB-free sediments were spiked with Aroclor 1248 and inoculated with microorganisms from the Reynolds and General Motors sites in the St. Lawrence River, which exhibited different dechlorination patterns. When each inoculum was serially transferred into fresh sediments four times (every 8-10 weeks), they still maintained the initial dechlorination patterns regardless, the source of sediments and the number of transfers, and dechlorination patterns of the two inocula in the same sediments did not converge. In a parallel approach, when the acclimated microorganisms from the Reynolds site were inoculated into fresh sediments from both sources as well as sediments enriched with organic carbon (2%, w/v), the dechlorination pattern remained unchanged after a 40-week incubation. These results suggest that the sediment characteristics or organic carbon content did not play a role in the selection of dechlorinating populations.     

三菌复合发酵提高厨余真蛋白含量的研究

为改善厨余发酵的品质,增加发酵后产品蛋白含量。采用三菌复合对厨余进行发酵,探讨了三菌复合的比例、接种量、发酵时间、初始pH值对发酵效果的影响,采用L9(34)正交实验对发酵条件进行优化,并对实验菌Lc和Ydy进行16S rRNA及18S rRNA分子鉴定。结果表明,最佳发酵条件为:菌剂配比(Lc∶Ydy∶S1)为3∶2∶1,接种量为0.15%,初始pH值为5.0,发酵时间为48 h。扩大实验结果表明,在最优发酵条件下,厨余经发酵后品质得到改善,真蛋白含量由发酵前的15.42%上升到发酵后的22.47%,增加率为45.80%;发酵后大肠菌群下降到30 cfu/g以下;乳酸菌及酵母菌数量分别为1.5×109 cfu/g和6.6×108 cfu/g。分子测序及鉴定结果表明,Lc为乳酸乳球菌,Ydy为热带假丝酵母菌。     

Degradation of inhibitory substances by heterotrophic microorganisms during bioleaching of heavy metals from anaerobically digested sewage sludge

The presence of organic acids was found to be inhibitory to the bioleaching of sewage sludge and the objective of the present study was to elucidate the roles of heterotrophic microorganisms in removing organic acids during the bioleaching of heavy metals from anaerobically digested sewage sludge. Microbiological analysis showed that acetic and propionic acids posed a severe inhibitory effect on iron-oxidizing bacteria as reflected by a sharp decrease in their viable counts in the first 4d and it only started to increase 2d after the depletion of both acids. Biodegradation of these inhibitory organic acids was revealed by sharp increases in total fungi and acidophiles between day 3 and day 5 which coincided with degradation of organic acids. This was further confirmed by the increases in total counts of both acetate and propionate degraders in the same period. Two yeast strains Y4 and Y5 with strong ability to degrade acetate and/or propionate were isolated and identified as Pichia sp. and Blastoschizomycetes capitatus, respectively. B. capitatus Y5 was an more important player in removing the inhibitory organic acids during the bioleaching process since it could utilize both acetate and propionate as sole carbon source while Pichia sp. Y4 was an strict acetate degrader. Results from the present study not only provided the evidence for biodegradation of organic acids by heterotrophs, but also disclosed a biological mechanism for the initiation of bioleaching of organic acid-laden sewage sludge.     

Strategies of heavy metal uptake by three plant species growing near a metal smelter

Some higher plant species have developed heavy metal tolerance strategies which enable them to survive and reproduce in highly metal-contaminated soils. We have investigated such heavy metal uptake and accumulation strategies of two absolute metallophyte species (Armeria maritima ssp. halleri and Cardaminopsis halleri) and one pseudometallophyte (Agrostis tenuis) growing near a former metal smelter. Samples of plant parts and soil were analysed for Zn, Cd, Pb, and Cu. In soil, there were two dominant types of metal concentration gradients with depth. Under the absolute metallophytes, extremely high metal contents were measured in the surficial Ah horizon, followed by a strong decrease in the underlying soil horizons (L(11) and L(12)). Under the pseudometallophyte, metal concentrations in the Ah horizon were much lower and fewer differences were observed in metal concentrations among the Ah, L(11), and L(12) horizons. The concentrations of Zn, Cd, Pb, and Cu in Agrostis tenuis roots were greater than concentrations in leaves, indicating significant metal immobilisation by the roots. For C. halleri, Zn and Cd concentrations in leaves were >20,000 and >100 mg kg(-1), respectively, indicating hyperaccumulation of these elements. Armeria maritima ssp. halleri exhibited root concentrations of Pb and Cu that were 20 and 88 times greater, respectively, than those in green leaves, suggesting an exclusion strategy by metal immobilisation in roots. However, Zn, Cd, Pb, and Cu concentrations in brown leaves of Armeria maritima ssp. halleri were 3-8 times greater than in green leaves, suggesting a second strategy, i.e. detoxification mechanism by leaf fall.     

河道沉积物中磷的分布、吸附及释放规律研究

为科学评价磷在河道沉积物中的环境行为,在模拟条件下研究了上海市进木港和苏州河沉积物中磷的分布形态、吸附特征及释放规律.结果表明:(1)2种沉积物中碎屑钙磷(De-P)浓度最高,闭蓄态磷(Oc-P)次之,其他形态磷浓度相对较低,而活性磷中以铁磷(Fe-P)为主;(2)2种沉积物对磷的吸附均符合线性方程,在4.0h时基本达...