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Streptomyces species are prolific producers of bioactive metabolites, such as (3-lactone-containing lipstatin produced by Streptomyces toxytricini, an intermediate used in semi-synthetic process for production of anti-obesity drug orlistat. Understanding the distribution of identical or structurally similar molecules produced by a taxonomic group is of particular importance when trying to isolate novel biologically active compounds or strains producing known metabolites of medical importance with potentially improved properties. Until now, only two independent isolates of S. toxytricini species have been known to be producers of lipstatin. According to the current taxonomic criteria, S. toxytricini belongs to Streptomyces lavendulae phenotypic cluster. Taxonomy-based dereplication approach coupled with in vitro assay was applied to screen the S. lavendulae phenotypic cluster for production of lipstatin-like lipase inhibitors using synthetic p-nitrophenol derivatives of C4 and Ci6 lipids. Screening the available strains from public collections belonging to S. lavendulae phenotypic cluster, high lipase inhibitory activity was identified in the Streptomyces virginiae CBS 314.55 culture supernatants. HPLC and LC-MS/MS confirmed lipstatin production by a new Streptomyces species for the first time. We have demonstrated that the new lipstatin-producing strain S. virginiae morphologically and physiologically differs from S. toxytricini substantially; however, the production capacity of the newly identified lipstatin-producing species S. virginiae is comparable to S. toxytricini. We have thus demonstrated the effectiveness of a simple and affordable dereplication approach for identification of potentially novel and useful industrial strains available in public culture collections. [ABSTRACT FROM AUTHOR]

The interaction between four industrial wine yeast strains and grape juice chemical contaminants during alcoholic fermentation was studied. Industrial strains of Saccharomyces cerevisiae (AWRI 0838), S. cerevisiae mutant with low H2S production phenotype (AWRI 1640), interspecies hybrid of S. cerevisiae and S. kudriavzevii (AWRI 1539) and a hybrid of AWRI 1640 and AWRI 1539 (AWRI 1810) were exposed separately to fungicides pyrimethanil (Pyr, 10 mg/L) and fenhexamid (Fhx, 10 mg/L), as well as to the most common toxin produced by moulds on grapes, ochratoxin A (OTA, 5 mg/L), during alcoholic fermentation of Vitis vinifera L. cv. Sauvignon blanc juice. Contaminants were found to strongly impair fermentation performance and metabolic activity of all yeast strains studied. The chemical profile of wine was analyzed by HPLC (volatile acidity, concentrations of ethanol, fructose, glucose, glycerol and organic acids) and the aromatic profile was analyzed using a stable isotope dilution technique using GC/MS (ethyl esters, acetates and aromatic alcohols) and Kitagawa tubes (H2S). The chemical composition of wine with added contaminants was in all cases significantly different from the control. Of particular note is that the quantity of aromatic compounds produced by yeast was significantly lower. Yeast's capacity to remove contaminants from wine at the end of the alcoholic fermentation, and after extended contact (7 days) was determined. All the strains were able to remove contaminants from the media, moreover, after extended contact, the concentration of contaminants was in most cases lower. [ABSTRACT FROM AUTHOR]

The paper examines the impact of ethanol, and hidroxycinnamic and vinylphenol precursors on the production of volatile phenols in fermentations of mixed and pure cultures of yeasts Saccharomyces cerevisiae and Dekkera bruxellensis. Three different D. bruxellensis strains were examined and they all showed a unique volatile phenol production pattern in the fermentations of pure and mixed cultures. Generally, the results showed that in mixed culture fermentations less vinylphenols and more ethylphenols were produced in comparison with D. bruxellensis pure culture fermentations. Vinylphenol precursors significantly inhibited the growth of S. cerevisiae and the production of ethylphenols. Nevertheless, it was found that D. bruxellensis genes encoding for enzymes coumaric acid decarboxylase (CAD) and vinylphenol reductase (VPR) are more responsive to vinylphenol precursors in comparison with hidroxycinnamic acids. Consequently, higher concentrations of vinylphenols in the cell were found to be more cytotoxic than hidroxycinnamic acids. In general, low ethanol concentrations induced higher production of volatile phenols by S. cerevisiae and D. bruxellensis. This was confirmed with the expression pattern of gene encoding for CAD of D. bruxellensis. [ABSTRACT FROM AUTHOR]

Lipid content in food strongly influences food perception on the level of textural properties. Lipids in contact with the tongue and palate are substantially responsible for the sensory impact of a product. The aim of this study is to investigate the impact of oil content on the thickness of lipid deposition on oral surface as well as on the mouthfeel perception. The fluorescent probe method was used to study the thickness of lipid deposition on oral surface. We observed an increase in the thickness of lipid deposition depending on the increase of oil content in oil/water dispersions. Clear correlation was shown between the thickness of lipid deposition on oral surfaces and the perception of mouthfeel. A direct measure of undisrupted deposition of food components on oral surface contributes to the understanding of the behaviour of food components in the mouth and their influence on mouthfeel perception. [ABSTRACT FROM AUTHOR]

Bee products such as royal jelly, honey and propolis have been reported to possess several biological activities. In order to better understand their mechanism of action and, consequently, their efficiency and safety, 'omic' approaches are used. Here cases with proteomic approach are indicated. In addition to studying biological activity at a proteome level, a proteomic approach for investigation of bee products has also been applied in analyzing proteins as their (bioactive) components. [ABSTRACT FROM AUTHOR]

Impact of three fungicides against B. cinerea (iprodione, pyrimethanil and fludioxonil plus cyprodinil) on the population of Saccharomyces cerevisiae strains during the spontaneous alcoholic fermentation was studied. With regard to the use of fungicides in the vineyard at two stages of the grapevine growth we followed four different spontaneous fermentations: control, iprodione, pyrimethanil and fludioxonil plus cyprodinil. The fungicide residues in the grapes were determined by GC/MS system and the fermentations were followed by changes in yeast, sugar, and ethanol concentrations using colony counting and HPLC. The karyotype analysis of 473 isolates was done by pulsed-field gel electrophoresis. The fungicide residues in the grapes at the harvest were below the maximum residue limits. Isolates of S. cerevisiae were classified into 15 karyotype groups. The duration of the processes and the populations of the karyotypes differed between the fermentations. The iprodione and control fermentations lasted 36 days with the prevalence of karyotype A while the fludioxonil plus cyprodinil fermentation lasted 50 days and karyotype D led the process. In the pyrimethanil fermentation, none of the karyotypes prevailed in the must and the fermentation lasted much longer than others did (68 days). The results showed that the fungicide residues have an influence on the fermentation kinetics and selection of S. cerevisiae strains during the spontaneous alcoholic fermentation and therefore should be considered as an important factor that may indirectly influence the formation of fermentation aroma in the wine produced by such process. [ABSTRACT FROM AUTHOR]

The abc1/ coq8 gene deletion respiratory-deficient mutant NBp17 of fission yeast Schizosaccharomyces pombe displayed a phenotypic fermentation pattern with enhanced production of glycerol and acetate, and also possessed oxidative stress-sensitive phenotypes to HO, menadione, tBuOOH, Cd, and chromate in comparison with its parental respiratory-competent strain HNT. As a consequence of internal stress-inducing mutation, adaptation processes to restore the redox homeostasis of mutant NBp17 cells were detected in minimal glucose medium. Mutant NBp17 produced significantly increased amounts of O and HO as a result of the decreased internal glutathione concentration and the only slightly increased glutathione reductase activity. The Cr(VI) reduction capacity and hence the OH production ability were decreased. The mutant cells demonstrated increased specific activities of superoxide dismutases and glutathione reductase (but not catalase) to detoxify at least partially the overproduction of reactive oxygen species. All these features may be explained by the decreased redox capacity of the mutant cells. Most notably, mutant NBp17 hyperaccumulated yellow CdS. [ABSTRACT FROM AUTHOR]

An investigation into the antifungal activities of anti-microbially, hydrophobically and oleophobically finished cotton fabrics designed for tents and marquees was performed according to the AATCC 30-1999 (IV) test method. The growth of test moulds (Aspergillus niger, Penicilium pinophilum and Trichoderma harzianum) on differently treated cotton fabric samples was evaluated according to the standard procedure and additionally using image processing and analysis, which have, to a great extent, increased the accuracy of standard organoleptic estimation. Image processing and analysis enabled an exact evaluation of tests of microorganism growth over a percentage area of a fabric sample covered by fungi, after a defined exposure period. The introduction of an evaluation technique using image processing and analysis was shown to be suitable for the purpose of assessing fungal attack. The results of the tests performed on selected antifungal compounds showed significant distinctions even between those cotton fabric samples treated with different amounts of antifungal agents. [ABSTRACT FROM AUTHOR]

Proteins from the extracellular medium of Aeropyrum pernix K1 were separated by two-dimensional electrophoresis and identified using mass spectrometry. Six different substrate-binding proteins (SBPs) from the ATP-binding cassette (ABC) transporter family were identified: (1) ABC transporter SBP (Q9YC61); (2) Branched-chain amino-acid ABC transporter, branched-chain amino-acid-binding protein (Q9YDJ6); (3) Oligopeptide ABC transporter, oligopeptide-binding protein (Q9YBL5); (4) Probable ABC transporter SBP (Q9Y9N4); (5) ABC transporter SBP (Q9YBG7); (6) ABC transporter SBP (Q9YFD7). Based on their orthology, division into the following classes was predicted: (1) multiple sugar-transport system SBPs; (2) peptide/nickel-transport system SBPs; and (3) branched-chain amino-acid-transport system SBPs. Further bioinformatic analyses showed that the identified SBPs differ in motif and in transmembrane-domain and signal-peptide organisation. Additionally, for all of these SBPs, sequence homology was found for archaeal proteins, and homologous proteins in bacteria were also found for the ABC transporter SBP Q9YBG7 and the ABC transporter SBP Q9YFD7. This is the first study, where different ABC SBPs from the extracellular medium of A. pernix have been identified using the combined methodology of two-dimensional electrophoresis and mass spectrometry. [ABSTRACT FROM AUTHOR]

The objective of the research is to determine the leading microorganisms in spontaneous fermentations of table olives in Slovenian Istria. The influence of traditional regional and modified Spanish style technology on yeast and lactic acid bacteria population dynamics and on the quality of Istrska belica and Storta table olive varieties was studied during 180 days of fermentation. Apart from that, pH of the brine during fermentation and total biophenols in olive fruits before processing and after 60 and 180 days of fermentation were determined. The quality of the final product was determined with sensory analysis. Table olive fermentation was carried out by yeasts. Aureobasidium pullulans, Cryptococcus adeliensis, Metschnikowia pulcherrima, Rhodotorula mucilaginosa, Pichia anomala and Candida oleophila were isolated and identified using PCR-RFLP analysis of ITS regions and traditional phenotypic tests. High initial amount of total biophenols in olive fruits and their better preservation during traditional processing influenced microbial population dynamics and quality characteristics of table olives. The modified Spanish style technology was not confirmed as suitable for retaining positive characteristics of the product of traditional regional technology in Slovenian Istria. [ABSTRACT FROM AUTHOR]

Biocontrol activities of different yeast species and strains isolated from grape/must/ wine environments have been compared to those of commercially available antagonistic yeast species of Candida oleophila. A total of 591 yeast isolates were tested in a preliminary screening on agar to select isolates showing inhibitory effect against Botrytis cinerea, the plant pathogen causing grey mould disease on grape. Yeast species Aureobasidium pullulans, Metschnikowia pulcherrima and Pichia guilliermondii showed, on average, higher biocontrol activity than commercially used yeast Candida oleophila. Furthermore, these three species and Saccharomyces cerevisiae, which is potentially interesting biocontrol agent against grey mould of grapes, were selected for their inhibitory effects and assayed in vitro on different solid synthetic media for their antagonistic capacity towards B. cinerea. The results indicate that the composition of the medium had an impact on the biocontrol activity of yeast species and strains, as Saccharomyces cerevisiae showed the highest antagonistic activity against B. cinerea when tested on media with increased concentrations of glucose. The antagonistic activitv of selected yeast strains was finally determined on wounded and sound grape berries of cultivars Rebula and Chardonnay for their ability to inhibit infection by B. cinerea moulds. Results suggest that antagonist yeasts with the potential to control B. cinerea on grape can be found among the microflora associated with the berries. [ABSTRACT FROM AUTHOR]

In this contribution, the influence of various physicochemical factors on Saccharomyces cerevisiae invasive growth is examined quantitatively. Agar-invasion assays are generally applied for in vitro studies on S. cerevisiae invasiveness, the phenomenon observed as a putative virulence trait in this clinically more and more concerning yeast. However, qualitative agar-invasion assays, used until now, strongly limit the feasibility and interpretation of analyses and therefore needed to be improved. Besides, knowledge in this field concerning the physiology of invasive growth, influenced by stress conditions related to the human alimentary tract and food, is poor and should be expanded. For this purpose, a quantitative agar-invasion assay, presented in our previous work, was applied in this contribution to clarify the significance of the stress factors controlling the adhesion and invasion of the yeast in greater detail. Ten virulent and non-virulent S. cerevisiae strains were assayed at various temperatures, pH values, nutrient starvation, modified atmosphere, and different concentrations of NaCl, CaCl2 and preservatives. With the use of specific parameters, like a relative invasion, eight invasive growth models were hypothesized, which enabled intelligible interpretation of the results. A strong preference for invasive growth (meaning high relative invasion) was observed when the strains were grown on nitrogen- and glucose-depleted media. A significant increase in the invasion of the strains was also determined at temperatures typical for human fever (37-39 °C). On the other hand, a strong repressive effect on invasion was found in the presence of salts, anoxia and some preservatives. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The essential general features required for lipid membranes of extremophilic archaea to fulfill biological functions are that they are in the liquid crystalline phase and have extremely low permeability of solutes that is much less temperature sensitive due to a lack of lipid-phase transition and highly branched isoprenoid chains. Many accumulated data indicate that the organism’s response to extremely low pH is the opposite of that to high temperature. The high temperature adaptation does not require the tetraether lipids, while the adaptation of thermophiles to acidic environment requires the tetraether polar lipids. The presence of cyclopentane rings and the role of polar heads are not so straightforward regarding the correlations between fluidity and permeability of the lipid membrane. Due to the unique lipid structures and properties of archaeal lipids, they are a valuable resource in the development of novel biotechnological processes. This microreview focuses primarily on structural and physicochemical properties of polar lipids of (hyper)thermophilic archaea. [ABSTRACT FROM AUTHOR]

The expression of bacterial polyketide synthase gene clusters is often controlled by a number of different families of regulatory proteins that can have either a pathway-specific or a pleiotropic mode of action, e.g. the SARP family (Streptomyces antibiotic regulatory proteins), ribosome-associated ppGpp synthetase, γ-butyrolactone-binding regulatory proteins, and two-component regulatory proteins. The molecular genetics of such regulatory mechanisms that govern the biosynthesis of tetracyclines is poorly understood. In this work, a comparative bioinformatic analysis of regulatory genes present in three tetracycline antibiotic gene clusters, namely oxytetracycline (OTC), chlortetracycline and recently cloned chelocardin gene clusters of S. rimosus, S. aureofaciens and Amycolatopsis sulphurea has been performed. A SARP family regulatory protein is located in the chlortetracycline gene cluster, but is not detected in the gene cluster encoding OTC biosynthesis. Interestingly, the only regulatory element identified in chelocardin gene cluster was chdA, an otrR and ctcR homologue from the TetR family of regulators that regulates the expression of the otrB and ctc05 exporter genes in the oxytetracycline and chlortetracycline gene clusters. In the oxytetracycline gene cluster, a new LAL (LuxR) family regulatory gene homologue, otcG, was identified. This homologue is also present in the ctc gene cluster. By gene disruption and overexpression experiments, a 'conditionally positive' role of otcG in OTC biosynthesis has been demonstrated. The observation, the bioinformatics data and the previous work on phosphate regulation suggest the presence of a more complex, fine tuning role of the otcG gene product in overall expression of genes for OTC biosynthesis. [ABSTRACT FROM AUTHOR]

Selenium is an essential microelement in human and animal nutrition, whose intake can be in inorganic (e.g. selenite, selenate) or organic form (e.g. selenomethionine). The prooxidant effect of inorganic selenium sources in the animal nutrition has been found as a great disadvantage. Therefore, in this study the effect of the ATP sulphurylase on the prooxidant properties and toxicity of selenate in the fission yeast model organism Schizosaccharomyces pombe has been studied. Two strains of yeast Schizosaccharomyces pombe were used, selenate resistant (SeR) ZIM 1889 and selenate sensitive (SeS) ZIM 1878 strains, with inactive and active ATP sulphurylase, respectively. During the yeasts' exposure to selenate growth, intracellular oxidation, cell viability and antioxidative defence systems were determined. Also, activities of antioxidative enzymes (catalase, superoxide dismutases, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase) and intracellular content of reduced glutathione were measured. The results show altered enzymatic activities and decreased intracellular content of reduced form of glutathione in the selenate sensitive strain as a consequence of active ATP sulphurylase, which enables selenate reduction leading to oxidative stress. During the selenate reduction, reactive oxygen species (ROS) are generated and therefore antioxidative defence systems are induced. In contrast, in the selenate resistant strain with inactive ATP sulphurylase, where selenate reduction does not occur, no induction of antioxidative defence systems was found. Consequently, the active ATP sulphurylase is the key enzyme for the prooxidant properties of selenate and it seems to be the main reason for selenate toxicity and ROS formation during the selenate reduction. [ABSTRACT FROM AUTHOR]