Levels of protein carbonylation in peach fruits inoculated with four antagonistic yeasts (
Pichia membranaefaciens,
Cryptococcus laurentii,
Candida guilliermondii and
Rhodotorula glutinis) were ...significantly reduced in response to reactive oxygen species (ROS) caused by
Monilinia fructicola. In control fruit without yeast treatments, proteins carbonylation obviously increased after inoculation with
M. fructicola, ranging from molecular mass 20 to 120 kDa. However, in yeast-treated fruits, no proteins carbonylation was detected at 1 d, only a small quantity of carbonylation ranging from 28.5 to 45 kDa was found at 2 d. Antagonistic yeasts significantly stimulated the activities of chitinase, β-1,3-glucanase, catalase (CAT), peroxidase (POD) and the expressions of relevant genes during all storage periods. These results suggest that yeast treatments may be related to alleviating proteins carbonylation and mitigating pathogen-induced oxidative damage, which result in decrease of fruit decay and imply that antioxidant defense response may be involved in the mechanisms of microbial biocontrol agents against fungal pathogen.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The aim of this study was to know the yeast biodiversity from fresh olive (
Olea europaea L.) fruits, olive paste (crush olives) and olive pomace (solid waste) from Arbequina and Cornicabra ...varieties. Yeasts were isolated from fruits randomly harvested at various olive groves in the region of Castilla La Mancha (Spain). Olive paste and pomace, a byproduct of the processing of this raw material, were also collected in sterile flasks from different oil mills. Molecular identification methodology used included comparison of polymerase chain reaction (PCR) amplicons of their 5.8S rRNA gene and internal transcribed spacers ITS1 and ITS2 followed by restriction pattern analysis (RFLP). For some species, sequence analysis of the 5.8S rDNA gene was necessary. The results were compared to sequences held in public databases (BLAST). These techniques allowed to identify fourteen different species of yeasts, belonging to seven different genera (
Zygosaccharomyces,
Pichia,
Lachancea,
Kluyveromyces,
Saccharomyces,
Candida,
Torulaspora) from the 108 yeast isolates. Species diversity was thus considerable:
Pichia caribbica,
Zygosaccharomyces fermentati (
Lachancea fermentati) and
Pichia holstii (
Nakazawaea holstii) were the most commonly isolated species, followed by
Pichia mississippiensis,
Lachancea sp.,
Kluyveromyces thermotolerans and
Saccharomyces rosinii. The biotechnological properties of these isolates, was also studied. For this purpose, the activity of various enzymes (β-glucosidase, β-glucanase, carboxymethylcellulase, polygalacturonase, peroxidase and lipase) was evaluated. It was important that none of species showed lipase activity, a few had cellulase and polygalacturonase activities and the majority of them presented β-glucanase, β-glucosidase and peroxidase activities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the present study, natural antimicrobials chitosan and thyme, and their combination, were evaluated for their effect on the shelf life of a ready-to-cook (RTC) chicken-pepper kebab (skewer) stored ...under modified atmosphere packaging (MAP) conditions at 4 +/- 0.5 degrees C for 14 days. The following treatments were examined: control samples stored under aerobic packaging (A), samples stored under MAP (M), samples treated with 1.5% chitosan (vol/wt) and stored under MAP (M-CH), samples treated with 0.2% thyme essential oil (vol/wt) (M-T), and samples treated with 1.5% chitosan (vol/wt) and 0.2% thyme essential oil (vol/wt) and stored under MAP (M-CH-T). Treatment M-CH-T significantly affected aerobic plate counts and counts of lactic acid bacteria, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae, and yeasts and molds during the entire storage period. Similarly, lipid oxidation of the RTC product was retarded (M-CH-T treatment) during storage, whereas redness was maintained in M-T, M-CH, and M-CH-T samples. Based primarily on sensory data (taste attribute), M-CH and M-T treatments extended RTC product shelf life by 6 days, whereas M-CH-T treatment resulted in a product with a shelf life of 14 days that maintained acceptable sensory characteristics (shelf life of the control was 6 days).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The purpose of introns in the architecturally simple genome of Saccharomyces cerevisiae is not well understood. To assay the functional relevance of introns, a series of computational analyses and ...several detailed deletion studies were completed on the intronic genes of S. cerevisiae. Mining existing data from genomewide studies on yeast revealed that intron-containing genes produce more RNA and more protein and are more likely to be haplo-insufficient than nonintronic genes. These observations for all intronic genes held true for distinct subsets of genes including ribosomal, nonribosomal, duplicated, and nonduplicated. Corroborating the result of computational analyses, deletion of introns from three essential genes decreased cellular RNA levels and caused measurable growth defects. These data provide evidence that introns improve transcriptional and translational yield and are required for competitive growth of yeast.
Our aim was to investigate the response of selected yeasts and yeast-like fungi from extreme environments to various temperatures at the level of their plasma membranes, in order to elucidate the ...connections between their plasma-membrane fluidity (measured by electron paramagnetic resonance spectroscopy – EPR), growth temperature range, stress tolerance, and ecological distribution. Although all studied fungi can be considered mesophilic according to their growth temperature profiles, their plasma-membrane fluidity indicated otherwise. Arctic yeast
Rhodosporidium diobovatum could be classified as psychrotolerant due to its higher average membrane fluidity. Extremely halotolerant black yeast-like fungus
Hortaea werneckii isolated from solar salterns, on the other hand, is not adapted to low temperature, which is reflected in the higher average rigidity of its plasma membrane and as a consequence its inability to grow at temperatures lower than 10
°C. The plasma membrane of
Aureobasidium sp. isolated so far exclusively from an Arctic glacier with its intermediate fluidity and high fluidity variation at different temperatures may indicate the specialization of this yeast-like fungus to the specific glacial environment. Similar behaviour of plasma membrane was detected in the reference yeast, non-extremophilic
Saccharomyces cerevisiae. Its membranes of intermediate fluidity and with high fluidity fluctuation at different temperatures may reflect the specialization of this yeast to mesophilic environments and prevent its colonization of extreme environments. Halotolerant
Aureobasidium pullulans from salterns, and Arctic
Cryptococcus liquefaciens and
Rhodotorula mucilaginosa with moderately fluctuating plasma membranes of intermediate fluidity are representatives of globally distributed generalistic and stress-tolerant species that can thrive in a variety of environments. Keeping the membranes stable and flexible is one of the necessities for the microorganisms to survive changes in extreme habitats. Our data suggest that plasma-membrane fluidity can be used as an indicator of fitness for survival in the extreme environments. In addition to the average fluidity of plasma membrane, the fluctuation of fluidity is an important determinant of stress tolerance: high absolute fluidity fluctuation is tied to decreased survival. The fluidity and its variation therefore reflect survival strategy and fitness in extreme environments and are good indicators of the adaptability of microorganisms.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Gaseous chlorine dioxide (ClO2) was tested for its effectiveness in killing Salmonella, yeasts, and molds on blueberries, strawberries, and red raspberries. An inoculum (100 microliter, 6.0 to 6.8 ...log CFU/g of fruit) that contained five serotypes of Salmonella enterica was deposited on the skin, calyx tissue, or stem scar tissue of blueberries, skin or stem scar tissue of strawberries, and skin of red raspberries, dried for 2 h at 22 degrees C, then held for 20 h at 4 degrees C and 2 h at 22 degrees C before treatment. Sachets that contained reactant chemicals were formulated to release gaseous ClO2 at concentrations of 4.1, 6.2, and 8.0 mg/liter of air within treatment times of 30, 60, and 120 min, respectively, at 23 +/- 1 degrees C. Lethality of ClO2 to Salmonella, yeasts, and molds was measured when fruits were in an atmosphere that contained 75 to 90% relative humidity. Treatment with 8.0 mg/liter of ClO2 significantly (alpha = 0.05) reduced the population of Salmonella on blueberries by 2.4 to 3.7 log CFU/g. Lethality was higher to cells in inoculum placed on the skin compared with the stem scar tissue. Populations of Salmonella on strawberries treated with 8.0 mg/liter of ClO2 were reduced by 3.8 to 4.4 log CFU/g; a significant reduction of 1.5 log CFU/g of raspberries was achieved. Treatment with 4.1 to 8.0 mg/liter of ClO2 caused reductions in populations of yeast and molds on blueberries, strawberries, and raspberries of 1.4 to 2.5, 1.4 to 4.2, and 2.6 to 3.0 log CFU/g, respectively. Treatment with 4.1 mg/liter of ClO2 did not markedly affect the sensory quality of fruits stored for up to 10 days at 8 degrees C. Results indicate that gaseous ClO2 has promise as a sanitizer for small fruits.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The last four years have brought exciting progress in membrane protein research. Finally those many efforts that have been put into expression of eukaryotic membrane proteins are coming to fruition ...and enable to solve an ever-growing number of high resolution structures. In the past, many skilful optimization steps were required to achieve sufficient expression of functional membrane proteins. Optimization was performed individually for every membrane protein, but provided insight about commonly encountered bottlenecks and, more importantly, general guidelines how to alleviate cellular limitations during microbial membrane protein expression. Lately, system-wide analyses are emerging as powerful means to decipher cellular bottlenecks during heterologous protein production and their use in microbial membrane protein expression has grown in popularity during the past months.This review covers the most prominent solutions and pitfalls in expression of eukaryotic membrane proteins using microbial hosts (prokaryotes, yeasts), highlights skilful applications of our basic understanding to improve membrane protein production. Omics technologies provide new concepts to engineer microbial hosts for membrane protein production.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Highly concentrated bioethanol production requires less volume in fermentation tanks and conserves distillery energy. We screened osmotolerant yeasts from a collection of 1699 yeast strains at our ...institute and found that three strains, NFRI3062, NFRI3213, and NFRI3225, were candidates for use in bioethanol production. All of these strains belonged to
Saccharomyces cerevisiae. NFRI3062 produced 15.0% (w/v) of ethanol from YPD medium containing 35% glucose cultivated at 30
°C for 60
h, while
S. cerevisiae NBRC0224, which has previously been reported suitable for ethanol production, only produced 13.0% (w/v). The thermotolerances of NFRI3213 and NFRI3225 were also superior to those of NBRC0224 and NFRI3062. We also demonstrated the simultaneous saccharification and fermentation (SSF) of very high gravity (VHG) potato mash and sweet-potato mash. NFRI3225 produced ethanol from potato mash at the fastest rate and in the highest volume (13.7% (w/v)) among the tested strains. The maximum productivity and ethanol yields were 9.1
g/L/h and 92.3%, respectively. Although the potato mash was not sterilized, bacterial contamination was not observed. This may have been due to the growth inhibition of bacteria by the rapid glucose consumption and ethanol production of NFRI3225 during the VHG-SSF process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Inhibitors released by the breakdown of plant cell walls prevent efficient conversion of sugar into ethanol. The aim of this study was to develop a fast and reliable inhibitor sensitivity assay for ...ethanologenic yeast strains. The assay comprised bespoke 96-well plates containing inhibitors in isolation or combination in a format that was compatible with the Phenotypic Microarray Omnilog reader (Biolog, hayward, CA, USA). A redox reporter within the assay permits analysis of inhibitor sensitivity in aerobic and/or anaerobic conditions. Results from the assay were verified using growth on spot plates and tolerance assays in which maintenance of viability was assessed. The assay allows for individual and synergistic effects of inhibitors to be determined. It was observed that the presence of both acetic and formic acid significantly inhibited the yeast strains assessed, although this impact could be partially mitigated by buffering to neutral pH. Scheffersomyces stipitis, Candida spp., and Pichia guilliermondii demonstrated increased sensitivity to short chain weak acids at concentrations typically present in lignocellulosic hydrolysates. S. cerevisiae exhibited robustness to short chain weak acids at these concentrations. However, S. stipitis, Candida spp., and P. guilliermondii displayed increased tolerance to HMF when compared to that observed for S. cerevisiae. The results demonstrate that the phenotypic microarray assay developed in the current study is a valuable tool that can be used to identify yeast strains with desirable resistance to inhibitory compounds found in lignocellulosic hydrolysates.
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CEKLJ, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The 3M™ Petrifilm™ Rapid Yeast and Mold (RYM) Count Plate is a simple, ready-to-use chromogenic culture method for the rapid detection and enumeration of yeast and mold in food products. The 3M ...Petrifilm RYM Count Plate method was compared to the U. S. Food and Drug Administration Bacteriological Analytical Manual (FDA BAM) Chapter 18, Yeasts, Molds and Mycotoxins and the ISO 21527:2008 Microbiology of Food and Animal Feeding Stuffs-Horizontal Method for the Enumeration for Yeast and Molds - Part 1: Colony Count Technique in Products with Water Activity Greater Than 0.95 and Part 2: Colony Count Technique in Products with Water Activity Less Than or Equal to 0.95 reference methods for raw almonds and raw frozen ground beef patties (77% lean). The 3M Petrifilm RYM Count Plate method was evaluated using a paired study design in a multi-laboratory collaborative study following the current AOAC Validation Guidelines. Three target contamination levels (low, 10-100 CFU/g; medium, 100-1000 CFU/g; high 1000-10 000 CFU/g) as well as an uninoculated control level (0 CFU/g) were evaluated for each matrix. Samples evaluated by the 3M Petrifilm RYM Count Plate method were prepared in duplicate and incubated at both 25°C and 28°C. Plates at both temperatures were enumerated after 48 and 60 h of incubation. No significant difference was observed between the 3M Petrifilm RYM Count Plate method and the FDA BAM or ISO 21527 reference methods for each contamination level. No statistical differences were observed between samples analyzed by the 3M Petrifilm RYM Count Plate method (at either 25°C or 28°C) and the reference methods. No statistical significant differences were observed between enumeration of colonies at 48 and 60 h on the 3M Petrifilm RYM Count Plate method and the reference methods.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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