Simple colorimetric method for detecting degenerate strains of the cultivated basidiomycete Flammulina velutipes (Enokitake).
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Degeneration of cultivated strains of Flammulina velutipes is a serious problem. We developed a simple colorimetric method to detect degenerate strains by using a liquid medium supplemented with bromothymol blue and lactose. The ability of a strain to develop normal mushrooms could be determined by the color of the medium. (+info)
Production of ethanol from starch by respiration-deficient recombinant Saccharomyces cerevisiae.
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A 100%-respiration-deficient nuclear petite amylolytic Saccharomyces cerevisiae NPB-G strain was generated, and its employment for direct fermentation of starch into ethanol was investigated. In a comparison of ethanol fermentation performances with the parental respiration-sufficient WTPB-G strain, the NPB-G strain showed an increase of ca. 48% in both ethanol yield and ethanol productivity. (+info)
Detection of fungi spectrum in industrial and home bakeries and determinated fungal allergy with skin prick test.
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Airborne fungal pathogens such as Penicillium, Aspergillus, Cladosporium, Trichophyton, and Alternaria may cause health problems. In this research, the fungal flora at different bakeries and their potential allergenic effects on the workers were investigated. We investigated 148 workers at 17 industrial type bakeries and 62 workers at 17 home type bakeries in Afyon. Our study was performed in two different seasons and climates, between January 2004 and June 2004. Fungal flora was detected by using Petri-dish method. In the winter, Penicillium was the dominant genus, while Cladosporium was the dominant genus during the summer, in both types of bakeries. The allergenic properties of dominant culturable fungi on workers involved in the bakeries were determined with the skin-prick test. It was found that with workers in the industrial type bakeries, the most common skin test positivity was caused by Penicillium. In the other hand, the skin test positivity, performed on workers in the home type bakeries, was equally caused by Penicillium, Trichophyton and Aspergillus. (+info)
Biocatalytic conversion of avermectin to 4"-oxo-avermectin: heterologous expression of the ema1 cytochrome P450 monooxygenase.
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The cytochrome P450 monooxygenase Ema1 from Streptomyces tubercidicus R-922 and its homologs from closely related Streptomyces strains are able to catalyze the regioselective oxidation of avermectin into 4"-oxo-avermectin, a key intermediate in the manufacture of the agriculturally important insecticide emamectin benzoate (V. Jungmann, I. Molnar, P. E. Hammer, D. S. Hill, R. Zirkle, T. G. Buckel, D. Buckel, J. M. Ligon, and J. P. Pachlatko, Appl. Environ. Microbiol. 71:6968-6976, 2005). The gene for Ema1 has been expressed in Streptomyces lividans, Streptomyces avermitilis, and solvent-tolerant Pseudomonas putida strains using different promoters and vectors to provide biocatalytically competent cells. Replacing the extremely rare TTA codon with the more frequent CTG codon to encode Leu4 in Ema1 increased the biocatalytic activities of S. lividans strains producing this enzyme. Ferredoxins and ferredoxin reductases were also cloned from Streptomyces coelicolor and biocatalytic Streptomyces strains and tested in ema1 coexpression systems to optimize the electron transport towards Ema1. (+info)
Characterization of alkaliphilic Bacillus strains used in industry: proposal of five novel species.
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Twenty alkaliphilic bacterial strains from industrial applications or enzyme studies were subjected to a polyphasic taxonomic investigation, including 16S rRNA gene sequencing, determination of genomic DNA G+C content, DNA-DNA hybridization, fatty acid analysis and standard bacteriological characterization. By comparing the groupings obtained based on the genomic DNA G+C content and the construction of a phylogenetic tree based on the 16S rRNA gene sequence, 12 clusters of similar strains were recognized. DNA-DNA hybridization revealed that these clusters represented five novel genospecies. Further analysis supported the proposal of five novel species in the genus Bacillus: Bacillus wakoensis sp. nov. (type strain N-1T=JCM 9140T=DSM 2521T), Bacillus hemicellulosilyticus sp. nov. (type strain C-11T=JCM 9152T=DSM 16731T), Bacillus cellulosilyticus sp. nov. (type strain N-4T=JCM 9156T=DSM 2522T), Bacillus akibai sp. nov. (type strain 1139T=JCM 9157T=ATCC 43226T) and Bacillus mannanilyticus sp. nov. (type strain AM-001T=JCM 10596T=DSM 16130T). (+info)
Cometabolism of citrate and glucose by Enterococcus faecium FAIR-E 198 in the absence of cellular growth.
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Citrate metabolism by Enterococcus faecium FAIR-E 198, an isolate from Greek Feta cheese, was studied in modified MRS (mMRS) medium under different pH conditions and glucose and citrate concentrations. In the absence of glucose, this strain was able to metabolize citrate in a pH range from constant pH 5.0 to 7.0. At a constant pH 8.0, no citrate was metabolized, although growth took place. The main end products of citrate metabolism were acetate, formate, acetoin, and carbon dioxide, whereas ethanol and diacetyl were present in smaller amounts. In the presence of glucose, citrate was cometabolized, but it did not contribute to growth. Also, more acetate and less acetoin were formed compared to growth in mMRS medium and in the absence of glucose. Most of the citrate was consumed during the stationary phase, indicating that energy generated by citrate metabolism was used for maintenance. Experiments with cell-free fermented mMRS medium indicated that E. faecium FAIR-E 198 was able to metabolize another energy source present in the medium. (+info)
Evaluation of pretreatment with Pleurotus ostreatus for enzymatic hydrolysis of rice straw.
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The effects of biological pretreatment of rice straw using four white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor, Ceriporiopsis subvermispora, and Pleurotus ostreatus) were evaluated on the basis of quantitative and structural changes in the components of the pretreated rice straw as well as susceptibility to enzymatic hydrolysis. Of these white-rot fungi, P. ostreatus selectively degraded the lignin fraction of rice straw rather than the holocellulose component. When rice straw (water content of 60%) was pretreated with P. ostreatus for 60 d, the total weight loss and the degree of Klason lignin degraded were 25% and 41%, respectively. After the pretreatment, the residual amounts of cellulose and hemicellulose were 83% and 52% of those in untreated rice straw, respectively. By enzymatic hydrolysis with a commercial cellulase preparation for 48 h, 52% holocellulose and 44% cellulose in the pretreated rice straw were solubilized. The net sugar yields based on the amounts of holocellulose and cellulose of untreated rice straw were 33% for total soluble sugar from holocellulose and 32% for glucose from cellulose. The SEM observations showed that the increase in susceptibility of rice straw to enzymatic hydrolysis by pretreatment with P. ostreatus is caused by partial degradation of the lignin seal. When the content of Klason lignin was less than 15% of the total weight of the pretreated straw, enhanced degrees of enzymatic solubilization of holocellulose and cellulose fractions were observed as the content of Klason lignin decreased. (+info)
Beneficial biofilm formation by industrial bacteria Bacillus subtilis and related species.
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Biofilms are densely packed multicellular communities of microorganisms attached to a surface or interface. Bacteria seem to initiate biofilm formation in response to specific environmental cues, such as nutrient and oxygen availability. Biofilms undergo dynamic changes during their transition from free-living organisms to sessile biofilm cells, including the specific production of secondary metabolites and a significant increase in the resistivity to biological, chemical, and physical assaults. Bacillus subtilis is an industrially important bacterium exhibiting developmental stages. It forms rough biofilms at the air-liquid interface rather than on the surface of a solid phase in a liquid, due to the aerotaxis of the cells. Biofilm formation by B. subtilis and related species permits the control of infection caused by plant pathogens, the reduction of mild steel corrosion, and the exploration of novel compounds. Although it is obviously important to control harmful biofilm formation, the exploitation of beneficial biofilms formed by such industrial bacteria may lead to a new biotechnology. (+info)