A new assay for lignin-type peroxidases employing the dye azure B. (33/530)

The discovery in 1983 of fungal "ligninases" capable of catalyzing the peroxidation of nonphenolic aromatic lignin components has been seen as a major advance in understanding how certain basidiomycete fungi can completely degrade lignin. The ability of these lignin-type peroxidases to covert millimolar concentrations of veratryl alcohol to veratraldehyde, indicated by a change in the A310 of veratraldehyde, has become the standard assay for routine quantitation of LP activity. A new assay based on the oxidation of micromolar concentrations of the dye Azure B is presented. Although it is as simple and rapid as the veratryl alcohol assay, it appears to overcome some of the shortcomings of that assay. In particular, interference from UV- and short-wavelength visible-light-absorbing materials is greatly reduced and assay specificity is improved.  (+info)

Application of genome-wide expression analysis to identify molecular markers useful in monitoring industrial fermentations. (34/530)

Genome-wide expression analysis of an industrial strain of Saccharomyces cerevisiae identified the YOR387c and YGL258w homologues as highly inducible in zinc-depleted conditions. Induction was specific for zinc deficiency and was dependent on Zap1p. The results indicate that these sequences may be valuable molecular markers for detecting zinc deficiency in industrial fermentations.  (+info)

Antioxidative effects of glycosyl-ascorbic acids synthesized by maltogenic amylase to reduce lipid oxidation and volatiles production in cooked chicken meat. (35/530)

Glycosylated ascorbic acids were synthesized by using the transglycosylation activity of Bacillus stearothermophilus maltogenic amylase with maltotriose to show effective antioxidative activity with enhanced oxidative stability. The modified ascorbic acids comprised mono- and di-glycosyl transfer products with an alpha-(1,6)-glycosidic linkage. The antioxidative effects of the glycosyl derivatives of ascorbic acid on the lipid oxidation of cooked chicken breast meat patties were compared, and the synergistic effect when combined with alpha-tocopherol was determined in terms of thiobarbituric acid-reactive substances (TBARS) and volatiles production during storage. The results indicate that the glycosylated ascorbic acids had very effective antioxidative activity in preventing lipid oxidation, and were better in their synergistic effect in comparison to authentic ascorbic acid, with maltosyl-ascorbic acid being the most effective. Volatiles production was highly correlated with the TBARS values in the lipid oxidation of cooked meat. The antioxidative effect preventing the production of volatiles was particularly strong on pentanal, fairly strong on propanal and butanal, and not at all on ethanal. Propanal, pentanal, and the total volatiles thus provided a good representation of the lipid oxidation status of cooked chicken meat.  (+info)

Lightweight expanded clay aggregates (LECA), a new up-scaleable matrix for production of microfungal metabolites. (36/530)

In order to compare the effects of different growth matrices on secondary metabolite production we compared 16 Penicillium species known to produce several families of bioactive compounds. The isolates were grown in rich complex media formulated as semisolid (agar), liquid (still), shake culture, and absorbed in Lightweight Expanded Clay Aggregates (LECA). Both the number of metabolites and their quantities were compared via a chemo-diversity index. The matrix had a profound effect on fungal growth and secondary metabolism in some of the investigated species. LECA was shown to be a powerful alternative for production of sporulation-associated metabolites, such as cyclopenins and viridicatins, for quick up-scaling from agar based media, and as an alternative for production of metabolites that are not induced under submerse conditions.  (+info)

Purification of the extracellular pectinolytic enzyme from the fungus Rhizopus oryzae NBRC 4707. (37/530)

The pectinolytic enzyme from the solid-state culture of Rhizopus oryzae NBRC 4707 was purified to homogeneity by column chromatography on CM-Toyopearl 650 M and hydroxylapatite. The molecular weight of the enzyme was estimated by SDS-polyacrylamide gel electrophoresis to be 31,000 and was reduced to 29,700 after treatment with endoglycosidase H. Maximal activity was observed near pH 4.5 at 45 degrees C. The enzyme was shown to be endopolygalacturonase, as judged from the formation of oligogalacturonides as its reaction products. The addition of purified enzyme, as expected, enhanced the formation of lactic acid and ethanol in potato pulp grown with R. oryzae.  (+info)

Aquaporin-mediated improvement of freeze tolerance of Saccharomyces cerevisiae is restricted to rapid freezing conditions. (38/530)

Previous observations that aquaporin overexpression increases the freeze tolerance of baker's yeast (Saccharomyces cerevisiae) without negatively affecting the growth or fermentation characteristics held promise for the development of commercial baker's yeast strains used in frozen dough applications. In this study we found that overexpression of the aquaporin-encoding genes AQY1-1 and AQY2-1 improves the freeze tolerance of industrial strain AT25, but only in small doughs under laboratory conditions and not in large doughs under industrial conditions. We found that the difference in the freezing rate is apparently responsible for the difference in the results. We tested six different cooling rates and found that at high cooling rates aquaporin overexpression significantly improved the survival of yeast cells, while at low cooling rates there was no significant effect. Differences in the cultivation conditions and in the thawing rate did not influence the freeze tolerance under the conditions tested. Survival after freezing is determined mainly by two factors, cellular dehydration and intracellular ice crystal formation, which depend in an inverse manner on the cooling velocity. In accordance with this so-called two-factor hypothesis of freezing injury, we suggest that water permeability is limiting, and therefore that aquaporin function is advantageous, only under rapid freezing conditions. If this hypothesis is correct, then aquaporin overexpression is not expected to affect the leavening capacity of yeast cells in large, industrial frozen doughs, which do not freeze rapidly. Our results imply that aquaporin-overexpressing strains have less potential for use in frozen doughs than originally thought.  (+info)

Investigations on neomycin production with immobilized cells of Streptomyces marinensis NUV-5 in calcium alginate matrix. (39/530)

The purpose of this investigation was to study the effect of Streptomyces marinensis NUV-5 cells immobilized in calcium alginate for the production of neomycin. The effect of various parameters, such as the effect of alginate concentration (1%, 2%, 3%, 4%, and 5% wt/vol), the effect of cation (CaCl2, BaCl2, and SrCl2), the concentration of cation (0.01M, 0.125M, 0.25M, 0.375M, and 0.5M), the curing times (1, 6, 11, 16, and 21 hours), and the diameter of the bead (1.48, 2.16, 3.24, 4.46, and 5.44 mm), on neomycin production and bead stability were studied. The effect of maltose (4%, 3%, 2%, and 1% wt/vol) and sodium glutamate (0.6%, 0.3%, 0.15%, and 0.075% wt/vol) concentration on neomycin production was also studied. Better neomycin production was achieved with optimized parameters, such as alginate at 2% wt/vol, 0.25M CaCl2, 1-hour curing time, and 3.24 mm bead diameter. Effective neomycin production was achieved with 3% wt/vol maltose and 0.6% wt/vol sodium glutamate concentration. The repeated batch fermentations were conducted (every 96 hours) using the optimized alginate beads, employing the production medium with 3% wt/vol maltose and 0.6% wt/vol sodium glutamate along with mineral salts solution. The increase in antibiotic production was observed up to the 5th cycle, and later gradual decrease in antibiotic production was observed. Comparison of the total antibiotic production with free cells and immobilized cells was also done. An enhanced antibiotic productivity of 32% was achieved with immobilized cells over the conventional free-cell fermentation, while 108% more productivity was achieved over the washed free-cell fermentation. From these results it is concluded that the immobilized cells of S marinensis NUV-5 in calcium alginate are more efficient for the production of neomycin with repeated batch fermentation.  (+info)

Paenibacillus cineris sp. nov. and Paenibacillus cookii sp. nov., from Antarctic volcanic soils and a gelatin-processing plant. (40/530)

Seven strains of aerobic, endospore-forming bacteria were found in soil taken from an active fumarole on Lucifer Hill, Candlemas Island, South Sandwich archipelago, Antarctica, and four strains were from soil of an inactive fumarole at the foot of the hill. Amplified rDNA restriction analysis, 16S rDNA sequence comparisons, SDS-PAGE and routine phenotypic tests support the proposal of two novel species of Paenibacillus, Paenibacillus cineris sp. nov. and Paenibacillus cookii sp. nov., the type strains of which are LMG 18439T (=CIP 108109T) and LMG 18419T (=CIP 108110T), respectively. A further strain, isolated from a gelatin-production process, showed more than 99% 16S rDNA sequence similarity to the proposed P. cookii type strain and, although the gelatin isolate was atypical when compared with the fumarole isolates by repeated element primed-PCR, SDS-PAGE and phenotypic analyses, it was shown by DNA-DNA reassociation studies to belong to the same species. Strains of P. cookii produce spreading growth with motile microcolonies. Both species produce swollen sporangia that are typical for the genus, they both show 97.6% 16S rDNA sequence similarity to Paenibacillus azoreducens, they have 51.5-51.6 mol% G+C in their DNA and their major fatty acid is anteiso-C(15 : 0); however, fatty acids C(16 : 0) and anteiso-C(17 : 0) represent, respectively, 18 and 10 % of the total in P. cineris, but 11 and 20% in P. cookii.  (+info)