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MIG1, encoding a C2H2 zinc-finger repressor protein implicated in carbon catabolite repression, was discovered to be involved in non-sexual flocculation of Saccharomyces cerevisiae. Disruption of MIG1 in a flocculent mutant strain of NCYC 227, produced a non-flocculent phenotype. Expression of MIG1 on a 2 micro pRS426 vector in a non-flocculent strain, YM 4134, caused flocculation. MIG1 on a high-copy-number LEU2-d plasmid caused intense flocculation in the same strain. Mutations in the SSN6 and TUP1 genes confer a flocculent phenotype in non-flocculent strains of S. cerevisiae.

Non-sexual flocculation of the yeast Saccharomyces cerevisiae NCYC 227 strains involves a 13 kDa cell-wall-surface protein bound to mannose. The proteins binds in mannose in the presence of calcium and forms aggregates. Flocculation of the yeast cells occurring due to hydrogen bonding between the protein and mannan indicates protein aggregation inhibition at high temperatures and the urea content.

Based on a three level Box Behnken design involving the variables pH (X1), incubation temperature (X2) and fermentation time (X3), a response surface methodology for the production of carotenoid by a mutant Aspergillus carbonarius CFTRI-UV10046 was standardized. Data analyzed using a second order polynomial equation resulted in the optimized process condition of 46.7 h growth at 29.30C in a corn flour medium of pH 3.3 for carotenoid production. Under these conditions the model predicted 1283.00 ?g of carotenoid /g of dry fungal biomass which is 52.19% higher then the initial medium. With regard to biomass, 2.44 g dry weight/100 ml culture medium was obtained after 56 h of growth at 29.70C in the medium of pH-3.6. [ABSTRACT FROM AUTHOR]

Cell-wall antigenic studies on Saccharomyces species grown by fermentation in 20% glucose broth indicated S. cerevisiae to develop two antigens specific for this species. These antigens were heat-stable polysaccharides and agglutination studies using specific antiserum prepared by cross absorption indicated their localization on the cell-wall surfaces. Using species-specific antibody, the results presented describe a specific and rapid identification of S. cerevisiae by ELISA according to the classification system of Yarrow (1984). [ABSTRACT FROM AUTHOR]

The understanding that enzymatic degradation of fruit pectin can clarify juices and improve juice yields resulted in the search for microbial pectinases and application in vegetable- and fruit-processing industries. Identified enzymes were classified on the basis of their catalytic activity to pectin or its derivatives and in terms of industrial use. Discovery of gene sequences that coded the enzymes, protein engineering, and molecular biology tools resulted in defined microbial strains that over-produced the enzymes for cost-effective technologies. Recent perspectives on the use of pectin and its derivatives as dietary fibers suggest enzymatic synthesis of the right oligomers from pectin for use in human nutrition. While summarizing the activities of pectin-degrading enzymes, their industrial applications, and gene sources, this review projects another application for pectinases, which is the use of enzymatically derived pectin moieties in functional food preparation.

A techno-economic analysis of submerged (SmF) and solid state fermentation (SSF) processes for Aspergillus carbonarius polygalacturonase production was performed to make an appropriate process selection. The downstream processing involved integrated membrane process (IMP) and alginate affinity precipitation (AAP). For a production scale of 30kL purified polygalacturonase concentrate per year, the total upstream cost of SmF was 14% lower than the SSF process. Downstream processing cost by IMP was 47% lower than AAP. The SmF-IMP process required a total capital investment that was 15-24% lower than the SmF-AAP and SSF-AAP processes. The corresponding unitary product cost was also lower by 24-36% in SmF-IMP process. Thus the SmF-IMP process proved to be very attractive from an economic point of view., (Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

Aspergillus carbonarius, when grown by submerged and solid-state fermentation, produces different molecular forms of polygalacturonase (PG; EC 3.2.1.15), among them a 42 kDa PG with a high specific activity of 7000 U/mg protein. When the enzymes were purified by integrated membrane process (IMP) and alginate affinity precipitation (AAP), the two processes concentrated different forms of the enzyme. The AAP process selectively purified and concentrated the high active PG whereas the IMP yielded different PGs and also amylase and protease. Evaluation of the AAP enzyme preparations for apple juice preparation under conditions usually employed commercially demonstrated that the high activity PG did not result in good juice clarity. With IMP processed enzymes, juice yields and clarity were similar to that obtained with commercial PG from A. niger., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Purification of polygalacturonase (PG) from the cultures of Aspergillus carbonarius obtained by acetate buffer extraction after solid-state fermentation was attempted by integrated membrane process and alginate affinity precipitation. The carbohydrates were completely eliminated (98%-99%) with a PG recovery of 72%-80% during integrated membrane process, which would otherwise interfere with the purification process and lead to enzyme loss. However, specific activity of PG did not improve (1.19-1.21 fold) due to the presence of other similar molecular mass proteins. Under optimum conditions of affinity precipitation, the specific activity of PG enhanced to 2450 U/mg (4 fold) with almost complete elimination of carbohydrates and colour compounds resulting in a PG recovery of 61%. PG purity obtained with ultrafiltration (UF) was comparable with the conventional dialysis during desalting eluted PG, besides UF rendered a concentrated PG. The enzyme purity stated was as descend by SDS-PAGE. The results suggested suitability of affinity precipitation for PG purification from solid-state cultures and the potential of UF as a single step process for handling eluted PG., (Copyright (c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

A mutant Aspergillus carbonarius selected for temperature tolerance after UV treatment, when grown in shake flasks, produced mycelia bearing yellow pigment. Since the mutant was affected in sterol biosynthetic pathway, the pigment was apparently produced to maintain membrane fluidity and rigidity for growth sustenance in low-pH culture broth. Nuclear magnetic resonance analyses characterizing the pigment as a partially saturated canthaxanthin, containing beta-ionone end rings, suggested its application as a retinoid. When tested for this property in retinoic acid receptor expressing prostate cancer cell line, LNCaP, the fungal partially saturated canthaxanthin induced apoptosis. Low apoptosis percentage in DU145 prostrate cancer cells that does not express functional retinoic acid receptor-beta (RAR-beta) suggested binding specificity of the partially saturated canthaxanthin for RAR-beta.

A procedure to detect raw and gelatinized starch activities of glucoamylase on isoelectric focusing (IEF) gels by using 2, 3, 5-triphenyltetrazolium chloride is described. The reagent reacts with the reducing group of glucose released by glucoamylase from the substrate starch. Using the reaction, production of glucoamylase by Aspergillus niger was detected on 10% IEF gels within a pH range of 2.5-9.5. Since the method can detect raw and gelatinized starch activities of glucomylase associated with 1 microg protein, it will be useful for enzyme engineering studies that involve screening of various mutations.

In rapidly fermenting yeast, the rotenone insensitive mitochondrial NADH dehydrogenase was not completely repressed by high glucose. This activity appeared to enhance the glycolytic rate due to which acetaldehyde accumulated intracellularly. To overcome the toxicity of acetaldehyde, the strain produced stress proteins. During late stationary phase of growth, the accumulated acetaldehyde was converted to ethanol resulting in faster ethanol production.