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The MNT1 gene of the human fungal pathogen Candida albicans is involved in O-glycosylation of cell wall and secreted proteins and is important for adherence of C. albicans to host surfaces and for virulence. Here we describe the molecular analysis of CaMNT2, a second member of the MNT1-like gene family in C. albicans. Mnt2p also functions in O-glycosylation. Mnt1p and Mnt2p encode partially redundant α-1,2-mannosyltransferases that catalyze the addition of the second and third mannose residues in an O-linked man no se pentamer. Deletion of both copies of MNT1 and MNT2 resulted in reduction in the level of in vitro mannosyltransferase activity and truncation of O-mannan. Both the mnt2Δ and mnt1Δ single mutants were significantly reduced in adherence to human buccal epithelial cells and Matrigel-coated surfaces, indicating a role for O-glycosylated cell wall proteins or O-mannan itself in adhesion to host surfaces. The double mnt1Δmnt2Δ mutant formed aggregates of cells that appeared to be the result of abnormal cell separation. The double mutant was attenuated in virulence, underlining the importance of O-glycosylation in pathogenesis of C. albicans infections.

NCBI PubMed ID: 15519997
Publication DOI: 10.1074/jbc.M411413200
Journal NLM ID: 2985121R
Publisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: n.gow

abdn.ac.uk
Institutions: School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK, School of Life Sciences, Wellcome Trust Building, University of Dundee, Dundee, UK, AstraZeneca R and D Boston, Waltham, MA, USA, Molecular and Cellular Biology Building, University of Minnesota, Minneapolis, USA, Division of Medical Mycology, Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, USA, Department of Medical Microbiology, Polwarth Building, University of Aberdeen, Aberdeen, UK
Methods: methylation, DNA sequencing, GC-MS, TLC, HPAEC, biological assays, radiolabeling, enzymatic digestion, HPAEC-PAD, extraction, cloning, ESI-QTOF-MS, cell growth, enzymatic assay, reductive beta-elimination, TEM, beta-elimination

Extractive fermentation technique or in situ product recovery process is a novel technique to segregate the desired product simultaneously in a fermentation process. For economic and high yield production of pullulan, Extractive fermentation process was applied fermentation process of A. pullulans. Aqueous Two Phase system (ATPS) systems were designed with various molecular mass of PEG (400, 600, 4000 and 6000) and dextran or mono/bi-sodium phosphate salts. Systems with short Tie Line length (TLL) 6.7 and 7.5% w/w for PEG-Salt and PEG-dextran respectively were chosen. Volume ratio for all the systems was kept constant at 1.0 and pH 7.0 for PEG-dextran and PEG-NaH2PO4 was maintained, whereas pH 9.0 was kept for PEG-Na2HPO4. A. pullulans, was found to be viable with PEG-NaH2PO4 and PEG-dextran systems. The biomass partitioned in the PEG rich top phase and the exopolysaccharide pullulan shown affinity towards the bottom phase. A maximum yield (36.47 g/L) was found with PEG 4000-Dextran 500 system of extractive fermentation process. The proposed process aptly integrates upstream and downstream process for continuous production and recovery of pullulan from the biomass, thus reducing the time quotient of the whole process.

NCBI PubMed ID: 30631089
Publication DOI: 10.1038/s41598-018-37314-y
Journal NLM ID: 101563288
Publisher: London: Nature Publishing Group
Correspondence: kashyapdubey

gmail.com)
Institutions: Microbial Process Development Laboratory University Institute of Engineering and Technology Maharishi Dayanand University, Rohtak, India, Bioprocess Engineering Laboratory, Department of Biotechnology Central University of Haryana, Mahendergarh, India
Methods: IR, TLC, enzymatic digestion, cell growth, spectrophotometry, optical density measurement