Screening and genetic improvement of pectinolytic fungi for degumming of textile fibers

Abstract

Aiming at contributing to technological improvements in plant fiber processing methods, this paper reports research work on the obtainment of more efficient pectinase-producing fungi strains. More specifically, this work reports the analysis of 18 strains of filamentous fungi, with the purpose of obtaining enzymes for textile fibers degumming. The strains were evaluated for production of pectinolytic enzymes under several growth conditions (culture medium and growth temperature). Production of pectinases was measured by an enzymatic index (EI) in solid pectin medium. Among the tested strains, Penicillium chrysogenum IFO 4626 (Q 176) showed the best performance. Genetic improvement of this strain was carried out to increase its pectinase production, while keeping cellulase activity down to a negligible level, since cellulases are known to decrease the resistance of the fiber. Variability was induced through several cycles of mutation and selection by exposing conidea to ultraviolet light (UV). We selected 39 out of 390 isolated colonies. Resulting mutants produced nine times more pectin lyase (PL) than the original strain in terms of PL specific activity, and five times more in terms of PL activity (i.e. mmoles liberated per minute of reaction per mL of medium). Periodically, mutant performance was evaluated in solid pectin medium. Genetic stability was maintained for four years after isolation.

Specific adaptation of Ustilaginoidea virens in occupying host florets revealed by comparative and functional genomics

“…The pectinolytic activities of phytopathogenic fungi were evaluated using pectin plate assays as described previously with minor modifications 69 . Different fungi were grown on the pectin-containing media (1 l medium: 5.0 g pectin, 1.0 g yeast extract, 0.5 g glucose, 2.0 g KH 2 PO 4 , 1 g (NH 4 ) 2 SO 4 , 0.9 g Na 2 HPO 4 , trace of MnSO 4 , 15 g agar, pH 7.0).…”

Production, purification and biochemical characterization of an exo-polygalacturonase from Aspergillus niger MTCC 478 suitable for clarification of orange juice

“…The fungal strain Aspergillus niger MTCC 478 was procured from Microbial Type Culture Collection and Gene Bank, Institute of Microbial Technology, Chandigarh (India) and screened for pectinase production by plate assay method (Molina et al 2001). The culture was maintained by cultivation on Czapek-Dox agar slants at 26°C.…”

Purification and characterization of an exo-polygalacturonase secreted by Rhizopus oryzae MTCC 1987 and its role in retting of Crotalaria juncea fibre

“…Organism and growth conditions Nine fungal strains: Aspergillus niger (MTCC 404), Aspegillus flavus (MTCC 2456), Aspergillus fumigatus (MTCC 2508), Aspergillus foetidus (MTCC 151), Aspergillus versicolor (MTCC 3071), Oidiodendron echinulatum (MTCC 1356), Byssochlamys fulva (MTCC 505), Paenibacillus polymyxa (MTCC 122) and Rhizopus oryzae (MTCC 1987) were procured from Microbial Type Culture Collection and Gene Bank, Institute of Microbial Technology, Chandigarh (India), based on their source of isolation and habitat, and screened for pectinase production by plate assay method (Molina et al 2001). The fungal strain R. oryzae MTCC 1987 showing maximum PG activity was chosen for production in submerged fermentation conditions.…”