Screening statistical optimized production and application of β‐mannanase from some newly isolated fungi

摘要

Eighty‐eight fungi isolated from soil and decaying organic matter were screened for mannanolytic activity. Twenty‐eight fungi produced extracellular mannanase on locust bean gum as evidenced by zone of hydrolysis produced on mannan agar gel. Six prominent producers, including four species namely NFCCI 3282, NFCCI 3283, NFCCI 3284, NFCCI 3287 with NFCCI 3285 and NFCCI 3286 produced the β‐mannanase in the range of 84–140 nkat/mL. All these grew well on particulate substrates in solid‐state fermentation (SSF), producing relatively higher titers on mannan‐rich palm kernel cake (PKC) and copra meal. Two high yielding strains, (1747 nkat/gds) and (897 nkat/gds) were selected for statistical optimization of mannanase on PKC. Interaction of two critical solid state fermentation parameters, pH and moisture on mannanase production by these two molds was studied by response surface method. Optimized production on PKC resulted in three‐ to fourfold enhancement in enzyme yield was observed in case of . (5945 nkat/gds) and . (4726 nkat/gds). HPLC analysis of mannan hydrolysate indicated that and mannanase performed efficient hydrolysis of konjac gum (up to 99%) with exclusive mannooligosaccahride (DP of 4) production. A seminative SDS‐PAGE revealed that and produced three isoforms, produced two isoforms while , , and produced a single enzyme.