Overproduction of lignin-degrading enzymes by an isolate of Phanerochaete chrysosporium

Abstract

Phanerochaete chrysosporium is a white rot fungus which secretes a family of lignin-degrading enzymes under nutrient limitation. PSBL-1 is a mutant of this organism that generates the ligninolytic system under nonlimiting conditions during primary metabolism. Lignin peroxidase, manganese peroxidase, and glyoxal oxidase activities for PSBL-1 under nonlimiting conditions were 4to 10-fold higher than those of the wild type (WT) under nitrogen-limiting conditions. PSBL-1 was still in the log phase of growth while secreting the enzymes, whereas the WT had ceased to grow by this time. As in the WT, manganese(II) increased manganese peroxidase activity in the mutant. However, manganese also caused an increase in lignin peroxidase and glyoxal oxidase activities in PSBL-1. Addition of veratryl alcohol to the culture medium stimulated lignin peroxidase activity, inhibited glyoxal oxidase activity, and had little effect on manganese peroxidase activity in PSBL-1, as in the WT. Fast protein liquid chromatography (FPLC) analysis shows production of larger amounts of isozyme H2 in PSBL-1 than in the WT. These properties make PSBL-1 very useful for isolation of large amounts of all ligninolytic enzymes for biochemical study, and they open the possibility of scale-up production for practical use.

Fungal pretreatment of lignocellulose by Phanerochaete chrysosporium to produce ethanol from rice straw

“…Medium Optimization Using the Plackett-Burman Design P. chrysosporium produced both MnP and LiP; however, in our preliminary experiments, the fungal growth rate was slow and the maximum overall activity of MnP and LiP (i.e., 1,300 and 800 U/L, respectively) was much lower when the medium was optimized to maximize the activity of LiP than those (i.e., 2,600 and 500 U/L, respectively) when optimized for MnP. Also, in previous studies, the volumetric activity of MnP dominated that of LiP in the cultures of P. chrysosporium whether lignin was present (e.g., kraft pulp) (Archibald et al, 1997) or not (Orth et al, 1991). Therefore, MnP was selected as the target enzyme for medium optimization.…”

“…For measuring the enzyme activity of LiP, the oxidation of VA to veratraldehyde was monitored at 310 nm (Teunissen and Field, 1998;Tien and Kirk, 1984). The GLOX activity was determined by measuring the formation of H 2 O 2 using a modified peroxidase-coupled assay (Kersten and Kirk, 1987;Orth et al, 1991;Teunissen and Field, 1998).…”

“…Because the deconstruction of lignin results in improved accessibility of cellulose for cellulase, the production of sugars during enzymatic hydrolysis is significantly enhanced by processes that deconstruct lignin (Chen and Dixon, 2007;Jeffries, 1990). Therefore, many studies have been conducted to evaluate the production and purification of lignolytic enzymes such as LiP, MnP, and laccase (Kersten and Kirk, 1987;Leisola et al, 1985;Orth et al, 1991;Tien and Kirk, 1984). Furthermore, a few studies have been conducted to evaluate the direct treatment of lignocellulose by lignindegrading fungi or other microorganisms to determine if such processes can increase the enzymatic digestibility of lignocellulose by cellulase (Keller et al, 2003;Shi et al, 2009;Shrestha et al, 2008).…”

Physiology and molecular biology of the lignin peroxidases of Phanerochaete chrysosporium

“…apparently during primary metabolic phase). Orth et al [49] isolated a mutant (PSBL-1) of P. chrysosporium BKMF-1767 that produced LiPs and MnPs at 4-10-fold higher levels than those produced by the wild-type under nitrogen non-limiting conditions. Furthermore, this mutant has been reported to produce LiPs and MnPs during primary metabolism.…”

Potential for Bioremediation of Xenobiotic Compounds by the White‐Rot Fungus Phanerochaete chrysosporium

“…This is true in part because research into xenobiotic degradation by white-rot fungi has focused primarily on P. chrysosporium, a microorganism that requires low nitrogen for the onset of lignin degradation and special culture conditions (often static). Not only do other white-rot fungi need to be screened for the ability to degrade pollutants under a wide range of environmental conditions (Field et al, 19931, but genetic manipulation of P. chrysosporium toward the creation of a ligninase-overproducing mutant or secondary metabolism-deregulated strains could also be beneficial for future applications of this organism in the commercial remediation of pollutants (Orth et al, 1991;Tien and Myer, 1990;Kakar, 1994). Furthermore, optimization studies show that biodegradation rates increase manyfold when P. chrysosporium is immobilized.…”