Detoxification of Corn Stover and Corn Starch Pyrolysis Liquors by Ligninolytic Enzymes of Phanerochaete chrysosporium

Phanerochaete chrysosporium (ATCC 24725) shake flask culture with 3 mM veratryl alcohol addition on day 3 was able to grow and detoxify different concentrations of diluted corn stover (Dcs) and diluted corn starch (Dst) pyrolysis liquors [10, 25, and 50% (v/v)] in defined media. GC-MS analysis of reaction products showed a decrease and change in some compounds. In addition, the total phenolic assay with Dcs samples demonstrated a decrease in the phenolic compounds. A bioassay employing Lactobacillus casei growth and lactic acid production was developed to confirm the removal of toxic compounds from 10 and 25% (v/v) Dcs and Dst by the lignolytic enzymes, but not from 50% (v/v) Dcs and Dst. The removal did not occur when sodium azide or cycloheximide was added to Ph. chrysosporium culture media, confirming the participation of lignolytic enzymes in the detoxification process. A concentrated enzyme preparation decreased the phenolic compounds in 10% (v/v) corn stover and corn starch pyrolysis liquors to the same extent as the fungal cultures

Reactor design for hazardous waste treatment using a white rot fungus

Various nutrient media and reactor configurations have been explored in order to grow the white rot fungus Phanerochaete chrysosporium, induce its active enzyme, develop kinetic data for the degradation of 2-chlorophenol, and use chemical engineering analysis to design an efficient reactor. Preliminary experiments indicated that the biodegradation rate was improved by two to three orders of magnitude when the fungus was immobilized. As a result, emphasis shifted to two types of reactor design: a packed-bed reactor employing a silica-based porous support, and a fluidized-bed reactor employing alginate beads. Both were very effective in degrading 2 chlorophenol at inlet concentrations up to 520 ppm. Apparent Michaelis-Menten kinetic rate constants were developed for both reactors. To our knowledge, these are the first such constants to be published for this fungus

Biological methods for detoxification of corn stover and corn starch pyrolysis liquors

Biological methods were developed to detoxify corn stover and corn starch pyrolysis liquors produced at 400--500°C. Prokaryotic and eukaryotic suspended cells and biofilms were employed for the detoxification process. The continuous of detoxification process was monitored by measuring the change in dissolved oxygen and pH. Total phenolic assay, change in UV absorbance spectra, GC-MS analysis and bioassay were performed to determine the detoxification. Pseudomonas putida and Streptomyces setonii biofilms, developed on Plastic Composite Supports (PCS) fixed to agitator shaft of benchtop computer controlled bioreactor, detoxified 10 and 25% (v/v) diluted corn stover and corn starch pyrolysis liquor (Des and Dst), while mixed culture biofilms detoxified 50% (v/v) Dcs and Dst.;Ligninolytic enzymes of Phanerochaete chrysosporium were also employed to detoxify the Dcs and Dst in shake flask cultures. The detoxification was determined by measuring the activity of lignin peroxidase (LiP), mangenase peroxidase (MnP), total phenolic compounds reduction, GC-MS analysis, and bioassay. Ph. chrysosporium culture detoxified 10 and 25% (v/v) Dcs and Dst, but not 50% (v/v) Des and Dst. The involvement of ligninolytic enzymes in the detoxification process were confirmed by adding ligninolytic enzymes inhibitors, sodium azide and cycloheximide to culture medium and by employing concentrated crude enzyme to detoxify 10% (v/v) Dcs.;In a subsequent study, the ligninolytic enzymes were produced by Ph. chrysosporium PCS biofilm in stirred tank bioreactor. Fourteen repeated batch fermentations were performed with different culture conditions. The differences in enzymes production between the batches were determined statistically by comparing the activity of LiP and MnP. All batch conditions evaluated enhanced the production of at least one of the enzymes. In batch C3V0 11 and C3V3 8 (continuous aeration, 300 agitation, and addition of veratryl alcohol on day zero or three) LiP and MnP were produced on day three and reached a peak on day six. However, in batch C3VM0 14 (continuous aeration, 300 agitation, and addition of veratryl alcohol and MnSO4 on day zero) LiP and MnP were produced earlier, on day three, and decreased by day six

Production and regulation of lignin degrading enzymes from Lentinus squarrosulus (mont.) Singer and Psathyrella atroumbonata Pegler

The influence of metal ions on the production and regulation of ligninase and mycelia extension of two type Basidiomycetes (Lentinus squarrosulus and Psathyrella atroumbonata) cultivated on lignocellulose waste was investigated. Mn2+ and Ca2+ ions stimulated growth of both fungi and mycelia extension significantly. Ligninase production increased two to twelve fold under the influence of Mn2+ and Ca2+ ions at concentrations of 20 to 80 mM. Mg2+ and K+ ions did not stimulate growth and extension of fungal mycelia, rather fungal cultures became deactivated after six days. The importance of mycelia extension and enhanced enzyme production has biotechnological applications in wood and pulp, textile and tanning, as well as in oil industries. Key words: Basidiomycetes, Lentinus squarrosulus, Psathyrella atroumbonata, ligninase, cofactors. African Journal of Biotechnology Vol.2(11) 2003: 444-44

Investigation of reactor design parameters towards optimizing biodegradation of chlorophenols by phanerochaete chrysosporium

The biodegradation of 2,4,6-trichlorophenol (246-TCP) and 2,4,5-trichiorophenol (245-TCP) by Phanerochaete chrysosporium was studied in batch and in continuous systems. Contrary to most of the previous reports from the literature, this study shows that degradation of both TCPs can occur in the absence of any measurable ligninase activity. The microorganism did not retain its degradative ability for more than about two weeks In order to better understand the degradation process, the individual contributions of both the biomass and the extracellular proteins were studied separately. The results show that neither the biomass nor the extracellular proteins alone can completely degrade 246-TCP, but both are required for complete degradation to occur. In addition, it was found that the rate of degradation is directly proportional to the concentration of the total extracellular protein produced by the fungus. The extracellular enzyme system (other than ligninase) responsible for degradation has a life time of 32 to 45 hours (depending upon the pH of the system). On the basis of these observations, a reaction scheme for the degradation process is proposed in which 246-TCP is first attacked by an extracellular protein (enzyme) secreted by the fungus, described by a Michaelis-Menten kinetic expression, and then finally degraded by the cell bound protein (enzyme). The kinetic parameters were determined in continuous reactor experiments and successfully tested for other configurations. Optimal operating parameters were determined for a packed-bed continuous reactor. Degradation of phenol and pentachlorophenol were also studied for comparative purposes