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Preliminary studies of the decay mechanism of some brown-rot fungi
1989 - IRG/WP 1402
The importance of the enzymatic degradation of hemicellulose and cellulose by brown-rot fungi is still under discussion. Endo-ß-1,4-xylanase and endoglucanase activities of Coniophora puteana and Poria placenta cultures were measured by the increase in reducing groups. Enzymes were produced in liquid and solid sawdust based culture media. Enzyme activities were measured in two, four and eight week intervals from the beginning of the test. The ability of brown-rot fungi to degrade crystalline and noncrystalline cellulose by an enzymatic pathway was studied by measurement of total cellulase activities from Coniophora puteana and Serpula lacrymans. Low enzyme activities were noted. This result indicates strongly that these fungi possess a complete cellulose-degrading enzymatic pathway.
A-C Ritschkoff, H Viitanen

Fenton's reagent as a modification tool in brown-rot decay
1996 - IRG/WP 96-10155
A biomimetic approach was used to clarify the role and importance of the Fenton-type reaction in the carbohydrate degradation by brown-rot fungi. Spruce sawdust and microcrystalline cellulose were modified in the H2O2/Fe(II) treatment. The degree of hydrolysis of the pretreated spruce sawdust was clearly increased with the complete cellulase (Econase), purified endoglucanase from Trichoderma reesei and endoglucanase of Poria placenta. The oxidative pretreatment of microcrystalline cellulose decreased the hydrolyzability of pure cellulose with the complete cellulase, but the hydrolyzability with both purified endoglucanase of Trichoderma reesei and endoglucanase from Poria placenta was increased. Thus, after oxidative treatment with Fenton's reagent the hydrolysis of both pure cellulose and wood was substantially increased.
M Rättö, A-C Ritschkoff, J Buchert, L Viikari

Isolation of a putative endogenous endo-ß-1,4-glucanase (cellulase) from the midgut diverticulae of the wood-boring crustacean, Limnoria quadripunctata
2003 - IRG/WP 03-10494
Over the last 75 years, many workers have conducted research into the digestive biochemistry of Limnoria. Cellulolytic enzymes have been detected in crude extracts, although whether these are of endogenous or microbial origin has been in question. To elucidate the source of these enzymes, RNA was isolated from the midgut diverticulae of Limnoria quadripunctata. Reverse transcription polymerase chain reaction (RT-PCR) was performed using degenerate primers derived from conserved regions of known endoglucanases. This produced a fragment of cDNA that was extended by rapid amplification of complementary DNA ends (RACE). The overlapping cDNA fragments were cloned and sequenced, and the amino acid sequence of a putative protein was deduced. BLAST analysis was performed to determine the similarity between this sequence, and those of known proteins. The results indicated a conserved structural domain of a glycosyl hydrolase, and the greatest sequence homology was to endo-ß-1,4-glucanases from termite species. In situ hybridisation was performed using labelled sense and antisense probes. This indicated the presence of a cellulase-encoding mRNA in the tissues of the midgut diverticulae. These results provide the strongest evidence to date of endogenous endoglucanase production by Limnoria.
J Dymond, M J Guille, S M Cragg