Degradation of Extracellular β-(1,3)(1,6)- d -Glucan by Botrytis cinerea

Abstract

During growth on glucose, Botrytis cinerea produced extracellular j3-(1,3)(1,6)-D-glucan (cinerean), which formed an adhering capsule and slime. After glucose was exhausted from the medium, cinereanase activity increased from <0.4 to 30 U/liter, effecting a striking loss in the viscosity of the culture. Cinerean was cleaved into glucose and gentiobiose. Gentiobiose was then hydrolyzed to glucose. While cinereanase activity was strongest in the culture supernatant, gentiobiase activity was located mainly in the cell wall fraction. The addition of extra glucose or cycloheximide prevented the cinerean degradation caused by an effect on cinereanase formation. Cinerean degradation was accompanied by microconidiation and sclerotium formation. B. cinerea was found to grow on cinerean with the latter as its single carbon and energy source. In this case, cinerean degradation occurred during hyphal growth, and no microconidiation or sclerotium formation was observed. Growth experiments with various carbon sources indicated that cinerean had a positive effect on the formation of cinerean-degrading enzymes. Several microbial polysaccharides, e.g., xanthan, which has a wide range of applications ranging from its use as a thickening agent for food to that as a gelling agent for explosives, have been evaluated for potential industrial usage (39). 3-1,3-Glucans are especially interesting for their

Biochemistry and molecular biology of exocellular fungal β-(1,3)- and β-(1,6)-glucanases

“…Phanaerochaete chrysosporium produces an exocellular b-glucan on a glucose rich medium, but after glucose exhaustion, b-glucanase production increased, hydrolyzing this exocellular b-glucan and liberating glucose for growth (Bes et al, 1987). Similar functions have been suggested for b-glucanases from several other b-glucan producing fungi including Sclerotium glucanicum (Rapp, 1989(Rapp, , 1992, B. cinerea (Stahmann et al, 1992(Stahmann et al, , 1993 and Acr. persicinum, where other glucan-degrading enzymes like b-glucosidases may be involved in asisting them in this task (Pitson et al, 1997c).…”

Production and Characterization of Laccase from Botrytis cinerea 61-34

“…Earlier, the induction of laccase in B. cinerea cultures by 2,5-xylidine (4), by combinations of gallic acid and pectin (39), and by phenolic constituents presumed to be present in muscat grape juice (44) (31). A facile purification scheme for B. cinerea 61-34 laccase, following initial precipitation of coproduced 1,3-␤-glucan (35) with dilute acetone and then concentration and clarification by ultrafiltration, was completed by HIC on a phenyl-substituted column. Enzyme concentration by sequential physical procedures (stages IIIA and IIIB) resulted in a reproducible 15-to 20-fold purification by removal of nonspecific, lower polypeptides, as well as by protein entrapment on filters.…”

Adhesion of germlings of Botrytis cinerea

“…When grown in a liquid culture, B. cinerea secretes cinerean, a ␤-(1,3)(1,6)-D-glucan (9,26). This polysaccharide, which forms an adherent capsule about the mycelium (26), is resistant to degradation by several ␤-(1-3) glucanases (26,27), including some that can degrade laminarin, a ␤-(1-3) glucan of algal origin. Stahmann et al (26) have suggested that, among other functions, cinerean could serve as a fungal adhesive.…”