Production of large multienzyme complex by aerobic thermophilic fungus Chaetomium sp. nov. MS-017 grown on palm oil mill fibre.

AIMS: A novel xylanolytic multienzyme complex of the aerobic thermophilic fungus Chaetomium sp. nov. MS-017 was produced on palm oil mill fibre (POMF) and partially characterized. METHODS AND RESULTS: The assay of the extracellular enzymes of Chaetomium sp. nov. MS-017 on POMF in solid-state fermentation revealed cellulolytic, pectinolytic and extremely high xylanolytic activities. The protein was purified by Sephadex G-200 column chromatography. The SDS-PAGE demonstrated that the purified protein is a complex with at least five xylanolytic, four cellulolytic and eight pectinolytic components. The characterization of the complex at various temperatures showed that the reactivity and stability of the complex are not lost up to 60 degrees C. In addition, the complex was very stable in a wide range of pH (3-9) and at high concentrations (10 mm) of cations and EDTA. The major products of xylan hydrolysis by the purified complex were determined to be xylobiose and xylotriose by thin-layer chromatography. CONCLUSION: Chaetomium sp. nov. MS-017 preferentially produces a xylanolytic multienzyme complex on POMF in solid-state fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the xylanolytic multienzyme complex produced by an aerobic thermophilic fungus.

Isolation of a novel thermophilic fungus Chaetomium sp. nov. MS-017 and description of its palm-oil mill fiber-decomposing properties.

Palm-oil mill fiber (POMF) is a fibrous, natural hard material discharged in enormous amounts from palm-oil mills in tropical plantations; therefore, research to find microorganisms that decompose POMF was conducted. As the result of screening, a new thermophilic fungus, Chaetomium sp. nov. MS-017, exhibiting rapid growth on POMF was isolated from rotted wood. Based on partial characterization of the decomposition of POMF, it was shown that MS-017 preferentially assimilates polysaccharides, especially hemicelluloses such as xylan. A preliminary composting study indicated that MS-017 produced 855 g of decomposed product from 1,000 g of intact POMF in 12 days under optimized solid-culture conditions. The decomposition rate of POMF was 23% (w/w), and the cell yield calculated from consumed POMF was as high as 36% (w/w). These results indicate that MS-017 has a very high potential to decompose POMF and that it is suitable for economical production of compost to recycle by-product biomass from oil-palm plantations.

A growth-promoting factor for human myeloid leukemia cells from horse serum identified as horse serum transferrin.

A growth-promoting factor for human myeloid cells was purified to apparent homogeneity from horse serum by a combination of gel filtration, blue Sepharose affinity chromatography, Mono Q anion-exchange chromatography, Mono P chromatofocusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The growth promoter was an iron-bound, single glycopolypeptide chain with a molecular weight of 84,000, an isoelectric point of 5.4 and an amino terminal sequence of Glu-Gln-Thr-Val-Arg-Trp-Cys-Thr-Val-Ser-Asn-His-Glu-Val-Ser-Lys-. According to the results of the amino acid sequence, iron binding ability and physicochemical properties, we identified the growth-promoting factor as horse serum transferrin. It was highly active in promoting the proliferation of a human monocytic leukemia cell line, THP-1, as well as of two other human myeloid cell lines, HL-60 and K-562. It had the same activity in proliferating THP-1 cells as 5% fetal calf serum-supplemented medium. Horse serum transferrin could be substituted for human or bovine serum transferrin.