Preparation of 14C-radiolabelled lignocelluloses from spring barley of differing maturities and their solubilization by Phanerochaete chrysosporium and Streptomyces cyaneus

Mason, J. Clark; Birch, Olwen M.; Broda, Paul

doi:10.1099/00221287-136-2-227

Cited by 7 publications

(5 citation statements)

References 20 publications

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“…Organisms reported to solubilize grass lignins include Streptomyces viridosporus, S. baddius (Pometto & Crawford 1986), S. cyanus, Thermomonospora mesophila, and Actinomadura sp. (Mason et al 1988;Zimmerman & Broda 1989;Mason et al 1990). …”

Section: Solubilization Of Lcc By Microbial Activitymentioning

confidence: 99%

Biodegradation of lignin-carbohydrate complexes

Jeffries

1990

Biodegradation

176

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Covalent lignin-carbohydrate (LC) linkages exist in lignocellulose from wood and groups herbaceous plants.In wood, they consist of ester and ether linkages through sugar hydroxyl to the a-carbanol of phenylpropane subunits in lignin. In grasses, ferulic and p-coumaric acids are esterified to hemicelluloses and lignin, respectively. Hemicelluloses also contain substituents and side groups that restrict enzymatic attack. Watersoluble lignin-carbohydrate complexes (LCCs) often precipitate during digestion with polysaccharidases, and the residual sugars are more diverse than the bulk hemicellulose. A number of microbial esterases and hemicellulose polysaccharidases including acetyl xylan esterase, ferulic acid esterase, and p-coumaric esterase attack hemicellulose side chains. Accessory hemicellulases include a-L-arabinofuranosidase and a-methyl-glucuranosidase. Both of these side chains are involved in LC bonds. [~-Glucosidase will attach sugar residues to lignin degradation products and when carbohydrate is attached to lignin, lignin peroxidase will depolymerize the lignin more readily.A b breviations: APPL -acid precipitable polymeric lignin; CB Qase -cellobioquinone oxidoreduct ase; LClignincarbohydrate; LCC(s) -lignin-carbohydrate complex; DHP -Dehydrogenative polymerisate; DMSO -dimethylsulfoxide; DP -degree of polymerisation; MWEL -milled wood enzyme lignin; MWL -milled wood lignin (not digested with carbohydrases)

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Section: Solubilization Of Lcc By Microbial Activitymentioning

confidence: 99%

Biodegradation of lignin-carbohydrate complexes

Jeffries

1990

Biodegradation

176

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“…Mature [/ignin-14C]lignocellulose. Mason et al (1990) The temperature was reduced again to -160 O C and the sample was moved into the ante-chamber, where it was sputter-coated with gold. The material was then replaced in the cold stage to be examined.…”

Section: Methodsmentioning

confidence: 99%

“…Chemically synthesized radioisotopically labelled high molecular mass model lignin (dehydrogenative polymerizate, DHP) (Chua et al, 1983;Faix et al, 1985;Haider & Trojanowski, 1975;Kirk et al, 1975) is a better alternative, but this lacks the carbohydrate present in lignocellulose. In this study both lignocellulose (Crawford, 1981 ;Mason et al, 1990) were used to determine lignin degradation activity.…”

Section: Introductionmentioning

confidence: 99%

Informed strain improvement for lignin degradation by Phanerochaete chrysosporium

Wyatt

Broda²

1995

Microbiology

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The effect of breeding from the white rot fungus Phanemchaete chrysosporium ME446 on performance for lignin mineralization was examined. This model for informed strain improvement without mutagenesis is based on abundant restriction fragment length polymorphisms (RFLPs). Under optimized conditions for lignin mineralization, extracellular manganese peroxidase (MnP) but not lignin peroxidase (Lip) could be detected, so measurement of Lip activity is not a valid assay for lignin degradation. Mineralization of 14C-labelled synthetic lignin (14C-DHP) was used to compare the performance of the wild-type strain ME446 with those of sets of progeny strains. Meiotic progeny from strain ME446, heterokaryotic progeny of crosses between such strains, and meiotic progeny of one heterokaryotic strain were examined. In each case, a minority of strains performed more efficiently than the parental strain ME446. The greatest range of lignin-mineralization performance (70-fold) was found within the set of initial progeny of ME446 and the narrowest was within the set of secondary homokaryotic strains. This is consistent with the view that a moderate number of determinants contribute to lignin mineralization performance. However, performance did not correlate with the possession of any single allele of those for 38 previously defined RFLP markers. The results show that lignin mineralization performance can be improved by cycles of crosses and fruiting, without mutagenesis.

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“…As a result of this synergism, factors affecting the composition of the lignocellulose substrate, such as plant maturity, will determine the contribution that each enzyme makes in the fate of lignin from lignocellulose. This was shown in a recent study (Mason et al 1990) in which (U-14C) phenylalanine was injected into spring barley plants at frequent intervals during 140 d growth. Autoadiography of the plants revealed that, apart from high concentrations around the injection sites, radioactivity was evenly distributed throughout the plants.…”

Section: Lignocellulose Substratesmentioning

confidence: 99%

“…wheat and barley) grown in the presence of 14C phenylalanine Mason et al 1990), or 14C cinnamic acid (Benner et al 1984), or by dipping cut stems of woody plants in a buffer containing 14C ferulic acid (Crawford & Crawford 1978). In each case the radiolabelled acids provide a precursor for lignin biosynthesis.…”

Section: Lignocellulose Substratesmentioning

confidence: 99%

Biotechnology in the degradation and utilization of lignocellulose

Broda¹

1992

Biodegradation

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Lignocellulose is the predominant renewable resource. Its uses include fuel, as the feedstock for the pulp and paper industry, and for animal nutrition. It also constitutes a large proportion of agricultural and urban waste. Biotechnology has roles in its efficient production and utilisation. The types of lignin substrates available for study of lignin biodegradation are described. The white rot fungus Phanerochaete chrysosporium is the archetypal system for the study of lignocellulose degradation, since it mineralises lignin and degrades both cellulose and hemicellulose. The salient features of the P. chrysosporium system are described. The lignin peroxidases are a family of proteins, and it is shown that expression of their genes is differential. P. chrysosporium is heterokaryotic with two gene equivalents that have abundant RFLPs. A set of basidiospore-derived strains with genetic compositions defined by such RFLPs provided the potential basis for a strain improvement programme for lignin degradation. However, analysis of this system using radiolabelled synthetic lignin (DHP) as the substrate confirmed previous evidence that both the substrate and the fungal cultures displayed much variation, so that it was difficult to quantify performance for this property. The cellobiohydrolase I enzymes are also coded for by a family of genes, and evidence is also presented for allelic variants, for differential expression and for differential splicing. In contrast, the cellobiohydrolase II function is encoded at a unique genetic locus. Approaches to an homologous integrative transformation system are discussed. Some actinomycete bacteria represent an alternative system for lignin solubilisation in which strains differ in their spectra of activities on lignocellulose substrates. The xylanase system of Streptomyces cyaneus is shown to include three enzymes, two of which are inducible by xylan. A novel assay method was developed and used to demonstrate that the third is constitutive and also nonrepressible by glucose. It is proposed that this acts as a sensor for xylans in the environment that can yield breakdown products that are taken up and can then act as inducers of the other two enzymes. The studies on microbial lignocellulose degradation from different laboratories have allowed the formulation of specific biotechnological goals, and some of the problems and opportunities in this area are identified.

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Preparation of 14C-radiolabelled lignocelluloses from spring barley of differing maturities and their solubilization by Phanerochaete chrysosporium and Streptomyces cyaneus

Cited by 7 publications

References 20 publications

Biodegradation of lignin-carbohydrate complexes

Biodegradation of lignin-carbohydrate complexes

Informed strain improvement for lignin degradation by Phanerochaete chrysosporium

Biotechnology in the degradation and utilization of lignocellulose

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