Cellulolysis by Rumen Micro-organisms

Halliwell, G.

doi:10.1099/00221287-17-1-153

Cited by 62 publications

(27 citation statements)

References 18 publications

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“…Exoglucanase (EC 3.2.1.91) activity was measured either with filter paper by the method of Mandels & Weber (1969) or with cotton dewaxed by the method of Halliwell (1957). For the latter assay, the reaction mixture consisted of 1 ml culture filtrate and 20 mg dewaxed Texas cotton in 1 ml 0.1 M-acetate buffer pH 5 containing 0.02% (w/v) NaN,; after incubation at 37 OC for 18 h, the soluble sugar produced was determined by the phenol/H,SO, method of Dubois et al (1956).…”

Section: E T H O D Smentioning

confidence: 99%

Factors Influencing the Production of Cellulase by Aspergillus fumigatus (Fresenius)

Stewart¹,

Parry²

1981

Microbiology

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During growth in liquid culture containing a single cellulosic or non-cellulosic carbon source, a newly isolated strain of Aspergillus fumigatus released cellulases into the medium; the amounts produced depended on the nitrogen source, the type and concentration of the carbon source, pH and temperature. Extracellular cellulolytic activity was still increasing after incubation for 60 d with 1 % (w/v) C F 11 cellulose, (NH,),SO, as nitrogen source and a starting pH of 7. The activities of the new isolate were compared with those of A. fumigatus IMI 143864 and Trichoderma reesei QM6a (ATCC 13631) and it was shown to be a good producer of /?-glucosidase.

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Section: E T H O D Smentioning

confidence: 99%

Factors Influencing the Production of Cellulase by Aspergillus fumigatus (Fresenius)

Stewart¹,

Parry²

1981

Microbiology

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“…The cellulose suspension formed was diluted with distilled water to give a 2 (w/v) suspension, and this was stored at 2 "C. Dewaxed cotton yarn was kindly given by Scandura, Cleckheaton, Yorkshire, and was of the type used for conveyor belt carcasses (Walsh & Stewart, 1971). It was cut into short pieces and partially untwisted before being dewaxed by the method of Halliwell (1957). a-Cellulose, unless stated otherwise, was a-cellulose fibre (approximately 995 %; Sigma) used without further treatment.…”

Section: B J H S T E V E N S a N D J P A Y N Ementioning

confidence: 99%

Cellulase and Xylanase Production by Yeasts of the Genus Trichosporon

Stevens

Payne

1977

Journal of General Microbiology

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filtrates by Trichosporon cutaneum and T. pullulans were determined. With ball-milled filter paper as a test substrate maximum activity was detected 4 to 7 days after transfer from glucose to cellulose (ball-milled filter paper) as growth substrate. Comparison of the yeast filtrates with those from the moulds Trichoderma viride and Myrothecium verrucaria showed that the total activity of one strain of T. pullulans was comparable to that of the moulds with ball-milled filter paper as assay substrate. Activities were always lower when a-cellulose or dewaxed cotton were used as assay substrates. The main products of cellulose degradation were ,cellobiose and glucose, although the ratio of these products clearly differentiated between culture filtrates of the species examined. Xylanase activity was present in all the culture filtrates examined. Polyacrylamide gel electrophoresis of active filtrates produced strainspecific patterns of three to five stained bands with similar mobilities but an inactive filtrate lacked one band common to all the other filtrates.

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“…(a) Rumen micro-organisms and extracts were examined for ' cellulase' by the assay method described earlier (Halliwell, 1957), except that lyophilized powders, acetone powders and enzyme extracts were incubated for 72 hr. instead of 40 hr.…”

Section: G Halliwellmentioning

confidence: 99%

Cellulolytic preparations from Micro-organisms of the Rumen and from Myrothecium verrucaria

Halliwell¹

1957

Journal of General Microbiology

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SUMMARY: A study has been made of the degradation of different forms of cellulose (' cellulolysis '), comprising soluble substituted derivatives (carboxymethylcellulose), insoluble cellulose powder, swollen cellulose, hydrocellulose and native cotton fibres, by concentrated suspensions of mixed rumen micro-organisms and by the aerobic fungus Myrothecium verrucaria. Mixed rumen micro-organisms are shown to be one of the most powerful sources of cellulolytic enzyme, in that they produce almost complete solubilization of all the above forms of cellulose in a relatively short period ( 3 days). Enrichment cultures of rumen micro-organisms were prepared by growing concentrates of mixed micro-organisms on cellulose powder. Cellulolysis was followed by determining the cellulose disappearance, formation of cellulolytic activity and gas evolution. Freeze-dried powders and their derived acetone powders obtained from washed concentrated supensions (non-enrichment cultures) of mixed rumen micro-organisms solubilized up to 80% of insoluble cellulose powder. Cell-free extracts were isolated : (a) from concentrated suspensions and from freeze-dried powders of rumen micro-organisms by extraction with butanol ; (b) from concentrated suspensions of enrichment cultures by grinding with alumina at low temperature. The butanol extracts solubilized cellulose powder to a small extent (10 yo solubilization) and were more effective against the soluble carboxymethylcellulose. In contrast, the alumina extracts were more active against insoluble cellulose (30 yo solubilization) but were only weakly active against carboxymethylcellulose. Cell-free filtrates from Myrothecium verrucaria, an aerobic fungus much used in work on cellulose metabolism, were shown to possess cellulolytic properties very similar to those of alumina extracts from enrichment cultures of rumen microorganisms. The significance of the results is discussed in relation to the mode of breakdown of cellulose.Despite much work, little appears to be known about the conditions governing the biological breakdown of cellulose. Many workers have obtained extracts, from animal, vegetable and microbial sources, with only feeble activity on insoluble forms of cellulose, and have turned to using as substrates extensively degraded cellulose or even the soluble substituted cellulose derivatives. Whilst such substrates usually prove to be more susceptible to hydrolysis, they leave the primary question unanswered, namely, how is true or insoluble cellulose hydrolysed for utilization by a select group of micro-organisms ? Numerous examples of ' cellulase ' preparations which fail to attack insoluble cellulose with any significance are given in an excellent monograph by Siu (1951). More recent cases are quoted by Halliwell(l957) where calculations show that hydrolysis of cellulose powder or cotton never exceeds more than about 6 yo of the substrate.Despite the feeble action demonstrated by these extracts, the parent organism, whether fungus or bacterium, is often capable of producing complete

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Cellulolysis by Rumen Micro-organisms

Cited by 62 publications

References 18 publications

Factors Influencing the Production of Cellulase by Aspergillus fumigatus (Fresenius)

Factors Influencing the Production of Cellulase by Aspergillus fumigatus (Fresenius)

Cellulase and Xylanase Production by Yeasts of the Genus Trichosporon

Cellulolytic preparations from Micro-organisms of the Rumen and from Myrothecium verrucaria

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