Effects of Phenolic Monomers on Enzymatic and Fermentation Activities of the Rumen Fungus, Neocallimastix Frontalis
The present study was undertaken to investigate the effects of phenolic monomers on the enzymes and fermentation activities of a rumen fungus, Neocallimastix frontalis, and to evaluate the ability of the fungus to colonize and degrade guinea grass which contained large amount of phenolic monomers...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2006
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| Online Access: | http://psasir.upm.edu.my/id/eprint/162/2/549012_IB_2006_8.pdf http://psasir.upm.edu.my/id/eprint/162/ |
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| Summary: | The present study was undertaken to investigate the effects of phenolic monomers on
the enzymes and fermentation activities of a rumen fungus, Neocallimastix frontalis,
and to evaluate the ability of the fungus to colonize and degrade guinea grass which
contained large amount of phenolic monomers. From 115 isolates of N. frontalis,
15 isolates of Piromyces mae and 3 isolates of Orpinomyces joyonii obtained from
rumens of cattle and buffalo, a representative isolate of each species was selected for
further studies on its cellulolytic activity. Neocallimastix frontalis B15, P. mae B6
and O. joyonii C3 were selected based on their good growth in straw and ball-milled
filter paper media, and on their ability to maintain zoosporogenesis and viability in
the subcultures. 14C-labelled bacterial (A. xylinum) cellulose was used to determine
the cellulolytic activity of the three rumen fungal species and the effects of phenolic
acids (ρ-coumaric and ferulic acids) on the activity. The results showed that N.
frontalis B15 had the highest cellulolytic activity, and the phenolic acids had an
inhibitory effect on the activity. Other N. frontalis strains isolated from buffalo (B9),
cattle (C20) and goat were (G8) further characterized for their cellulolytic activities,and a strain, N. frontalis B9, which showed the highest activity was chosen for
subsequent studies The enzymes produced by N. frontalis B9 grown in filter paper or guinea grass media
included, CMCase, FPase, xylanase, β-glucosidase and β-xylosidase. The maximum
production of all the enzymes was at 72 h of incubation. The activities of the
enzymes in filter paper media in descending order were: CMCase > xylanase >
FPase > β-glucosidase, and in guinea grass media were: xylanase >
carboxymethylcellulase > FPase > β-xylosidase > β-glucosidase. Phenolic
monomers were found to inhibit the production of the enzymes and fermentation
activity of N. frontalis B9 in varying degrees. Of the four phenolic monomers,
ρ-coumaric and ferulic acids were the most inhibitory and vanillin the least. The
fermentation end-products were also inhibited by the phenolic monomers.
Observations using scanning electron microscopy showed that N. frontalis B9 in
control cultures without phenolic monomers could extensively colonise and degrade
various tissues of guinea grass, but treatments with the phenolic monomers
significantly reduced the colonization and degradation of the grass fragments.
Phenolic monomers, particularly ρ-coumaric acid and ferulic acid also inhibited the
dry weight loss and reduction in the textural strength of the grass fragments by
N. frontalis B9, which indicated a reduction in the degradation of the grass
fragments. Neocallimastix frontalis B9 produced esterases that released ferulic and
ρ-coumaric acids from their methyl esters and guinea grass. Production of feruloyl
and ρ-coumaroyl esterases, coupled with the penetrative ability provided by fungal
rhizoids, provided a mechanism for the breakdown and subsequent utilization of the
phenolic ester-linked carbohydrates present in plant cell walls. |
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