Biodegradation of gossypol by the white oyster mushroom, Pleurotus florida, during culturing on rice straw growth substrate, supplemented with cottonseed powder

The capacity of the white oyster mushroom, Pleurotus florida to biodegrade gossypol was studied, when grown on rice straw supplemented with cottonseed powder. The mushroom fruiting bodies did not contain any residues of gossypol at concentrations of cottonseed powder 0.15-0.60% nitrogen contents of...

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Bibliographic Details
Published in:World journal of microbiology & biotechnology 2001-04, Vol.17 (3), p.221-227
Main Authors: RAJARATHNAM, S, SHASHIREKHA, M. N, BANO, Zakia
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Bacteria
Biodegradation
Biological and medical sciences
Edible fungi production
Fundamental and applied biological sciences. Psychology
General agronomy. Plant production
gossypol
Microbiology
Pleurotus florida
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Summary:The capacity of the white oyster mushroom, Pleurotus florida to biodegrade gossypol was studied, when grown on rice straw supplemented with cottonseed powder. The mushroom fruiting bodies did not contain any residues of gossypol at concentrations of cottonseed powder 0.15-0.60% nitrogen contents of rice straw at the end of mycelial ramification. However, the cottonseed supplementation (at 0.30% N level itself) caused a doubling in the mushroom yield and its protein content, per unit weight straw substrate. The mushroom mycelium when grown on synthetic medium in liquid cultures was able to biodegrade gossypol. A pre-incubation period of 5 days before the addition of gossypol into the culture medium, an inoculum load 10 mg and an incubation period of 10 days at 25 °C caused the biodegradation of 100 μg gossypol. Increased concentrations of gossypol required increased duration and increased inoculum levels to effect biodegradation. However, the effect was more pronounced with an increase in inoculum density. The fungal monoculture when grown in rice straw (powder) (5%) + glucose (1%) liquid culture medium, showed an increase in hexosamine content and laccase activity that produced an increased degradation of gossypol over an incubation period from 5 to 25 days. Enzymic extracts of the mycelial monoculture raised on the chopped rice straw substrate when incubated with 100 μg of gossypol demonstrated its biodegradability; the increase in enzyme concentration showed enhanced gossypol degradation. This study adds to the world list of organic compounds that Pleurotus is able to biodegrade, and explains the cause of non-yellowing of the white oyster mushroom (P. florida) fruiting bodies, during culture on rice straw with supplementation of cottonseed powder for enhancing the mushroom yields.[PUBLICATION ABSTRACT]
ISSN:0959-3993
1573-0972
DOI:10.1023/A:1016603510901