Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 54: 3880 - 3891. Published June 30, 2012.
Evaluation and optimization ofagro- industrialwastes for conidial production of Trichoderma isolates under solid state fermentation
Zuriash Mamo1 and Tesfaye Alemu1
1Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences,
Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia.
Corresponding author email: talemu2000@yahoo.com or tesfayealemu932@gmail.com
RESUME
Objective: The study aimed to evaluate, optimize and determine optimal growth conditions for the control of plant pathogens using high conidia production of Trichoderma isolates on different agro- industrial wastes (wheat straw, tea wastes, vegetable wastes, coffee husk and barley bran) under solid state fermentation (SSF). Methodology and Results: The optimum temperature, pH, moisture content, incubation period, inoculums size, inoculums load and effect of light were optimized for maximum conidia production of Trichoderma isolates. Among seven isolates of Trichoderma only isolates AUT1, AUT2, AUT4 and AUT7 which produced better conidia on potato dextrose agar medium (PDA) were taken for further study in this experiment. Among the substrates tested, wheat straw supported high conidia production of Trichoderma isolates AUT1, AUT2 and AUT4 (105± 5×108 conidia/g of substrate, 117±3.5×108 conidia/g of substrate and 144±6×108conidia/g of substrate respectively), followed by tea waste (92±3×108 conidia/g of substrate, 96.5±2.5×108 conidia/g of substrate and 119±12.5×108 conidia/g of substrate respectively). Trichoderma isolate AUT7 produced maximum conidia on vegetable wastes 405±19.9×108conidia/g of substrate. The optimum temperature for conidia production was between 200C and 30oC after 10 and 15 days of incubation. The optimum pH for conidia production was between 4.5 and 5.5 for all Trichoderma isolates except isolate AUT7 (pH 7.5). The optimum incubation period for high conidia production of Trichoderma isolates was 10 and 15 days. The optimum moisture content for conidia production of Trichoderma isolates was 35% and 40% after 5 and 10 days of incubation. The conidia production of Trichoderma isolates was maximum in the presence of light all isolates was best under solid state fermentation (SSF). Conclusions and application of findings: wheat straw, vegetable wastes and tea waste supported good conidia production of Trichoderma isolates under SSF. These wastes are better substrates for conidia production from economic and environmental point of view. The conidia production of Trichoderma isolates was maximal when cultivated in the presence of light than dark condition. The optimum inoculums size and load for conidia production of Trichoderma isolates was between 1ml and 2ml inoculums size and 1×106 conidia/ml inoculum load for all isolates except AUT7 (1×108 conidia/ml). Therefore, agro-industrial wastes were suitable for mass production of bioformulated products of Trichoderma isolates which are used for the control of coffee wilt disease (Fusarium xylarioides) in coffee growing areas of Ethiopia. Key words: Agro-industrial wastes, conidia production, solid state fermentation, Trichoderma isolates
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