Abstract:
Cellulase and antibiotic producing by isolated actinomycetes were studied. One hundred fifteen actinomycetes strains were isolated from soil samples collected from 11 provinces in Thailand. Seventy one percent of these isolated strains showed cellulolytic activity by forming clear zone around colony on carboxymythylcellulose agar. NKP3-2 strain isolated from Krok Phra District, Nakhon Sawan Province exhibited the highest cellulolytic activity by the ratio of clear zone and colony diameter at day 7 of 4.3 centimeter. LK3-10 strain isolated from Koh Kha District, Lam Phang Province and NV1-4 strain isolated from Viang Sa District, Nan Province showed the ratio of 2.9 and 3.8 centimeter, respectively. Study of cellulase activity of strain NKP3-2 showed the highest cellulase activity of 390.38 mU/ml. Antimicrobial activity assay by Dual-culture method against 6 species of plant pathogenic fungi, included Pythium aphanidermatum DOAC 1662, Phytophthora parasitica DOAC 0005, Collectotrichum capsici DOAC 1196, Fusarium oxysporum f.sp. lycopersici DOAC 0874, Fusarium oxysporum f.sp. cubense DOAC 0893 and Alternaria porri DOAC 1756. The NKP3-2, LK3-10 and NV1-4 strain exhibited the broad spectrum antimicrobial activity against all 6 tested fungi. LK3-10 isolated showed highest antifungal activity against Pythium aphanidermatum (γ=31mm.) and Fusarium oxysporum f.sp. lycopersici. (∆γ=11.7mm) NKP3-2 strain showed high activity against Pythium aphanidermatum. (∆γ=28.8 mm.) NV1-4 strain was also inhibited Pythium aphanidermatum (∆γ=25.2mm.) and Fusarium oxysporum f.sp. lycopersici (∆γ=9.5 mm.) at lower level when comparing with to the LK3-10 and NKP3-2 strain.
Molecular identification of the nucleotide sequence of the 16s rRNA gene of NKP3-2 isolated strain showed 98% similarity closely related to Streptomyces sp. 1A01654. LK3-10 isolated strain showed 99% similarity closely related to 3 Streptomyces sp. included Streptomyces AB2A, Streptomyces hygroscopicus subsp. hygroscopicus and Streptomyces hygroscopicus. NV1-4 isolated strain showed 100% similarity closely related to Streptomyces hygroscopicus strain 3088.
So the three promising isolated strain which showed cellulase and antimicrobial activity against plant pathogenic fungi could be able to use in the application of compost making, which will be useful in agricultural practice.