Isolation and characterization of efficient cellulolytic fungi from degraded wood and industrial samples

Cellulose is the most abundant biopolymer and renewable natural product in the biosphere. Cellulose degrading fungal strains play an important role in recycling of cellulosic materials. They have immense advantage in various industries to hydrolyze cellulosic substrates for production of various products. This study was thus aimed to isolate and characterize efficient cellulose degrading fungi from their common natural habitats. Decaying Acacia wood and industrial water effluent samples were used for isolation and screening of cellulolytic fungi. Both samples were serially diluted and cultured on cellulose basal medium (CBM) supplemented with 30 mg/L chloramphenicol as bactericidal agent. Cellulose degrading fungal isolates were selected based on their hydrolyzed zone after congo red dye stain. Among 13 initial isolates, four isolates (C, E, G, and H) were finally screened as the most efficient fungal isolates representing only degraded Acacia tree. These isolates were confirmed as Penicillium species (C), Apergillus terrus (G), Alternaria species (H) and Apergillus species (E). From this study, the decaying Acacia sample was found to be the best source for cellulolytic fungi than that of wastewater sample. Out of these isolates, the maximum zone of hydrolysis (51.33±1.53 mm) was obtained for ‘isolate E’, whereas the minimum zone of clearance (26.67±1.53 mm) was recorded for penicillium species. This study indicates the existence of potential cellulolytic fungal on decayed wood of Acacia. Hence, further molecular aided characterizations of the isolates and their enzymes are of paramount importance for their use for industrial purposes.Keywords: Cellulase, cellulosic basal medium, congored, fungi, zone of hydrolysi

Biodiversity of the Genus Trichoderma in the Rhizosphere of Coffee (Coffea arabica) Plants in Ethiopia and Their Potential Use in Biocontrol of Coffee Wilt Disease

The present study investigated the distribution status and biodiversity of Trichoderma species surveyed from coffee rhizosphere soil samples from Ethiopia and their potential for biocontrol of coffee wilt disease (CWD) caused by Fusarium xylarioides. Trichoderma isolates were identified based on molecular approaches and morphological characteristics followed by biodiversity analysis using different biodiversity indices. The antagonistic potential of Trichoderma isolates was evaluated against F. xylarioides using the dual confrontation technique and agar diffusion bioassays. A relatively high diversity of species was observed, including 16 taxa and 11 undescribed isolates. Trichoderma asperellum, T. asperelloides and T. longibrachiatum were classified as abundant species, with dominance (Y) values of 0.062, 0.056 and 0.034, respectively. Trichoderma asperellum was the most abundant species (comprising 39.6% of all isolates) in all investigated coffee ecosystems. Shannon’s biodiversity index (H), the evenness (E), Simpson’s biodiversity index (D) and the abundance index (J) were calculated for each coffee ecosystem, revealing that species diversity and evenness were highest in the Jimma zone (H = 1.97, E = 0.76, D = 0.91, J = 2.73). The average diversity values for Trichoderma species originating from the coffee ecosystem were H = 1.77, D = 0.7, E = 0.75 and J = 2.4. In vitro confrontation experiments revealed that T. asperellum AU131 and T. longibrachiatum AU158 reduced the mycelial growth of F. xylarioides by over 80%. The potential use of these Trichoderma species for disease management of F. xylarioides and to reduce its impact on coffee cultivation is discussed in relation to Ethiopia’s ongoing coffee wilt disease crisis