Dissertation Abstract

screening of Trichoderma spp. and their efficacy as a bio conversion agent of municipal solid waste through appropriate technique of solid state fermentation

Rahman, Ahsanur Ahsan  2009  Not applicable

Department of Botany, Rajshahi University (Bangladesh), 280 pp.

A total of 135 Trichoderma isolates were isolated from different locations of Rajshahi Metropolitan City and its sub urban areas and premises of compost plant of Natore Development Society (NDS), Natore. On the basis of morphological characteristics this 135 strains of Trichoderma were divided into 5 aggregate groups. Representative isolate from each group were sending for verification to the CABI Biosciences, Surrey, United Kingdom. The number of Trichoderma isolates were reduced to three species and identified as T. virens Miller et al. (IMI-392430) (22 isolates); T. pseudokoningii (Rifai) (IMI-392431) (27 isolates) and T. harzianum (Rifai) (IMI-392432, 392433 & 392434) (86 isolates). Chemical characteristics of samples were analyzed by the Soil Analysis Laboratory, Soil Resource Institute, Regional Office, Shampur, Rajshahi. Organic matter, P and K of the samples were significant and positively correlated with the cfu’s of Trichoderma but N was non significant and positively correlated. Samples moisture was also significant and positively correlated with the Trichoderma cfu’s and pH was non significant and positively correlated.
Identified five Trichoderma strains were screened to select the most effective strain for decomposition of organic solid waste (OSW). For this purpose autoclaved OSW was used and inoculated separately with spore suspension and culture disc of each Trichoderma strain in in vitro condition. Changes of color, odor, pH, volume loss and weight loss of decomposed OSW were noted after 10, 20 and 30 days, and temperature was noted after 3 days of intervals up to 30 days. The highest decomposition activity in term of weight loss and volume loss was exhibited in spore suspension treatment using T. harzianum IMI-392432 strain. Combine treatment of Trichoderma strains had promising effect in the process of decomposition of OSW and the combination of T. harzianum IMI-392432 + T. harzianum IMI-392433 + T. harzianum IMI-392434 was the most effective and exhibited 18.04 % greater weight loss than control. Further, identified five Trichoderma strains were also screened in in vitro condition to select the most potential antagonistic isolates of Trichoderma as biocontrol agent against Alternaria tenuis a fruit rot pathogen of chili by dual culture technique and poison agar, modified by layer poison agar and culture filtrate method. From the results it was also observed that used Trichoderma strains possessed different degrees of ability to suppress or inhibit the mycelia growth of A. tenuis, and T. harzianum IMI-392432 showed the best performances. In dual culture technique the highest percentages of inhibitory growth rate (PIRG) and minimum colony overgrowth time was recorded in T. harzianum IMI-392432. In both method poison agar and modified by layer poison agar secondary metabolites of T. harzianum IMI-392432 was the most effective and showed the highest PIRG value against A. tenuis. In culture filtrate treatment it was also exhibited that T. harzianum IMI-392432 was significantly i