Isolation and evaluation of antibiosis by streptomyces from soils of different levels of salinity
Loading...
Date
2001
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sokoine University of Agriculture
Abstract
This study was undertaken to isolate and screen for antibiosis Streptomyces from soils of different levels of salinity. Soil samples for the study were obtained from the Coast region (Chalinze Mzee) and Morogoro region (near Catholic Capuchin Seminary, Kikundi Primary School, Mkata Ranch and SUA farm). Soil samples were analysed for pH, EC, exchangeable bases, % organic carbon, total nitrogen and texture using appropriate methods.Enumeration of Streptomyces was done by the
plate count method using starch casein agar. Isolation to obtain pure isolates was done on oatmeal agar. Antibiosis testing was carried out on nutrient agar, against Clavibacter michiganensis sub sp. Michiganensis, Xanthomonasphaseoli, Xanthomonasvasicatoria, Xanthomonas Xanthomonas phaseolicoli oryzae pv var fuscoris, oryzae and Acidovorax avenae. Colour of aerial mycelium and morphology of spore chains were determined.S/rep/o»zyces population ranged from (logio) 2.0
to 4.9 per gram of soil. The study revealed that soil characteristics such as exchangeable bases, extractable phosphorus, organic carbon, and clay content had no significant effect on the number of Streptomyces, while ntotal nitrogen and salinity (electrical conductivity) had significant effects.The Streptomyces isolates from different levels of salinity were of various colours such as blue, brown, red, white and their colour inlergrades. The spore chains’ morphologies of the Streptomyces isolates
from different soils of different levels of salinity ranged from flexuous. Straight, open spirals, open
loops and monoverticillate.All the Streptomyces isolates were able to grow on media of salt concentration of less than 2%. Some were able to grow on media of salt concentrations between 2% and 8%. No isolate grew on media of 10% salt concentration. The Streptomyces showed different degree of antibiosis. Some isolates had strong antibiosis against the test plant pathogenic bacteria, while some had moderate and others had weak antibiosis. Some isolates did not show antibiosis.
Description
Masters Theses
Keywords
Streptomyces, Soil microorganisms, Saline soils, Soil microbiology, Antibiosis, Microbial ecology, Actinomycetales