Improving the isolation of actinomycetes from soil by high-speed homogenization

Quantitative isolation of actinomycetes from five South African soils with different physical and chemical properties was conducted by hammer-mill comminution followed by high-speed liquid homogenization of resultant soil particles using a shaft homogenizer. Soil homogenates were serially diluted and plated in starch-casein agar and chitin agar for enumeration of isolates. For comparative purposes isolations were also conducted using conventional soil dilution techniques. The results were analysed using a GENSTAT computer program. Analysis showed that homogenization consistently suspended significantly greater numbers of spores from soil particles. Significant differences between magnitudes of actinomycete populations in different soils were also observed. During the initial standardization of the homogenization period required to separate maximum numbers of spores from the soil particles it was found that rates of suspension differed among soils and it is suggested that the particle size distribution and...