Complex sentence: These naturally occurring compounds are generated as fermentation products by Streptomyces avermitilis, a soil Actinomycete, 8 different avermectins were isolated in 4 pairs of homologue compounds with a major (a-component) and minor (b-component) component usually in ratios of 80:20 to 90:10.
Split into simpler sentences: These naturally occurring compounds are generated as fermentation products by "Streptomyces avermitilis", a soil actinomycete. Eight different avermectins were isolated in 4 pairs of homologue compounds, with a major (a-component) and minor (b-component) component usually in ratios of 80:20 to 90:10.