Rare actinomycetes in mangrove soils and leaf litter

Actinomycetes are one of the major sources for the discovery of novel bioactive compounds. A total of 226 actinomycete strains were isolated from Morib mangrove soils and leaf litter samples in Malaysia. The actinomycete populations ranged from 6.0 x lO" to 20.0 x 10' colony-forming units (cfu)/g dry sample. Total populations and tentative distributions of actinomycetes varied significantly with the different types of mangrove samples. The tentative genus diversity in mangrove soil and leaf litter was Micromonospora, 49%; Streptosporangium, l7%; Streptomgces, 7%; Actinomadura, 4%; Saccharomonospora, 2% and others (Microbispora, Nocardia, Dactylosporangium and Actinoplanes) 2O%. Micromonospora and Streptosporangium were the dominant genus observed in mangrove rhizosphere soil and leaf litter samples. A total of 72 different isolates were selected based on variation of colony morphology and mycelial colour on the isolation agar plate for characterization. Thirty three (46%) isolates produced aerial mycelium and 13 (18%) isolates produced a range of diffusible pigments on MMS agar plates. Mesodiaminopimelic acid (DAP) isomer was observed in 33 (46%) isolates