Bioactive endophytic streptomycetes from the Malay Peninsula.

Area of Science:

• Microbiology
• Mycology
• Plant Pathology

Background:

• Endophytic microorganisms reside within plant tissues, offering a rich source of novel bioactive compounds.
• Plants with ethnobotanical uses are often reservoirs of unique microbial diversity.
• Streptomycetes are known for producing a wide array of secondary metabolites with diverse bioactivities.

Purpose of the Study:

• To isolate and characterize novel endophytic streptomycetes from ethnobotanically significant plants in the Malay Peninsula.
• To evaluate the antifungal and antibacterial activities of the isolated strains.
• To determine the genetic distinctiveness of the novel isolates using rRNA gene sequencing.

Main Methods:

• Isolation of endophytic bacteria from Thottea grandiflora, Polyalthia spp., and Mapania sp.
• Scanning electron microscopy for morphological characterization.
• Bioactivity screening against a panel of plant pathogenic fungi and bacteria.
• Molecular identification using rRNA gene sequencing and GenBank comparison.

Main Results:

• Three novel endophytic streptomycete isolates were obtained from the target plant species.
• All isolates exhibited significant antifungal activity against Phytophthora erythroseptica, Pythium ultimum, Sclerotinia sclerotiorum, Mycosphaerella fijiensis, and Rhizoctonia solani.
• No antibacterial activity was detected in any of the isolates.
• rRNA gene sequence analysis confirmed the isolates as distinct from known streptomycetes, though genetically related.
• Bioactive compounds were extractable in organic solvents.

Conclusions:

• Novel endophytic streptomycetes with potent antifungal properties were discovered in the Malay Peninsula.
• These isolates represent a promising source for developing new biofungicides to combat plant diseases.
• Further research into the chemical structures and modes of action of the antifungal compounds is warranted.