Bio-prospecting of soil Streptomyces and its bioassay-guided isolation of microbial derived auxin with antifungal properties

• Published in: Journal de mycologie médicale Vol. 28; no. 3; pp. 462 - 468
• Main Authors: Saravana Kumar, P., Yuvaraj, P., Gabrial Paulraj, M., Ignacimuthu, S., Abdullah Al-Dhabi, N.
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01-09-2018
• Subjects: Antifungal activity; Antifungal Agents - metabolism; Antifungal Agents - pharmacology; Auxin; Biological Assay - methods; Indoleacetic Acids - metabolism; Indoleacetic Acids - pharmacology; Microbial Sensitivity Tests; Mycological Typing Techniques; Phenyl acetic acid; RNA, Fungal - analysis; RNA, Fungal - isolation & purification; RNA, Ribosomal, 16S - analysis; Soil Microbiology; Streptomyces - classification; Streptomyces - genetics; Streptomyces - isolation & purification; Streptomyces - metabolism; Streptomyces collinus BG4; Antifungal activity; Auxin; Streptomyces collinus BG4; Phenyl acetic acid
• ISSN: 1156-5233; 1773-0449
• DOI: 10.1016/j.mycmed.2018.05.009

The present study was aimed to isolate bioactive actinomycetes with antifungal properties. Twenty-seven distinct soil derived actinomycetes were investigated for their antifungal activities. Among these, one isolate exhibited significant antifungal activity. Phenotypic and 16s rRNA gene sequence analysis strongly suggested that the active isolate BG4 belonged to the genus Streptomyces. Further, the chemical investigation of the active extract resulted in the isolation of a major compound and it was structurally elucidated as phenyl acetic acid (PAA). PAA exhibited promising antifungal activity with 100% inhibition, ranging from 31.25 to 25μg/mL. It is to be noted that PAA is naturally occurring and biologically active auxin. In addition, it has also been hypothesized that phytohormone endorsing the source of soil-symbionts has similar pathways for synthesizing compounds and its congeners of host due to horizontal gene transfer. These findings demonstrate that microbially derived phytohormone can be used to treat fungal infections.