Aspergillus fumigatus isolates were tested with three antifungals by flow cytometry (FC) and fluorescenceactivated cell sorting. FC results after 4 h correlated well with MICs obtained by the NCCLS M38-A method; voriconazole exhibited fungicidal activity, albeit to a lesser extent than amphotericin B, but to a greater extent than itraconazole.

Three medicinal plants, Aloe vera, Mentha arvensis and Ocimum sanctum were explored for endophytic actinomycetes diversity, plant growth promoting and antimicrobial activity. Endophytic actinomycetes were most commonly recovered from roots (70% of all isolates) followed by stems (17.5%) and leaves (12.5%), respectively. Single genus Streptomyces ranked first (60% of all isolates) followed by Micromonospora (25%), Actinopolyspora (7.5%), and Saccharopolyspora (7.5%). The highest numbers of endophytic actinomycetes were isolated from Ocimum sanctum (45%). Out of 22 isolates tested, 12 showed the ability to solubilize phosphate in the range of 5.4-16.5 mg/100 ml, while 16 isolates produced indole-3 acetic acid (IAA) ranging between 8.3-38.8 µg/ml. Nine isolates produced the amount of hydroxamate-type of siderophore ranging between 5.9-64.9 µg/ml and only four isolates were able to produce catechol-type of siderophore in the range of 11.2-23.1 µg/ml. Of the nine, interestingly, eight endophytic actinomycetes (88.9%) showed a significant antagonistic activity against one or more phytopathogenic fungi indicating their possible role as plant biocontrol agents. An extended infection of root tissues of Ocimum sanctum by Saccharopolyspora O-9 was observed using transmission electron microscope (TEM).

Isolation of endophytic actinomycetes is an important step to screen antimicrobial compounds to curb the threat of drug-resistant strains of human pathogens. Out of the 50 endophytic actinomycetes obtained from surface sterilized root, stem and leaf tissues of Syzygium cumini, 50 isolates (30%) exhibited antimicrobial activity. Antistaphylococcal activity was displayed by most of the isolates, with maximum percent inhibition by J-10 (Mean of Inhibition Factor=12.12 mm2). A total of 8 isolates (4 each) were able to hydrolyse protein (proteinase activity) and solubilize chitin (chitinase activity). Results of thin layer chromatography confirm the production of chloramphenicol family |antibiotic by the isolate J-5. This is the first report providing an insight into untapped endophytic actinomycete milieu of Syzygium cumini yet to be explored which might be a promising source for novel antimicrobial agents.

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