Antimicrobial Haplindole Alkaloids as Chemical Marker for Rapid Identification of Stigonematales (Cyanobacteria)

Abstract

Antimicrobial Hapalindole alkaloids have been identified in the order Stigonematales. Being exclusively present in a few members of this order, they can easily serve as a good chemical marker for their identification. In the present experiment, some locally isolated cyanobacterial strains were identified on the basis of these chemical compounds. Cyanobacterial strains were isolated from natural samples through standard techniques. Their antimicrobial activity was tested against various fungal and bacterial strains, which include: Psuedomonas syringe, Escherichia coli, Bacillus cereus, Pseudomonas putida, Salmonella sp., Fusarium oxysporum, Cercospora canescens and Colletotricum dematium. Of the several natural isolates, two strains showed strong antimicrobial activity against most of the tested microorganisms. Isolates showing antimicrobial activity were further subjected to DART-MS analysis to identify the chemical compounds. Mass spectra revealed the presence of a range of hapalindole alkaloids, which were confirmed through their exact mass measurement, elemental composition determination, and fragment ion generation in the DART source. Quantitative analysis was conducted by measuring relative abundance.