From the oasis of Cholistan, true branching heterocystous cyanobacterial strains were studied for, the cell arrangement in primary branches being mono- or bi-seriate; the shape of cells in main filament large and irregular; profused secondary branching emerging on one or both sides and tapering along their length. In these observed traits, two clear morphological taxa were recognized, both well-assorted from the previously described species of the genus Westiellopsis. Both strains showed culturing responses and were studied for antibacterial, cytotoxic, and anticancer potentials. The strain derived from the site B-10 provenance exhibited antibacterial activity against Pseudomonas (18 mm), Klebsiella (15 mm), Staphylococcus (22 mm). On the contrary, the strain of site A-44 showed no activity against any of the above-mentioned bacterial strains. The cytotoxicity assay for the strain of the B-10 site showed 36% larval mortality, whereas strain A-44 showed 24% larval mortality. Performance of the strain B-10 in MTT assay (assessed on HCT-116 cell lines) revealed a dose-dependent activity: at 200, 100, 50, and 25 µg/ml; achieving a growth inhibition of 50.15%, 40.22%, 33.72%, and 10.21%, respectively; and the strain of A-44 could only exhibit a 30.06% growth inhibition at 200 µg/ml. The 16S rRNA sequencing revealed the sequence homology with Neowestiellopsis. Based on data presented here we report two diverse taxa of true branching Nostocales from Cholistan oasis, Pakistan.
Keywords: 16S rRNA; Cholistan; Cyanobacteria; morphology.
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