Several phototrophic microorganisms, principally cyanobacteria species predominantly sheathed forms occur as biofilms on the exposed surface of stone temples, monument as well as building facades receiving areas. A study was conducted to analyse the potential of six sub-aerial cyanobacteria species belonging to three genera, i.e. Scytonema, Tolypothrix and Westiellopsis which were recorded as the main components in the biofilms isolated from 10 different sub-aerial sites (six building facades, three stone temples and one mortar monument) of Bhubaneswar and Puri, Odisha under laboratory culture conditions. The sub-aerial cyanobacteria strains were morphological characterized and changes in their biochemical constituents were analyzed in terms of total chlorophyll- a, total soluble protein, total carotenoids, total phycobiliproteins including phycocyanin, phycoerythrin and allophycocyanin, total cellular carbohydrate and extracellular polysaccharides in response to different time interval culture in BG-11 media. The analysis showed that maximum amount of total chlorophyll- a in Scytonema hyalinum (8.98µgml-1) and minimum in Westiellopsis prolifica (3.78µgml-1). On other hand, total soluble protein content increased with incubation time and maximum amount were recorded in two species Tolypothrix rechingeri and Scytonema bohneri (95.76µgml-1 and 90.76µgml-1), while species Westiellopsis prolifica showed minimum content of soluble protein (27.90µgml-1) as compared to other strains examined. Maximum amount of total carotenoids were recorded in Tolypothrix rechingeri (2.54µgml-1) and total phycobiliproteins in Scytonema bohneri (5.99µgml-1). The results of phycobilin analysis of investigated sub-aerial cyanobacteria showed phycocyanin (PC) to be dominant phycobiliproteins with maximum value recorded in three species Tolypothrix rechingeri, Scytonema bohneri, Scytonema hyalinum and lowest in Scytonema hofman-bangii. On the contrary, Scytonema hofman-bangii recorded highest phycoerythrin (2.28µgml-1). Total cellular carbohydrate were recorded maximum during 28th day growth in Tolypothrix rechingeri (78.76µgml-1) and minimum in Scytonema hyalinum (44.9µgml-1) whereas, the total extracellular polysaccharides contents were found to be higher in Tolypothrix rechingeri and Scytonema ocellatum on 32th days growth (64.54µgml-1 and 58.98µgml-1 respectively). Study showed that Qualitative phytochemical screening of sub-aerial cyanobacteria revealed its bioactive phytochemical constituents to be alkaloids, phenol and Flavonoid etc. Acetone, methanol and chloroform are better and more efficient solvent extractors of the bioactive phytochemical constituents which vary from species to species. However, the overall response during the investigation it was observed sub-aerial cyanobacteria are prolific producers of primary and secondary metabolite(s) that may act as the antimicrobial drug resource in addition to their much explored marine and freshwater counterpart. This study is expected to contribute to data base for the drugs discovery as raw material for both biotechnological applications as well as in industrial uses for benefit of future generation.

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