Cyanobacteria and microalgae growing on monuments of UNESCO World Heritage site Champaner Pavagadh, India: biofilms and their exopolysaccharide composition.

Abstract

The present study investigated the biofilm organisms growing on selected monuments of the Champaner Pavagadh complex (Gujarat, India), which is a UNESCO World Heritage Site. The cyanobacteria and microalgae were isolated from biofilms collected through non-destructive methods. The identification of these biological organisms was done using micro-morphological characters and confirmed by 16S rRNA gene sequencing. The exopolysaccharide of each of the isolated strains was extracted, hydrolysed and analysed by the HPTLC. Six isolated strains representing five cyanobacteria and one microalga belong to the genera Desmonostoc, Nostoc, Leptolyngbya, Chroococcidiopsis and Asterarcys. The relationships between substrates' specificity of these isolated biofilm organisms and those identified globally were evaluated using maximum parsimony analysis to generate a consensus phylogenetic tree. The five strains of cyanobacteria isolated were closely clustered with cyanobacteria belonging to a tropical region. At the generic level, no relationship between the species and substratum specificity was recorded. The exopolysaccharide analysis of the isolated strains revealed the presence of seven monosaccharides. While glucose was present in all the analysed species, the concentration of either fucose or arabinosewas high. The current study presents a novel HPTLC-based method for determination of monosaccharides composition from the extracellular polymeric substances.