Diversity, molecular phylogeny, and metabolic activity of cyanobacteria in biological soil crusts from Santiniketan (India) Dhanesh Kumar & Siba Prasad Adhikary Received: 11 December 2013 /Revised and accepted: 24 April 2014 # Springer Science+Business Media Dordrecht 2014 Abstract The biological soil crusts that appear on the arid soils of Santiniketan, India soon after receiving monsoon rain were studied. The phototrophic organisms in the crusts were principally composed of sheath-forming cyanobacteria be- longing to the genera Scytonema and Tolypothrix as the major components along with associated species of 14 different genera. 16S ribosomal RNA (rRNA) sequencing of these organisms showed that they formed a cluster quite different from Leptolyngbya, Microcoleus, and Phormidium, however, were close to Scytonema and Tolypothrix reported from similar biofilms on soils of USA and Costa Rica. All these major cyanobacteria species in soil crust possessed scytonemin in higher proportion than chlorophyll a, suggest- ing its role in protection from high solar irradiance and UV. Dried crusts started respiring soon after wetting followed by photosynthesis. Nitrogenase activity also revived after 2 to 12 h of wetting and progressed rapidly with longer period of wet conditions coinciding with appearance of heterocysts in the filaments. These results showed that a number of cyanobacteria with distinct sheath layer survived within the soil crusts in desiccated state and revived their metabolic activity soon after receiving monsoon rain thus contributing to carbon as well as nitrogen fixation in the environment and to nutrient mobilization making the soil productive. Keywords Biological soil crusts . Cyanobacteria . Molecular phylogeny . Rewetting . Metabolic activity Introduction Biological soil crusts (BSCs) occur on the topmost layer of the soil (Belnap 2003). They appear crusty on the exposed surface of soils in India soon after receiving water on the onset of monsoon rain. They are composed of a variety of microor- ganisms, e.g., cyanobacteria, green algae, lichens, mosses, microfungi, and other bacteria in different proportions (Belnap and Lange 2001). The photoautotrophic organisms fix carbon in the presence of sunlight, colonize soil surface, and live utilizing available nutrients in the substratum. BSCs principally containing cyanobacteria have been recorded from all biomes in almost all continents covering North America (Rosentreter and Belnap 2001), South America (Büdel 2001a), Europe and Mediterranean region (Büdel 2001b), Arctic Greenland (Hansen 2001), Alps (Türk and Gärtner 2001), Middle East (Galun and Garty 2001), Africa (Ullmann and Büdel 2001; Büdel et al. 2009), Australia (Eldridge 2001), Antarctica (Green and Broady 2001), China (Hu et al. 2003; Zheng et al. 2011), and India (Tirkey and Adhikary 2005, 2006). Most of these organisms possess a well-defined sheath around their trichome and/or copious mucilage which increases soil stability by binding soil parti- cles together, protecting from wind and water erosion (Belnap and Gillette 1998, Zhang et al. 2011). BSCs containing or- ganisms with polymeric matrix of polysaccharides have been reported to influence the soil texture, pore formation, and water retention, which in term determine biological activity in arid lands (Rossi et al. 2012). Also, many of these organ- isms, being nitrogen fixers, contribute nitrogen to the soil along with carbon, thus playing an important role in mobili- zation of nutrients in almost all types of soil ecosystems (Belnap et al. 2001; Elbert et al. 2012). Not much information is available on BSCs of Indian subcontinent with a tropical climatic regime, where varying type of soils, ranging from desert in the west to the Alpine in Himalayas along with moist D. Kumar : S. P. Adhikary Department of Biotechnology, Institute of Science, Visva-Bharati, Santiniketan, West Bengal 731235, India D. Kumar (*) Faculty of Food and Biochemical Technology, Institute of Chemical Technology, Dejvice, Praha-6, Czech Republic e-mail: dhanesh7bt@gmail.com J Appl Phycol DOI 10.1007/s10811-014-0328-0