A novel hot spring bacterial strain was isolated and characterized from Bakreshwar, West Bengal, India. Phylogenetic analysis of partial 16 S-rRNA gene sequence (697 nucleotides) suggested that the isolate was affiliated with the family 'Firmicutes' and 99.8% homologous with Thermoanaerobactor thermohydrosulfuricus. A unique thermostable and high pH tolerant protein (28 kDa) secreted by the bacterium was isolated whose N-terminal partial sequence (25 AA) suggested that the protein was similar to mammalian carbonic anhydrase-II. This bacterium or its unique protein both increase the compressive (>25%) and tensile (>20%) strengths, hardness and elastic modulus of cementitious material when incorporated to the cement/cement-sand mixture. The protein (named as bioremediase) possesses silica leaching activity, which is increased by calcium ions. No esterase and/or proteolytic activities are present in the protein. The use of such isolated bacterium or its protein in concrete technology develops new construction material that may be used for self-healing concrete in future. (C) 2010 Elsevier Inc. All rights reserved.