Reduction in unit weight of concrete with no compromise on the strength will lead to economy in the size of the structural members. Bacillus subtilis bacteria is cultured and used in this investigation for its calcite formation property. 20% of fine aggregate is replaced by Light weight clay aggregate (LECA)in this investigation. Compressive strength of bacterial concrete increased to 28%, 39.5% and 52.17% with 16ml, 32ml and 48ml of bacteria. 20% of replacement of fine aggregate by LECA lead to an increase in the compressive strength of light weight bacterial concrete 14.93%, 13.827% and 6% with the inclusion of 16ml, 32ml, 48ml of bacteria of bacterial solution.