ISOLATION AND IDENTIFICATION OF CALCITE FORMING BACTERIA FROM SOIL AND LIMESTONE COLLECTED IN BA RIA VUNG TAU PROVINCE

Abstract

Calcite-forming by bacteria has been reported in various geological environments including limestone caves, and soil. There are four natural processes by which calcite is formed: carbonic anhydrase (CA), sulfate reduction, nitrate reduction, and urea hydrolysis. The study aims to identify calcite-forming bacteria occurring in limestone areas of Ba Ria Vung Tau province. 128 bacterial strains were obtained on B4 agar. Nine strains (BRVT1, BRVT2, BRVT3, BRVT4, BRVT5, BRVT6, BRVT7, BRVT8, and BRVT9) were selected by seemingly determining high calcite production and urease activity. Among the bacterial isolates, the BRVT1 strain produced is 11.8 g/L calcite precipitate; BRVT2, the BRVT5 strains are 11.4 g/L, and the BRVT4 strain is 12.8 g/L. The 16S rRNA gene sequencing identified isolates as BRVT1 strain is Bacillus tequilensis, BRVT2 and BRVT5 strain are Bacillus cereus and BRVT4 strain is Bacillus subtilis. Further, the microstructure of calcite precipitated was inspected through scanning electron microscopy (SEM), and X-ray diffraction (XRD).