Thermostable alkaline β-lactamase isolation and purification from thermophilic bacterial strain Geobacillus stearothermophilus “AAP7919”

β-Lactam antibiotic resistance has been a big problem since the usage of these antibiotic drugs in medical practice. For reducing the side-effects of these antibiotics, the β-lactam antibiotic degrading enzymes play a major role. A thermophilic bacterial strain Geobacillus stearothermophilus “AAP7919” (NCBI accession number GU459259) isolated from oil sludge site, was found capable of producing of β-lactamase enzyme in alkaline condition (pH 10) with Benzyl-penicillin as substrate. In the present study an attempt was made to characterize and optimize the production of this enzyme by ion exchange chromatographic purification followed by SDS - PAGE and FTIR studies. Primarily the enzyme activities of extracellular and intracellular β-lactamase were detected as 33.15 U mg⁻¹ and 15.56 U mg⁻¹ respectively. The optimal production of β-lactamase was determined at pH 10.0 (828.73 U mg⁻¹) at 40°C temperature and the maximum thermal stability period with enzyme activity 563.54 U mg⁻¹ was observed at 210 min (50°C). The main functional groups which are involved in IR adsorption process were found to be alcohols, alkenes and alkyl halides. The broad intense absorption peaks at 3436 cm⁻¹ indicated the existence of alcohol groups. The peaks located at 1135 cm⁻¹, 1054 cm⁻¹ and 711 cm⁻¹ were characteristics of alkyl halide groups. The peaks located at 1633 cm⁻¹, 997 cm⁻¹ and 923 cm⁻¹ were characteristics of alkenes groups. The peaks at 2083 cm and 1405 cm were characteristics of alkynes and aromatic groups respectively