Valorization of dairy effluent for the conversion of microbial fibrinolytic enzymes for environment management and bio-medical applications

Enhanced fibrinolytic enzyme production was achieved by process optimization using Stenotrophomonas maltophilia AD 143 in submerged fermentation. Dairy wastewater was used as the low-cost medium. The selected bacterial strain synthesized enzymes at wide pH (7.5–8.5) and temperature ranges (35–55 °C). Scale-up experiments were carried out in a 10-L benchtop fermenter with optimum air flow (4.0 L/min). The fibrinolytic enzyme was purified by a combination of solvent extraction, gel filtration chromatography and affinity chromatography. The molecular mass of the fibrinolytic enzyme was estimated to be 31.8 kDa by SDS-PAGE. The purified enzyme showed high activity at pH 8.0 and at 45 °C. It could digest various natural proteins, such as feather meal, casein, fibrin, and human hair and could elicit blood clot-lytic activity. The screened S. maltophilia AD 143 is useful for the conversion of dairy effluent into fibrinolytic enzymes for waste management. The purified fibrinolytic enzyme showed specificity to fibrin substrates and may have potential applications in the treatment of cardiovascular diseases.