Scaling-up the production of recombinant Moringa oleifera coagulant protein for large-scale water treatment applications

Abstract

Provision of safe drinking water, devoid of aetiologies is an all-time challenge due to the usage of unsafe chemicals in most of the water treatment processes. In this regard, proteins of Moringa oleifera (MO) provide most promising solutions, as its crude seed extracts are being used as natural ‘water clarifiers’ in drinking and wastewater treatments. Among MO seed proteins, a 6.5 kDa coagulant protein (MO coagulant protein; MOCP) has gained importance because of its antimicrobial and water clarification properties. Considering the biomedical and commercial values of the MO plant, in this study, the cDNA coding for MOCP was cloned and over expressed in E. coli BL21 (DE3). After bench-scale experiments, for the first time, the recombinant protein production was scaled up to 7 L bioreactors in Luria Broth supplemented with 1% glucose. About 42 mg of Moringa oleifera coagulating recombinant protein (MOCRP; 6.5 kDa) was purified using superparamagnetic iron oxide nanoparticles (SPION) from 1 litre of the over expressed E. coli cell cultures. The purified MOCRP revealed an efficient coagulation activity (∼66%) even with 0.1 mg L⁻¹; while very good antimicrobial response was recorded against a set of Gram-negative and Gram-positive microorganisms at as low as 10 mg L⁻¹. Thus, we report the over expression and purification of this dual-function protein (MOCRP) from moringa for the first time, using bioreactors with an economical and user-friendly approach for large-scale applications.