KINETIC PARAMETERS OF PROTEASE ACTIVITY OF PEPTOSTREPTOCOCCUS SP. AS A TOOL FOR REGULATION OF DAIRY WASTEWATER TREATMENT

I. Schneider, Y. Topalova

Abstract: The protein biodegradation is one of rate-limiting processes during dairy wastewater treatment. An opportunity for process acceleration is addition of microbial cultures with high protease activity or addition of pure proteases. In this regard, protein degrading bacteria Peptostreptococcus sp. was isolated during an anaerobic wastewater treatment process for dairy industry with the goal of developing an inoculum for bioaugmentation strategy. The goal of this paper was purposely investigation of the key kinetic parameters of the protease activity of Peptostreptococcus sp. that are critical for regulation of protein biodegradation in dairy effl uent treatment – temperature, pH, substrate concentration, cationic modulators. A batch process, with mineral medium, casein as sole carbon source and Peptostreptococcus sp. as microbial biodegradant, was simulated in lab scale. The obtained results show that protease activity from Peptostreptococcus sp. was increased after 72nd hour of the cultivation process and the specifi c rate of biodegradation was 0.025 g.l–1.h–1.mg Protein–1. A Michaelis – Menten plot analysis indicated that Km value of protease activity is 0.5 μM and Vmax is 8.624 μM Tyrosine.min–1.mg–1Protein. The optimal conditions for protease activity were at temperature 55oC and at pH 8.00. The divalent magnesium ions in concentration 1, 10, 25, 50 and 100 mM were positive modulator of protease activity while divalent calcium ions in these concentrations were inhibitor. The obtained results discovered possibilities for regulation of wastewater treatment process with the key microbial factor Peptostreptococcus
sp. The further investigations will be directed to elucidate of information how to increase the amount and activity of Peptostreptococcus sp. in activated sludge and biofilm in real dairy wastewater treatment technologies.

Keywords: bioaugmentation; casein biodegradation; modulation effect; protease kinetics

Date published: 2017-10-19