Production of thermostable protease enzyme in wastewater sludge using thermophilic bacterial strains isolated from sludge

Abstract

Abstract:The volume of sludge produced annually is very high and poses serious disposal problems. The traditional methods of sludge disposal produce secondary pollutants. Therefore, the alternate or suitable solution is reuse of sludge in an ecofriendly approach. Biotechnology is an interesting tool to add value to the processes involved in wastewater and wastewater sludge disposal/reuse. In this context, a study was carried out on thermophilic bacterial strains that produce thermostable proteases. The bacterial strains were first isolated from municipal wastewater sludge. In contrast to the conventional strains used in industries, like Bacillus sp., the new strains were Gram-Negative type. In semi-synthetic medium, a maximal protease activity of 5.25 IU/ml (International Unit per ml) was obtained at a pH of 8.2 and at a temperature of 60 o C, which is higher than the stability temperature of 37°C for a similar protease obtained from the conventional producer Bacillus licheniformis. Moreover, growth and protease activity of the strains were tested in wastewater sludge. It is expected that the complexity of sludge could stimulate/enhance the protease production and their characteristics. In conclusion, reuse of wastewater sludge will help to reduce their quantity as well as the value-added products produced will replace chemical products used in industries.Keywords: Thermophilic strains; thermostable proteases; wastewater sludge INTRODUCTIONThe disposal of wastewater sludge (WWS) generated during the treatment of the various municipal and industrial wastewater (WW) is one of the major problems in safeguarding of the planetary environment. During the last fifty years, people believed that the discharge of WW and WWS in the rivers and the lakes was not detrimental to the environment because the latter had the capacity to self purify and regenerate themselves. However, studies during the last twenty years have contradicted these facts. At the present time, the rivers and the lakes do not have the capacity to absorb all the pollutants which are poured there (Barnabé and et al., 2003). It thus became imperative to find new methods in order to decrease and/or re-use these wastes. Several of these new methods have been developed in recent past and others are being developed.

Screening and isolation of protease-producing bacteria from wastewater samples in Obafemi Awolowo University (OAU) Campus, Ile-Ife, Nigeria

“…possess the potential for alkaline protease production. This highlights the viability of utilizing wastewater as a source for isolating bacteria with protease production capabilities, specifically Bacillus spp, which have demonstrated success in alkaline protease production in related studies (Haile & Babiye, 2018;Haider & Sanaa, 2014;Chenel et al, 2008;Tyagi et al, 2002).…”

Green Biotechnology for Municipal and Industrial Wastewater Treatment

“…Fermentation experiments were conducted in a bioreactor equipped with accessories and automatic control systems for dissolved oxygen (above 20% of saturation), pH (7.0, controlled automatically by using 2N NaOH or 2N H 2 S0 4 ), antifoam, agitation speed (300-500 rpm), aeration rate and temperature (50°C) for 48 hours [55]. The bacterial strains were first isolated from municipal wastewater sludge.…”

Enzymatic Proteolysis of a Surface-Bound α-Helical Polypeptide

“…Enzyme production in 1982 was $375 million, up to $720 million in 1990, $1 billion in 1994, $1.9 billion in 1996, $2.5 billion in 2001, and approximately $2.8 billion in 2002. , Bacterial alkaline proteases accounted for approximately 35% of the total industrial enzyme market . Market projections show that, in the U.S. enzyme market alone, demand will grow by 6.9% annually through 2010, with both proteases and carbohydrases expected to continue to dominate market growth and demand…”