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[Free proteolytic activity from Serratia marcescens. II. Kinetics of production and mechanism of induction]
R Hernández-Delgadillo1, J J Ruiz-Cruz
1Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, México, D.F., México.
Abstract:
This paper shows that Serratia marcescens WF yields free proteolytic activity partially associated to growth, i.e. when the maximal rate of growth is reached, when it was growing in a saline medium supplemented with casein peptone. When the culture medium was utilized for a second time after it was used up (exhausted medium), growth and yield of free proteolytic activity showed the same partial association. With a protein medium containing peptides from 1000 to 5000 of molecular weight, from casein peptone, growth and yield of free proteolytic activity were partially associated too. In this paper, we demonstrated that Serratia marcescens WF yields free proteolytic activity only when growth rate is decelerating and under no growth conditions. We also demonstrated than the inducer structure acts gratuitously, because it cannot be used like a carbon and/or energy source. The structural form of the true inducer remains to be established. Finally, we propose that when growth rate is decelerating, or under no growth conditions, Serratia marcescens WF yields free proteolytic activity to obtain nitrogen from protein sources, apparently as the only function.
Insights
Serratia marcescens WF produces proteolytic enzymes when its growth rate slows or stops, primarily to acquire nitrogen from proteins. This enzyme production is independent of its use as a nutrient source.
Area of Science:
- Microbiology
- Biochemistry
Context:
- Investigating the production of extracellular enzymes in bacteria.
- Understanding the regulation of proteolytic activity in Serratia marcescens.
Purpose:
- To determine the conditions under which Serratia marcescens WF produces free proteolytic activity.
- To elucidate the role of growth rate and nutrient availability in enzyme induction.
Summary:
- Serratia marcescens WF exhibits maximal free proteolytic activity during decelerating growth phases and under non-growth conditions.
- The enzyme production is induced by specific protein structures that do not serve as carbon or energy sources.
- Proteolytic activity is proposed to function primarily in nitrogen acquisition from protein sources.
Impact:
- Provides insights into bacterial adaptation and nutrient scavenging strategies.
- Contributes to the understanding of microbial enzyme regulation.
- Potential implications for biotechnological applications involving protease production.