Question

1. In a phosphate limitation environment, E. coli will be induced to produce alkaline phosphatase.

(A) What is the function of alkaline phosphatase? And how does it help the bacteria to survive in this environment?

(B) The phosphate sensing system of E. coli is an example of sensor kinase system. Describe the molecular mechanism of the phosphate sensing system of E. coli using the sensor kinase model.

2. Pseudomonas aeruginosa is used as a bacterial model to study biofilm mechanism. In order to develop a mature biofilm structure, the bacteria have to form a micro-colony first. Explain this phenomenon by using the Quorum sensing mechanism.

Answer 1

1.A.Alkaline phosphatase is found in the periplasmic space of E. coli bacteria. This enzyme is heat stable and has its maximum activity at high pH. In humans, it is found in many forms depending on its origin within the body – it plays an integral role in metabolism within the liver and development within the skeleton.

ALP has the physiological role of dephosphorylating compounds. The enzyme is found across a multitude of organisms, prokaryotes and eukaryotes alike, with the same general function but in different structural forms suitable to the environment they function in.

B.Two-component systems comprising sensor histidine kinases and response regulator proteins are among the most important players in bacterial and archaeal signal transduction and also occur in reduced numbers in some eukaryotic organisms. There is significant diversity in the mechanisms employed by individual systems. This review discusses the current knowledge on common themes and divergences from the paradigm of two-component system signaling. An emphasis is on the information gained by a flurry of recent structural and bioinformatics studies.

2.In living organisms, biofilms are defined as complex communities of bacteria residing within an exopolysaccharide matrix that adheres to a surface. In the clinic, they are typically the cause of chronic, nosocomial, and medical device-related infections. Due to the antibiotic-resistant nature of biofilms, the use of antibiotics alone is ineffective for treating biofilm-related infections. In this review, we present a brief overview of concepts of bacterial biofilm formation, and current state-of-the-art therapeutic approaches for preventing and treating biofilms. Also, we have reviewed the prevalence of such infections on medical devices and discussed the future challenges that need to be overcome in order to successfully treat biofilms using the novel technologies being developed.