E-Portfolio BMY3101 - Week 5

This week we were given a group task to choose a prokaryote and to make a presentation about the prokaryote. We had chose Serratia marcescens which is a motile,short rod-shaped, Gram-negative, facultative anaerobe bacterium, classified as an opportunistic pathogen. It was discovered in 1819 by Bartolomeo Bizio in Padua, Italy. Bizio named the genus Serratia in honor of and Italian physicist named Serratia, and chose marcescens for the species name after the Latin word for decay. 

S. marcescens was first thought to be harmless (non-pathogenic). Due to its ability to produce red pigmentation, it was first used in 1906 as a marker in order to trace bacterial activity or transmission. It was not until later in the 1950’s that the US government experimented with the S. marcescens and the harmful effects that the bacteria causes were revealed. A study using S. marcescens was carried out to determine the possibility of biological weapons being transmitted by wind current. 

S. marcescens is short and rod shaped. It is a facultative anaerobe, meaning that it can grow in either the presence of oxygen (aerobic) or in the absence of oxygen (anaerobic). Primarily it uses fermentation as the means of gathering energy and has enzymes (superoxide dismutase, catalase or peroxides) that protect it from reactive oxygen species, allowing it to live in oxygenated environments. S. marcescens is a gram negative bacterium. Gram negative bacteria have a thin cell wall made of a single layer of peptidoglycan that is enclosed by an outer membrane. The outer membrane has lipopolysaccharides (LPS), which are a special kind of phospholipid composed of fatty acids that are attached to a glucosamine phosphate dimer. S. marcescens is ubiquitous. It is commonly found in soil, water, plants and animals. It is widely present in non potable water in underdeveloped countries due to poor chlorination.

Picture of S. marcescens culture on agar plate surface