Serratia liquefaciens

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A Microbial Biorealm page on the genus Serratia liquefaciens

Classification

Higher order taxa [1]

Domain: Bacteria

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Enterobacteriales

Family: Enterbacteriaceae

Genus: Serratia

Species

NCBI: Taxonomy

Serratia liquefaciens

Description and significance

S. liquefaciens is a straight rod shaped bacterium with a diameter of 0.5-0.8 μm, a length of 0.9-2.0 μm, and Gram negative. Serratia species are usually motile and contain peritrichous flagella. [Bergey’s Manual of Determinative Bacteriology:9th edition p.187]

S. liquefaciens are facultative anaerobes making oxygen inessential to survival. They can inhabit both aerobic and anaerobic environments. Thus, S. liquefaciens is a widespread bacteria found in the environment and capable of colonizing on soil, water, plants, and the digestive tracts of rodents, insects, fish, and humans.[2] However, it must be noted that S. liquefaciens is not a normal component of human fecal flora. [3]

Not much is actually known about Serratia liquefaciens. In fact, up until 1971, it was actually characterized as Enterobacter liquefaciens. After extensive comparison with S. marcescens, E. liquefaciens was determined to be closely related to S. marcescens and the genus was changed to Serratia.[4]

Following the genus change, little can be found regarding S. liquefaciens. However, it has been proven to have certain antifungal properties in a plant’s rhizosphere. [5] It is also a pathogenic bacterium that has been associated with severe nosocomial infections. The Serratia genus as a whole is responsible for about 2% of nosocomial infections; most of which are attributed to S. marcescens. They tend to colonize in respiratory and urinary tracts of adults.[6]

Genome structure

Limited information can be found on the genome of Serratia liquefaciens. The entire genome has not been sequenced so the complete size and contents of the genome are unknown along with number of chromosomes. Several partial sequences of 16S ribosomal RNA have been analyzed and are indicated as linear strands.[7] [8] [9] However, the close relative S. marcescens has a single circular chromosome that is signature to many bacterial species. [10] It has also been proven that some bacteria may have multiple circular chromosomes or linear chromosomes and linear plasmids.[11]

Cell structure and metabolism

Serratia liquefaciens has a straight rod structure that is Gram negative. Gram negative organisms have a thinner layer of peptidoglycan surrounded by an inner and outer membrane. Serratia species are usually motile and have peritrichous flagella.

S. liquefaciens is able to ferment glucose and other carbohydrates (i.e. sucrose, D-mannose,D- mannitol, maltose, salicin, and trehalose) as a source of carbon while producing acid as a byproduct. S. liquefaciens also utilizes lysine, ornithine, and hydrolyzes gelatin, as a source of carbon and energy for growth. It can also hydrolyze DNA and reduce nitrate to nitrite –which may be a byproduct of anaerobic respiration and.[Bergey’s 217]

Ecology

Habitat; symbiosis; contributions to the environment.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Current Research and or Application to Biotechnology

Enter summaries of the most recent research and/or application to biotechnology here--at least three required

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Dr. Lynn M Bedard, DePauw University http://www.depauw.edu