Enterobacter aerogenes

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Enterobacter aerogenes
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gamma Proteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Enterobacter
Binomial name
Enterobacter aerogenes
Lab Findings
Shape rods
Hemolysis -
Catalase +
Citrate +

Enterobacter aerogenes is a Gram-negative, oxidase negative, catalase positive, citrate positive, indole negative, rod-shaped bacterium.[1] The bacteria is approximately 1-3 microns in length, and are capable of motility via peritrichous flagella.[2]

E. aerogenes is a nosocomial and pathogenic bacterium that causes opportunistic infections including most types of infections. The majority are sensitive to most antibiotics designed for this bacteria class, but this is complicated by their inducible resistance mechanisms, particularly lactamase, which means that they quickly become resistant to standard antibiotics during treatment, requiring a change in antibiotic to avoid worsening of the sepsis.

Some of the infections caused by E. aerogenes result from specific antibiotic treatments, venous catheter insertions, and/or surgical procedures. E. aerogenes is generally found in the human gastrointestinal tract and does not generally cause disease in healthy individuals. It has been found to live in various wastes, hygienic chemicals, and soil. The bacterium also has some commercial significance – the hydrogen gas produced during fermentation has been experimented with using molasses as the substrate.

E. aerogenes is an outstanding hydrogen producer. It is an anaerobic facultative and mesophilic bacterium that is able to consume different sugars and in contrast to cultivation of strict anaerobes, no special operation is required to remove all oxygen from the fermenter. E. aerogenes has a short doubling time and high hydrogen productivity and evolution rate. Furthermore, hydrogen production by this bacterium is not inhibited at high hydrogen partial pressures; however, its yield is lower compared to strict anaerobes like Clostridia. A theoretical maximum of 4 mol H2/mol glucose can be produced by strict anaerobic bacteria. Facultative anaerobic bacteria such as E. aerogenes have a theoretical maximum yield of 2 mol H2/mol glucose.[3]

It may spoil maple sap and syrup.[4]

Biochemical identification test results[5][edit]

Identification Method Test Result
Mobility Positive
Indole Negative
Methyl Red Negative
VP Positive
Citrate (Simmons) Positive
Nitrate Reduction Positive
Hydrogen Sulfide (TSI) Negative
Urea Hydrolysis Negative
Oxidase Negative
Phenylalanine Deaminase Negative
Eosin-methylene blue Positive
Glucose Fermentation Acid/Gas
Lactose Fermentation Acid/Gas
Sucrose Fermentation Acid/Gas
Mannitol Fermentation Acid/Gas
Growth in KCN Positive
Ornithinine Decarboxylase Positive
Gelatin Hydrolysis (22oC) Negative


  1. ^ Sanders WE, Sanders CC (1997). "Enterobacter spp.: pathogens poised to flourish at the turn of the century". Clin. Microbiol. Rev. 10 (2): 220–41. PMC 172917Freely accessible. PMID 9105752. 
  2. ^ "Morphological Characteristics of Enterobacter aerogenes". 
  3. ^ Asadi, Nooshin; Zilouei, Hamid (March 2017). "Optimization of organosolv pretreatment of rice straw for enhanced biohydrogen production using Enterobacter aerogenes". Bioresource Technology. 227: 335–344. doi:10.1016/j.biortech.2016.12.073. 
  4. ^ MICROBES INVOLVED IN FOOD SPOILAGE Authors: Gabriel Chavarria, Julia Neal, Parul Shah, Katrina Pierzchala, Bryant Conger
  5. ^ Farmer, J J; Davis, B R; Hickman-Brenner, F W; McWhorter, A; Huntley-Carter, G P; Asbury, M A; Riddle, C; Wathen-Grady, H G; Elias, C (1985-01-01). "Biochemical identification of new species and biogroups of Enterobacteriaceae isolated from clinical specimens.". Journal of Clinical Microbiology. 21 (1): 46–76. ISSN 0095-1137. PMC 271578Freely accessible. PMID 3881471. 

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