Bacteriovorax is a genus containing a single species of bacterium in the family Bacteriovoracaceae, Bacteriovorax stolpii. It is a predator that feeds on larger Gram-negative bacteria.[2] These prey bacteria tend to live in enteric environments and have similar lipopolysaccharide structures.[3]Bacteriovorax stolpii recognizes its prey by outer membrane protein receptors, which explains why Gram-positive bacteria that lack outer membranes do not serve as prey.[3] They prey on bacteria by invading the interperiplasmic space where they feed, grow, and reproduce.[3]Bacteriovorax stolpii used to be classified in the genus Bdellovibrio because of similar morphologies and lifestyle characteristics, however they were recognized as a new genus through phylogenetic analysis.[4]
The genera Bacteriovorax and Bdellovibrio share numerous morphological and lifestyle characteristics.[3]Bacteriovorax and similar genera are recognized by their presence of sphingolipids, which are not widely distributed in prokaryotes.[2]Bacteriovorax stolpii is known for the presence of sphinophosphonolipids in its membranes.[2] The genome size of the genus Bacteriovorax has been noted from 2.0–2.6 Mb.[3]Bacteriovorax is only predatory to Gram-negative bacteria, though they have been found in the gut of humans.[3]Bacteriovorax and Bdellovibrio are approximately 0.2-0.4 x 0.5-1.4 μm, are aerobic, with oxygen as a terminal electron acceptor, and are mesophilic.[3] They display a typical Gram-negative morphology and are motile by a single, polar, sheathed flagellum.[3]
History
The description of Bacteriovorax stolpii is based on the original description by Seidler et al.[5] Strain Uki2T is the only isolate described at this time and is the type strain of Bacteriovorax stolpii.[4] This isolate has a GC content of 41±8mol%.[5] The optimal temperature range for growth of this organism is 15–35°C. The major cellular fatty acids are 5:1ω8c13:0 and 13:0iso.[6] Uki2T is sensitive to most antibiotics tested (penicillin, streptomycin, neomycin, kanamycin, gentamicin, methicillin, nalidixic acid, pteridine 0/129 and vancomycin).[6]
Life cycle
Members of the Bacteriovorax exhibit the same general morphological and life cycle features as described for the genus Bdellovibrio.[3] In addition, members of this genus exhibit a biphasic life cycle, with the potential of displaying an actively predacious form as well as a PI (predatory independent), saprophytic form capable of growing on nutrient medium. Prey-dependent (wild-type) strains are comma-shaped rods, 0±5–1±4μm in length, which demonstrate a predatory lifestyle in the presence of susceptible prey bacteria. The wild-type strains are motile by a single, polar flagellum. PI cells (mutants) are pleomorphic, demonstrating a range of cell shapes from simple rods to long, tightly spiral shaped cells.[4]
Reclassification
Most bacteria that prey on Gram-negative bacteria were lumped together in the genus Bdellovibrio.[4] This was done regardless of their isolation from various habitats and unstudied phylogenetic relatedness.[4] The previously wide genus included differences in sodium chloride tolerance and %G+C content.[3]Bacteriovorax stolpii and Bacteriovorax starrii were compared to Bdellovibrio bacteriovorus, the model bacterium for its genus, using 16S rDNA sequences and analyses.[4] There was only 81.7% 16S rDNA sequence similarity between Bdellovibrio bacteriovorus and Bacteriovorax stolpii.[3] DNA-DNA hybridization also only yielded <4% hybridization between the species.[4] On these findings, the genus Bacteriovorax was created and Bacteriovorax stolpii and Bacteriovorax starrii moved into it.[4] In 2015, Bacteriovorax marinus and Bacteriovorax litoralis were reclassified as Halobacteriovorax, leaving B. stolpii as the only species in the genus.[7]
123Jayasimhulu, K.; Hunt, S.M.; Kaneshiro, E.S.; Watanabe, Y.; Giner, J-L. (2007). "Detection and Identification of Bacteriovorax stolpii UKi2 Sphingophosphonolipid Molecular Species". Journal of the American Society for Mass Spectrometry. 18 (3): 394–403. Bibcode:2007JASMS..18..394J. doi:10.1016/j.jasms.2006.10.014. PMID17123828.
1234567891011Bergey, D.H.; Brenner, D.J.; Krieg, N.R.; Staley, J.T. (2005). Bergey's Manual of Systematic Bacteriology. Volume 2. The Proteobacteria. Part C. The Alpha-, Beta-, Delta-, and Epsilonproteobacteria. New York, NY: Springer. pp.1053–7.
12Guether, D. L., Osterhout, G. J., Dick, J. D. & Williams, H. N. (1993). Analysis of fatty acid composition of Bdellovibrio isolates. Abstract Q-243 presented at the 93rd General Meeting of the American Society for Microbiology, Atlanta, Georgia, USA.
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