Methylibium petroleiphilum

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A Microbial Biorealm page on the genus Methylibium petroleiphilum

Classification

Higher order taxa

A Microbial Biorealm page on the genus Methylibium petroleiphilum

Classification

Higher order taxa

Kingdom: Bacteria Phylum: Proteobacteria Class: Betaproteobacteria Order: Burkholderiales Family: Comamonadaceae Genus: Methylibium Species: petroleiphilum Strain: PM1 (extensively studied and all available data on) (1)

Species

petroleiphilum Genus species

Methylibium petroliphilum

Description and significance

Methylibium petroleiphilum PM1 was first discovered in 1998 by Professor Kate Scow at UC Davis when purifying biofilters used for treating byproducts from oil refineries. The specific PM1 strain of the bacteria was isolated from a culture enriched with methyl tert-butyl ether (MTBE) from a biofilter from the Los Angeles County Joint Water Pollution Control Plant. (2)

The discovery of M. petroleiphilum PM1 was significant in that it was determined to be the first and currently only known species of bacteria capable of using MTBE as a sole source of carbon. The fact that MTBE is the sole carbon source is a key property of M. petroleiphilum PM1 which makes is a great candidate for bioremediation. (3) Starting in the last 15 years, oil refineries began using MTBE in oil and petroleum purification. MTBE however, is a carcinogen which on numerous occasions has entered water systems and caused massive contaminations. The detection of M. petroleiphilum PM1 in contaminated water supplies could be indicative that it plays a role in purifying the water supply. (4)

16S rRNA sequence analysis revealed that M. petroleiphilum PM1 was a novel genus with 93-96% similarities to the genera Leptothrix, Aquabacterium, Roseateles, Sphaerotilus, Idenella, and Rubrivivax. (5)

To date, M. petroleiphilum PM1has been discovered in a vast number of MTBE contaminated water supplies such as the US, Mexico, and Europe and it is assumed that M. petroleiphilum PM1 is abundantly found in any other MTBE tainted water supply in other parts of the world. (6)

M. petroleiphilum PM1is not known to be pathogenic. (6)

Genome structure

M. petroleiphilum PM1 has a 4,044,225 nucleotide (approximately 4Mb) circular chromosome and a 599,444 nucleotide (approximately 600kb) megaplasmid. The chromosome and megaplasmid contain 3,831 and 646 genes respectively. The G+C content of the chromosome and plasmid are 69.2% and 66% respectively; this suggests that the DNA has a relatively high melting temperature and is perhaps an adaptation to harsh environments that may cause irregular annealing. (5)

Genes of that encode enzymes that degrade and catabolize aromatic compounds and alkanes, pumps to uptake and expel metals (metal resistance), and methylotrophy are primarily found in the circular chromosome. (7)

The megaplasmid also encodes genes for alkane degradation and MTBE degradation and metabolism. Also, noted was that the plasmid contains some anomalies unlike plasmids in other bacteria such as t-RNA islands (some of which do not have a valid anti-codon sequence), irregular insertions, and an unusually large number of repeated elements and genes such as a 40 kb region identical to the chromosome as well as a smaller 29 kb region identical to the chromosome. Comparative genome hybridization experiments provide compelling evidence that M. petroleiphilum PM1 acquired its plasmid recently and also that the megaplasmid is what may contain the most critical genes involved in MTBE degradation and metabolism. Another interesting attribute of M. petroleiphilum PM1 is that varying isolates of the identical strain show approximately 99% conservation of the megaplasmid but chromosomal similarities were of a much lower order of magnitude. (7)

Cell structure and metabolism

M. petroleiphilum PM1 is a Gram-negative, motile bacteria with a rod shape and is non-pigmented, aerobic bacteria. The rod structure of the bacteria can range in size from 0.5-2.0 μM. The rods also do not contain any sheaths. Motility is achieved by the use of a polar flagellum. Reproduction occurs by generic binary fission. The fatty acids that make up the majority of the plasma membrane are composed of C16:1w7c and C16:0. (7)

An attribute that M. petroleiphilum PM1 shares with members of the Sphaerotilus-Leptothrix group is the presence of intracellular granules of poly-β-hydroxybutyrate. In addition, M. petroleiphilum PM1 has a cell morphology characteristic of the genus Aquabacterium with the exception of lacking a fibrillar matrix. (7)

M. petroleiphilum PM1is characterized as a methanotroph since it can use methane as a carbon source; however, M. petroleiphilum PM1 lacks all intracellular structures which normally characterize methanotrophs. (7)

Under optimal growth conditions, the bacteria can form cream color flat colonies with smooth features ranging from 2-3 mm in diameter. When grown under very basic conditions, the colonies maintain the same size and shape however tend to be white. Lack of pigmentation (such as orange or pink) is another unusual attribute of M. petroleiphilum PM1 that other methanotrophs poses. (7)

For proper metabolism, M. petroleiphilum PM1does not require any vitamins or other organic nutrients and can derive all organic compounds from MTBE. The bacterium however does require the trace elements cobalt, copper, manganese, zinc, molybdenum, nickel, and iron. This strain also can metabolize and make use of other organic carbohydrates and amino acids as nutrient sources such as pyruvate, ethanol, L-aspargine, acetate, butanol, methanol, toluene, benzene, phenol, ethylbenzene, 3,4-dihydroxybenzoate, 2,5-dihydroxbenzoate, 3,5-dihydroxbenzoate, 2,6-dihydroxbenzoate and 2,3-dihydroxbenzoate. Unlike other methanotrophs, M. petroleiphilum PM1 has a wide variety of substrates to derive nutrients from. (7)

M. petroleiphilum PM1grows optimally at pH 6.5 and around 30 degrees Celsius. (7)

Ecology

M. petroleiphilum PM1is found primarily in sites contaminated with MTBE as well as other aromatic hydrocarbon contaminated sites. The bacteria play a role in what appears to be a form of bioremediation by breaking down the hazardous compounds. (4). It is intuitive to think that both the environment and bacteria benefit since the bacteria have an abundant food supply of hydrocarbons such as MTBE and they clean the environment at the same time. Grows well in aerobic, warm, and close to neutral pH conditions. (7)

Pathology

M. petroleiphilum PM1 is not known to be pathogenic. (7)

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research 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 Rachel Larsen

Species

NCBI: Taxonomy

Genus species

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

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

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research 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 Rachel Larsen