Parvibaculum lavamentivorans

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Scanning electron micrograph of P. lavamentivorans DS-1^T.

Classification

Higher order taxa

Bacteria; Proteobacteria; Alphaproteobacteria; Rhizobiales; Rhodobiaceae

Species

Parvibaculum lavamentivorans

Description and Significance

Parvibaculum lavamentivorans DS-1^T is a slightly curved rod shaped, motile, gram-negative, non-pigmented, aerobic, chemoorganoheterotrophic bacterium that cabe be motile by means of a polar flagellum. P. lavamentivorans readily form biofilms. The species does not sporulate. Individuals are about 1.0 × 0.2 μm. The bacterium is positive for catalase activity but negative for oxidase activity. Colonies are smooth, white to non-pigmented, slightly raised in the centre and have regular edges that are 1–2 mm in diameter. The species is environmentally significant for its ability to catalyze the degradation of laundry detergents. When utilizing commercial LAS, this species requires a biofilm on a solid surface for growth. Parvibaculum lavamentivorans degrades commercial LAS via omega-oxygenation, oxidation and chain shortening through b-oxidation to yield a wide range of sulphophenylcarboxylates (SPCs). The SPCs are then degraded in bacterial communities which contain organisms like P. lavamentivorans.

Genome Structure

The genome of Parvibaculum lavamentivorans is completely sequenced for representative strain DS-1^T.[1] The DNA is packaged into one circular chromosome which contains one origin of replication, 3.91Mb, 3715 genes and 3648 coding genes with 62.3%GC. Around 200 genes are estimated to be directly involved in alkyl-chain degradation. The bacterial immune repsonse CRISPR sequence is presenet. The genome contains only one rRNA operon, which is indicative of slow growth.

Cell Structure, Metabolism and Life Cycle

Parvibaculum lavamentivorans is a mesophile which grows optimally at 30ºC. P. lavamentivorans tolerates NaCl concentrations of 0-3%. It is capable of using acetate, ethanol, pyruvate, succinate, alkanes (C8 – C16), and various anionic and non-ionic surfactants as a carbon source. Oxygen is the final electron acceptor. The organism is capable of performing the citrate cycle, glycolysis/gluconeogenesis, and the non-oxidative pentose-phosphate pathway. This bacterium degrade alkanes and surfactants through the abstraction of acetyl-CoA. The genome consists of multiple genes for the the initiation of the alkyl-chain degradation.

Ecology

Parvibaculum lavamentivorans is capable of degrading 17 commercially important surfactants including linear alkylbenzenesulfonate (LAS). 2.5 million tons of LAS waste are produced each year. P. lavamentivorans degrades surfactants like LAS and releases short chain intermediates which are further degraded by local microbes. Parvibaculum species are frequently detected by cultivation-independent methods, predominantly in habitats or settings with hydrocarbon degradation. These include a bacterial community on marine rocks polluted with diesel oil, a bacterial community from diesel-contaminated soil, a petroleum-degrading bacterial community from seawater, an oil-degrading cyanobacterial community and biofilm communities in pipes of a district heating system. Parvibaculum species have also been detected in denitrifying, linear-nonylphenol degrading enrichment cultures from NP-polluted river sediment and in groundwater that had been contaminated by linear alkyl benzenes. Additionally, Parvibaculum species were detected in biofilms that degraded polychlorinated biphenyls (PCBs) using pristine soil as inoculum, and in a PAH-degrading bacterial community from deep-sea sediment of the West Pacific. Finally, Parvibaculum species were detected in an autotrophic Fe(II)-oxidizing, nitrate-reducing enrichment culture, as well as in Tunisian geothermal springs. The widespread occurrence of Parvibaculum species in habitats or settings related to hydrocarbon degradation implies an important function and role of these organisms in environmental biodegradation, despite their attribute as being difficult to cultivate in a laboratory