Medium-chain-length polyhydroxyalkanoate production by newly isolated Pseudomonas sp. TN301 from a wide range of polyaromatic and monoaromatic hydrocarbons

Abstract

Aims: The aim of this study was to convert numerous polyaromatic and monoaromatic hydrocarbons into biodegradable polymer medium-chain-length polyhydroxyalkanoate (mcl-PHA). Methods and Results: Using naphthalene enrichment cultivation method, we have isolated seven bacterial strains from the river sediment exposed to petrochemical industry effluents. In addition to naphthalene, all seven strains could utilize between 12 and 17 different aromatic substrates, including toluene, benzene and biphenyl. Only one isolate that was identified as Pseudomonas sp. TN301 could accumulate mcl-PHA from naphthalene to 23% of cell dry weight. Owing to poor solubility, a method of supplying highly hydrophobic polyaromatic hydrocarbons to a culture medium was developed. The best biomass and mcl-PHA yields were achieved with the addition of synthetic surfactant Tween 80 (0·5 g l À1 ). We have shown that Pseudomonas sp. TN301 can accumulate mcl-PHA from a wide range of polyaromatic and monoaromatic hydrocarbons, and mixtures thereof, while it could also accumulate polyphosphates and was tolerant to the presence of heavy metal (100 mmol l À1 cadmium and 20 mmol l À1 nickel). Conclusions: A new Pseudomonas strain was isolated and identified with the ability to accumulate mcl-PHA from a variety of aromatic hydrocarbons. Significance and Impact of the Study: This study is the first report on the ability of a bacterial strain to convert a range of polyaromatic hydrocarbon compounds to the biodegradable polymer (mcl-PHA). Mcl-PHA is gaining importance as a promising biodegradable thermoelastomer, and therefore, isolation of new producing strains is highly significant. Furthermore, this strain has the ability to utilize a range of hydrocarbons, which often occur as mixtures and could potentially be employed in the recently described efforts to convert waste materials to PHA.

Bioconversion of Styrene to Poly(hydroxyalkanoate) (PHA) by the New Bacterial Strain <i>Pseudomonas putida</i> NBUS12

“…, 11 weeks) for a non-contaminated inoculum source, such as domestic activated sludge, was sufficient to yield styrene-degrading bacteria with mcl-PHA accumulation properties, providing a relatively simple and fast enrichment strategy. The mcl-PHA detected in all groups comprised C 6 , C 8 , C 10 , and C 12 monomers (Table 1), which was consistent with previous findings (25, 27). Previous studies suggested that the bioconversion process may begin with the side-chain oxidation of styrene and β -oxidation to form acetyl-CoA through phenylacetaldehyde before acetyl-CoA enters the downstream de novo fatty acid synthesis pathway that generates PHA precursors of varying chain lengths for PHA polymerization (29).…”

“…Aromatic-degrading and PHA-forming bacteria are generally isolated from petrochemical-contaminated sites or bioreactors treating petrochemical industrial effluents (13, 25, 26) because these pre-enriched sources are more likely to yield microorganisms that could break down petrochemical aromatics. In the present study, activated sludge from a water reclamation plant treating municipal wastewater and industrial activated sludge from a petrochemical wastewater treatment facility were tested as inoculum sources.…”

“…ADP, P. fulva TY16, P. putida F1, P. putida mt-2, Pseudomonas sp. TN301, and P. putida KT2440 (16, 21, 25, 26, 27, 30, 44) (Fig. 1A).…”

“…Only four styrene-degrading bacterial strains: Pseudomonas sp. TN301, P. putida CA-3 (NCIMB 41162), P. putida CA-1, and P. putida S12, have so far been shown to be capable of mcl-PHA accumulation (25, 42, 45). However, most of these bacteria accumulate PHA at low cellular contents of between 3 and 14% cell dry mass (% CDM).…”

Biotransformation of aromatic hydrocarbon: Naphthalene to Aliphatic Hydrocarbons through Staphylococcus pasteuri RD2

“…3) Narancic et al, (2012) reported the conversion of a range of polyaromatic hydrocarbon compounds to medium chain length PHA. The bacterial strain Pseudomonas sp.…”