A Gram-negative bacterium, identified as Pseudomonas aeruginosa AL98, is a potent degrader of natural rubber and synthetic cis-1,4-polyisoprene

An aerobic enrichment culture was developed by using vinyl chloride (VC) as the sole organic carbon and electron donor source. VC concentrations as high as 7.3 mM were biodegraded without apparent inhibition. VC use did not occur when nitrate was provided as the electron acceptor. A gram-negative, rod-shaped, motile isolate was obtained from the enrichment culture and identified based on biochemical characteristics and the sequence of its 16S rRNA gene as Pseudomonas aeruginosa, designated strain MF1. The observed yield of MF1 when it was grown on VC was 0.20 mg of total suspended solids (TSS)/mg of VC. Ethene, acetate, glyoxylate, and glycolate also served as growth substrates, while ethane, chloroacetate, glycolaldehyde, and phenol did not. Stoichiometric release of chloride and minimal accumulation of soluble metabolites following VC consumption indicated that the predominant fate for VC is mineralization and incorporation into cell material. MF1 resumed consumption of VC after at least 24 days when none was provided, unlike various mycobacteria that lost their VC-degrading ability after brief periods in the absence of VC. When deprived of oxygen for 2.5 days, MF1 did not regain the ability to grow on VC, and a portion of the VC was transformed into VC-epoxide. Acetylene inhibited VC consumption by MF1, suggesting the involvement of a monooxygenase in the initial step of VC metabolism. The maximum specific VC utilization rate for MF1 was 0.41 mol of VC/mg of TSS/day, the maximum specific growth rate was 0.0048/day, and the Monod half-saturation coefficient was 0.26 M. A higher yield and faster kinetics occurred when MF1 grew on ethene. When grown on ethene, MF1 was able to switch to VC as a substrate without a lag. It therefore appears feasible to grow MF1 on a nontoxic substrate and then apply it to environments that do not exhibit a capacity for aerobic biodegradation of VC.Contamination of groundwater with vinyl chloride (VC) occurs primarily via anaerobic reductive dechlorination of tetrachloroethene, trichloroethene, and 1,1,1-trichloroethane (45). The maximum contaminant level for VC in drinking water is 2 g/liter, which is lower than for any other volatile organic compound (34). This is consistent with the fact that VC is a known human carcinogen. Reductive dechlorination of VC to ethene (11, 16) and anaerobic oxidation of VC under ironreducing and methanogenic conditions (4, 6) often occur at relatively low rates. The potential for persistence of VC has long been a concern with the exclusive reliance on anaerobic dechlorination as a method for groundwater remediation.In contrast, it is generally accepted that VC is readily biodegradable under aerobic conditions. Cometabolism of VC has been demonstrated with numerous primary substrates, including ethene (17, 28), ethane (17), methane (8, 12), propane (30, 32), propylene (14), isoprene (15), 3-chloropropanol (8), and ammonia (37, 44). Under such conditions, cometabolism of VC occurs faster and with less apparent toxicity than cometabolism of more chlori...

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“…The highest degree of homology was to P. aeruginosa strain AL98, which is a potent degrader of cis-1,4-polyisoprene (29).…”

Section: Resultsmentioning

confidence: 99%

Characterization of an Isolate That Uses Vinyl Chloride as a Growth Substrate under Aerobic Conditions

Verce

Ulrich

Freedman

2000

Appl Environ Microbiol

108

127

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“…Three strains have confirmed rubberdegrading properties: strain VH2 (DSM 44266) from the soil of a Hevea brasiliensis plantation in Vietnam, strain Kd2 (DSM 44302) from foul water inside a deteriorated car tyre in Germany (26) and strain Y2K from a mixed culture formerly considered to be an axenic culture of a rubber-decomposing Pseudomonas aeruginosa strain (2) isolated from foul water inside a deteriorated car tyre in Germany (29). The forth strain was isolated from a clinical specimen (blood sample taken from a aptient'sHickman catheter) (20).…”

Section: Discussionmentioning

confidence: 99%

Gordonia polyisoprenivorans from groundwater contaminated with landfill leachate in a subtropical area: characterization of the isolate and exopolysaccharide production

Fusconi¹,

Godinho²,

Hernandez³

et al. 2006

Braz. J. Microbiol.

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A strain of Gordonia sp. (strain Lc), from landfill leachate-contaminated groundwater was characterized by polyphasic taxonomy and studied for exopolysaccharide (EPS) production. The cells were Gram-positive, catalase-positive, oxidase-negative and non-motile. The organism grew both aerobically and, in anoxic environment, in the presence of NaNO3. Rods occured singly, in pairs or in a typical coryneform V-shaped. The organism had morphological, physiological and chemical properties consistent with its assignment to the genus Gordonia and mycolic and fatty acid pattern that corresponded to those of G. polyisoprenivorans DSM 44302 T . The comparison of the sequence of the first 500 bases of the 16S rDNA of strain Lc gave 100% similarity with the type strain of Gordonia polyisoprenivorans DSM 44302 T . Experiments conducted in anaerobic conditions in liquid E medium with either glucose or sucrose as the main carbon source showed that sucrose did not support the growth of Lc strain and that on glucose the maximum specific growth rate was 0.17h -1 , representing a generation time of approximately 4 hours. On glucose, a maximum of total EPS was produced during the exponential phase (126.17 ± 15.63 g l -1 ). The production of free EPS exceeded that of capsular and the free/capsular EPS ratio increased from 1.9 during the exponential phase to 7.8 during the stationary phase. At present, six strains of G. polyisoprenivorans have been isolated from various environments. Lc is the sixth strain of G. polyisoprenivorans described, the second strain detected in the landfill leachatecontaminated groundwater and the first that is being studied for EPS production.

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“…All cultures were inoculated with cells obtained from a 3-to 6-day-old preculture in Luria-Bertani complex medium (18), and the cells were washed twice with sterile saline before inoculation. Cultivations of the squalane-degrading bacteria on latex agar and synthetic cis-1,4-polyisoprene (IR) was performed as described recently (12,13).…”

Section: Methodsmentioning

confidence: 99%

Microbial Degradation of the Multiply Branched Alkane 2,6,10,15,19,23-Hexamethyltetracosane (Squalane) by Mycobacterium fortuitum and Mycobacterium ratisbonense

Berekaa

Steinbüchel

2000

Appl Environ Microbiol

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Among several bacterial species belonging to the general Gordonia, Mycobacterium, Micromonospora, Pseudomonas, and Rhodococcus, only two mycobacterial isolates, Mycobacterium fortuitum strain NF4 and the new isolate Mycobacterium ratisbonense strain SD4, which was isolated from a sewage treatment plant, were capable of utilizing the multiply branched hydrocarbon squalane (2,6,10,15,19,23-hexamethyltetracosane) and its analogous unsaturated hydrocarbon squalene as the sole carbon source for growth. Detailed degradation studies and high-pressure liquid chromatography analysis showed a clear decrease of the concentrations of squalane and squalene during biomass increase. These results were supported by resting-cell experiments using strain SD4 and squalane or squalene as the substrate. The degradation of acyclic isoprenoids and alkanes as well as of acids derived from these compounds was also investigated. Inhibition of squalane and squalene degradation by acrylic acid indicated the possible involvement of ␤-oxidation in the degradation route. To our knowledge, this is the first report demonstrating the biodegradation of squalane by using defined axenic cultures.

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A Gram-negative bacterium, identified as Pseudomonas aeruginosa AL98, is a potent degrader of natural rubber and synthetic cis-1,4-polyisoprene

Cited by 21 publications

References 11 publications

Characterization of an Isolate That Uses Vinyl Chloride as a Growth Substrate under Aerobic Conditions

Characterization of an Isolate That Uses Vinyl Chloride as a Growth Substrate under Aerobic Conditions

Gordonia polyisoprenivorans from groundwater contaminated with landfill leachate in a subtropical area: characterization of the isolate and exopolysaccharide production

Microbial Degradation of the Multiply Branched Alkane 2,6,10,15,19,23-Hexamethyltetracosane (Squalane) by Mycobacterium fortuitum and Mycobacterium ratisbonense

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