Decai Jin

Biodegradation of di-n-butyl phthalate by an isolated Gordonia sp. strain QH-11: Genetic identification and degradation kinetics

Di-n-butyl phthalate (DBP) is one of the most widely used phthalic acid esters (PAEs), which have shown increasing environmental concerns worldwide. A bacterial strain designated as QH-11, was isolated from activated sludge and found to be capable of utilizing DBP as carbon and energy sources for growth. 16S rRNA and gyrb gene sequence analysis revealed that strain QH-11 was most closely related to Gordonia sp. Kinetics studies of DBP degradation by the strain QH-11 revealed that DBP depletion curves fit with the modified Gompertz model (R(2)>0.98). Meanwhile, substrate utilization tests showed that strain QH-11 could utilize other common PAEs and also the main intermediate product phthalic acid (PA). A gene encoding the large subunit of the phthalate dioxygenase, which is responsible for PA degradation, was successfully detected in strain QH-11. Furthermore, the results of reverse transcription quantitative PCR demonstrate that mRNA expression level of phthalate dioxygenase increased significantly after strain QH-11 was induced by DBP and PA.

Biodegradation of Di-n-Butyl Phthalate by a Newly Isolated Halotolerant Sphingobium sp.

A Gram-negative strain (TJ) capable of growing aerobically on mixed phthalate esters (PAEs) as the sole carbon and energy source was isolated from the Haihe estuary, Tianjin, China. It was identified as belonging to the Sphingobium genus on the basis of morphological and physiological characteristics and 16S rRNA and gyrb gene sequencing. The batch tests for biodegradation of di-n-butyl phthalate (DBP) by the Sphingobium sp. TJ showed that the optimum conditions were 30 °C, pH 7.0, and the absence of NaCl. Stain TJ could tolerate up to 4% NaCl in minimal salt medium supplemented with DBP, although the DBP degradation rates slowed as NaCl concentration increased. In addition, substrate tests showed that strain TJ could utilize shorter side-chained PAEs, such as dimethyl phthalate and diethyl phthalate, but could not metabolize long-chained PAEs, such as di-n-octyl phthalate, diisooctyl phthalate, and di-(2-ethyl-hexyl) phthalate. To our knowledge, this is the first report on the biodegradation characteristics of DBP by a member of the Sphingobium genus.

Analysis of bacterial community in bulking sludge using culture-dependent and -independent approaches.

The bacterial community of a bulking sludge from a municipal wastewater treatment plant with anoxic-anaerobic-oxic process was investigated by combination of cultivation and 16S rRNA gene clone library analysis for understanding the causes of bulking. A total of 28 species were obtained from 63 isolates collected from six culture media. The most cultivable species belonged to gamma-Proteobacteria including Klebsiella sp., Pseudomonas sp., Aeromonas sp. and Acinetobacter sp. Further analysis of these strains by repetitive sequence based on polymerase chain reaction (rep-PCR) technology showed that rep-PCR yielded discriminatory banding patterns within the same genus using REP and BOX primer sets. While the culture-independent assessment revealed that beta-Proteobacteria was the dominant group in the bulking sample. Sequence analysis revealed that the highest proportion (14.7%) of operational taxonomic units was 98% similar to Candidatus Accumulibacter phosphatis, which is used to remove phosphorous from wastewater. Our results indicated that combining different approaches can produce complementary information, thus generate a more accurate view of microbial community in bulking sludge.

Biodegradation of di-n-Butyl Phthalate by Achromobacter sp. Isolated from Rural Domestic Wastewater

A bacterial strain W-1, isolated from rural domestic wastewater, can utilize the environmental hormone di-n-butyl phthalate (DBP) as the sole carbon and energy source. The isolated bacterium species was confirmed to belong to the genus Achromobacter based on its 16S rRNA gene sequence. The results of substrate utilization tests showed that the strain W-1 could utilize other common phthalates and phenol. High-performance liquid chromatography analysis revealed that the optimal conditions for DBP degradation were pH 7.0, 35 °C, and an agitation rate of 175 rpm. Under these conditions, 500 mg/L of DBP was completely degraded within 30 h. The effects of heavy metals (50 mg/L Cu2+ and 500 mg/L Pb2+) and surfactants (100 mg/L SDS and 500 mg/L Tween 20) on DBP degradation were investigated. The results demonstrated that Cu2+ and SDS severely inhibited DBP degradation and Pb2+ weakly inhibited DBP degradation, while Tween 20 greatly enhanced DBP degradation. Furthermore, phthalate degradation genes were found to be located on a plasmid present in Achromobacter sp. W-1.

Terrimonas pekingensis sp. nov., isolated from bulking sludge, and emended descriptions of the genus Terrimonas, Terrimonas ferruginea, Terrimonas lutea and Terrimonas aquatica.

A Gram-negative, strictly aerobic, non-motile and non-spore-forming rod that produced white, viscous colonies, designated QH(T), was isolated from bulking sludge collected from a municipal wastewater treatment plant in Beijing, China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain QH(T) belonged to the genus Terrimonas and shared 96.3 % sequence similarity with Terrimonas lutea DY(T), 94.1 % with Terrimonas ferruginea ATCC 13524(T) and 93.8 % with Terrimonas aquatica RIB1-6(T). Strain QH(T) contained iso-C15 : 0, summed feature 3 (comprising one or more of C16 : 1ω7c, C16 : 1ω6c and iso-C15 : 0 2-OH) and iso-C15 : 1 G as the predominant fatty acids. The predominant polar lipid of strain QH(T) and members of the genus Terrimonas was phosphatidylethanolamine. The major isoprenoid quinone of strain QH(T) was MK-7 and the DNA G+C content was 41.0 mol%. DNA-DNA relatedness between strain QH(T) and T. lutea BCRC 17944(T), T. ferruginea BCRC 17943(T) and T. aquatica BCRC 17941(T) was 32, 23 and 22 %, respectively. On the basis of phylogenetic inference, differential phenotypic data and low DNA-DNA relatedness with members of the genus Terrimonas, strain QH(T) represents a novel species, for which the name Terrimonas pekingensis sp. nov. is proposed. The type strain is QH(T) ( = CICC 10452(T)  = NCCB 100397(T)). The descriptions of the genus Terrimonas and T. ferruginea, T. lutea and T. aquatica are also emended.

Draft Genome Sequence of Brevibacillus panacihumi Strain W25, a Halotolerant Hydrocarbon-Degrading Bacterium.

ABSTRACT Brevibacillus panacihumi strain W25 was isolated from hydrocarbon-contaminated saline soil. Here, we report the 5.5-Mb draft genome sequence of this strain, which may provide insights into the mechanism of microbial hydrocarbon degradation in saline environments.

Draft Genome Sequence of Advenella kashmirensis Strain W13003, a Polycyclic Aromatic Hydrocarbon-Degrading Bacterium

ABSTRACT Advenella kashmirensis strain W13003 is a polycyclic aromatic hydrocarbon (PAH)-degrading bacterium isolated from PAH-contaminated marine sediments. Here, we report the 4.8-Mb draft genome sequence of this strain, which will provide insights into the diversity of A. kashmirensis and the mechanism of PAH degradation in the marine environment.

Draft Genome Sequence of Halotolerant Polycyclic Aromatic Hydrocarbon-Degrading Pseudomonas bauzanensis Strain W13Z2.

ABSTRACT Pseudomonas bauzanensis W13Z2 is a halotolerant polycyclic aromatic hydrocarbon (PAH)-degrading bacterium isolated from petroleum-contaminated drill cuttings in the Bohai Sea. Here, we report the 8.6-Mb draft genome sequence of this strain, which will provide insights into the diversity of Pseudomonas and the mechanism of PAHs degradation in drill cuttings.

Characterization and Genomic Analysis of a Highly Efficient Dibutyl Phthalate-Degrading Bacterium Gordonia sp. Strain QH-12

A bacterial strain QH-12 isolated from activated sludge was identified as Gordonia sp. based on analysis of 16S rRNA gene sequence and was found to be capable of utilizing dibutyl phthalate (DBP) and other common phthalate esters (PAEs) as the sole carbon and energy source. The degradation kinetics of DBP under different concentrations by the strain QH-12 fit well with the modified Gompertz model (R2 > 0.98). However, strain QH-12 could not utilize the major intermediate product phthalate (phthalic acid; PA) as the sole carbon and energy source, and only a little amount of PA was detected. The QH-12 genome analysis revealed the presence of putative hydrolase/esterase genes involved in PAEs-degradation but no phthalic acid catabolic gene cluster was found, suggesting that a novel degradation pathway of PAEs was present in Gordonia sp. QH-12. This information will be valuable for obtaining a more holistic understanding on diverse genetic mechanisms of PAEs-degrading Gordonia sp. strains.

Draft Genome Sequence of Ochrobactrum anthropi Strain W13P3, a Halotolerant Polycyclic Aromatic Hydrocarbon-Degrading Bacterium

ABSTRACT Ochrobactrum anthropi W13P3 was isolated from saline soil contaminated by polycyclic aromatic hydrocarbons (PAHs) and could degrade PAHs with 5% NaCl. We report the 5.3-Mb draft genome sequence of this strain, which is helpful for understanding the diversity of Ochrobactrum spp. and the mechanism of PAH degradation in saline environments.