Petroleum hydrocarbon pollution has become one of the global environmental problems, posing a serious threat to the environment and human health. Microbial remediation plays an important role in the remediation of petroleum hydrocarbon-contaminated environment. Nevertheless, the stress factors present in the environment polluted by petroleum hydrocarbons limit the effectiveness of microbial remediation. This paper reviews the common stress factors in petroleum hydrocarbon-polluted environment and the response mechanisms of microorganisms to these factors. Furthermore, we introduce the methods to improve microbial tolerance, such as irrational modification, rational modification based on systems biology tools or tolerance mechanisms, and the construction of microbial consortia. The application of these methods is expected to improve the viability and remediation efficiency of microorganisms in petroleum hydrocarbon-contaminated environment and provide new perspectives and technical support for environmental remediation.
Biodegradation, Environmental ; Petroleum/metabolism* ; Hydrocarbons/isolation & purification* ; Bacteria/genetics* ; Environmental Pollutants/isolation & purification* ; Petroleum Pollution

Mercury (Hg)-contaminated soil poses a significant threat to the environment and human health. Hg-resistant microorganisms have the ability to survive under the stress of inorganic and organic Hg and effectively reduce Hg levels and toxicity. Compared to physical and chemical remediation methods, microbial remediation technologies have garnered increasing attention in recent years due to their lower cost, remarkable efficacy, and minimal environmental impact. This paper systematically elucidates the molecular mechanisms of Hg resistance in microbes, with a focus on their potential applications in phytoremediation of Hg-contaminated soils through plant-microbe interactions. Furthermore, it highlights the critical role of microbes in enhancing the effectiveness of transgenic plants for Hg remediation, aiming to provide a theoretical foundation and scientific basis for the bioremediation of Hg-contaminated soils.
Mercury/toxicity* ; Biodegradation, Environmental ; Soil Pollutants/isolation & purification* ; Soil Microbiology ; Plants, Genetically Modified/metabolism* ; Bacteria/genetics*

Chlorobenzene contaminants (CBs) pose a threat to the eco-environment, and functional strains hold considerable potential for the remediation of CB-contaminated sites. To deeply explore the application potential of functional bacteria in the in-situ bioremediation of CBs, this study focused on the biodegradation characteristics and degradation kinetics of CB and 1, 2-dichlorobenzene (1, 2-DCB) in soil by the isolated strain Serratia marcescens TF-1. Additionally, an in-situ remediation trial was conducted with this strain at a chemical industrial site. Batch serum bottle experiments showed that the degradation rate of CB at the concentrations ranging from 20 to 200 mg/L by TF-1 was 0.22-0.66 mol/(g_cell·h), following the Haldane model, with the optimal concentration at 23.12 mg/L. The results from simulated soil degradation experiments indicated that the combined use of TF-1 and sodium succinate (SS) significantly enhanced the degradation of CBs, with the maximum degradation rate of CB reaching 0.104 d^-1 and a half-life of 6.66 d. For 1, 2-DCB, the maximum degradation rate constant was 0.068 7 d^-1, with a half-life of 10.087 d. The in-situ remediation results at the chemically contaminated site demonstrated that the introduction of bacterial inoculant and SS significantly improved the removal of CBs, achieving the removal rates of 84.2%-100% after 10 d. CB, 1, 4-dichlorobenzene (1, 4-DCB), and benzo[a]pyrene were completely removed. Microbial diversity analysis revealed that the in-situ remediation facilitated the colonization of TF-1 and the enrichment of indigenous nitrogen-fixing Azoarcus, which may have played a key role in the degradation process. This study provides a theoretical basis and practical experience for the in situ bioremediation of CBs-contaminated sites.
Chlorobenzenes/isolation & purification* ; Biodegradation, Environmental ; Soil Pollutants/isolation & purification* ; Serratia marcescens/metabolism* ; Industrial Waste ; Soil Microbiology

Objective: High PM concentration is the main feature of increasing haze in developing states, but information on its microbial composition remains very limited. This study aimed to determine the composition of microbiota in PM in Guangzhou, a city located in the tropics in China. Methods: In Guangzhou, from March 5 to 10 , 2016, PM was collected in middle volume air samplers for 23 h daily. The 16S rDNA V4 region of the PM sample extracted DNA was investigated using high-throughput sequence. Results: Among the Guangzhou samples, , , , , and were the dominant microbiota accounting for more than 90% of the total microbiota, and was the dominant gram-negative bacteria, accounting for 21.30%-23.57%. We examined the difference in bacterial distribution of PM between Beijing and Guangzhou at the genus level; was found in both studies, but was only detected in Guangzhou. Conclusion In conclusion, the diversity and specificity of microbial components in Guangzhou PM were studied, which may provide a basis for future pathogenicity research in the tropics.
Air Microbiology ; Air Pollutants ; analysis ; Bacteria ; classification ; isolation & purification ; China ; Cities ; Environmental Monitoring ; Microbiota ; Particle Size ; Particulate Matter ; analysis ; RNA, Bacterial ; analysis ; RNA, Ribosomal, 16S ; analysis

Global warming caused by the increasing CO2 concentration in atmosphere is a serious problem in the international political, economic, scientific and environmental fields in recent years. Intensive carbon dioxide capture and storage (CCS) technologies have been developed for a feasible system to remove CO2 from industrial exhaust gases especially for combustion flue gas. In these technologies, the biofixation of CO2 by microalgae has the potential to diminish CO2 and produce the biomass. In this review, the current status focusing on biofixation of CO2 from combustion flue gases by microalgae including the selection of microalgal species and effect of flue gas conditions, the development of high efficient photobioreactor and the application of microalgae and its biomass product were reviewed and summarized. Finally, the perspectives of the technology were also discussed.
Air Pollutants ; isolation & purification ; metabolism ; Air Pollution ; prevention & control ; Biodegradation, Environmental ; Carbon Dioxide ; isolation & purification ; metabolism ; Microalgae ; metabolism ; Photochemistry

OBJECTIVEThis paper aims to investigate the impact of anthracene addition on microbial community in agricultural soil irrigated with tap water or reclaimed wastewater.

METHODSThe changes of microbial community were characterized by terminal restriction fragment length polymorphism in combination with 16S rRNA gene clone library analysis.

RESULTSA significant change in microbial community composition was observed during the biodegradation of anthracene, with dominantly enriched members from the genus Methylophilus.

CONCLUSIONThis work might be useful for developing techniques for the isolation of novel putative PAH degrader.

Anthracenes ; analysis ; Bacteria ; classification ; genetics ; isolation & purification ; Biodegradation, Environmental ; DNA, Bacterial ; genetics ; isolation & purification ; Hazardous Waste ; Phylogeny ; Polymorphism, Restriction Fragment Length ; RNA, Ribosomal, 16S ; genetics ; Soil Microbiology ; Soil Pollutants ; analysis ; Waste Disposal, Fluid ; methods

The flocculating yeast strain SPSC01 is a fusant strain of Saccharomyces cerevisiae and Schizosaccharomyces pombe. The use of SPSC01 to absorb Cr(VI) from Cr(VI) containing aqueous solution would greatly reduce the cost of post-adsorption separation, since the superior flocculating property of SPSC01 would allow easy separation of the Cr(VI)-biomass from the solution. In order to investigate the effects of flocculating proteins on Cr(VI) reduction and absorption by SPSC01, the absorption behaviors of SPSC01 and its parental strains were compared. The results showed that Cr(VI) removal rate of SPSC01 was almost the same as that of S. pombe, which also has flocculating ability, but was faster than that of S. cerevisiae, which has no flocculating ability. When the system reached equilibrium, the amount of total Cr adsorbed by S. pombe, SPSC01 and S. cerevisiae were 68.8%, 48.6% and 37.5%, respectively. This showed that flocculation was beneficial to Cr(VI) reduction and adsorption, and suggested that focculating proteins may play a role in enhancing the Cr(VI) adsorption capacity of SPSC01 and S. pombe. We investigated the mechanism of Cr(VI) adsorption by SPSC01 using chemical modification and FTIR. The results indicated that the major functional groups (amino, carboxyl and amide) of surface proteins may contribute to the absorption of Cr(VI).
Adsorption ; Biodegradation, Environmental ; Chromium ; isolation & purification ; Flocculation ; Saccharomyces cerevisiae ; metabolism ; Schizosaccharomyces ; metabolism ; Surface Properties ; Water Pollutants, Chemical ; isolation & purification

White-rot fungus manganese peroxidase (MnP) that has great potential in degrading azo dyes is one of the extracellular glycolsylated heme proteins. MnP from Schizophyllum sp. F17 was isolated and purified by Sephadex G-75 gel filtration chromatography followed by DEAE-cellulose anion exchange chromatography. The molecular weight of the puried enzyme was 49.2 kDa, while the half-life of the MnP in the presence of 0.1 mmol/L H2O2 was 5-6 min. The efficiency of MnP-catalyzed reactions were determined by three key factors: the concentrations of Mn2+, H2O2, and the amount of MnP. Using single factor analysis, an optimized concentration of Mn2+, H2O2 and enzyme were optimized to be 1.2 mmol/L, 0.1 mmol/L, and 0.4 mL, respectively. A response surface methodology (RSM) employing two-level-three-factor full factorial central composite design was used to optimize the catalytic conditions. The result showed that the concentration of H2O2 and the interaction between H2O2 and MnP mostly affect the MnP catalytic efficiency. Finally, we show that the azo dyes could be efficiently decolorized by the purified MnP under optimized conditions.
Azo Compounds ; chemistry ; isolation & purification ; metabolism ; Catalysis ; Coloring Agents ; chemistry ; isolation & purification ; metabolism ; Environmental Pollutants ; chemistry ; isolation & purification ; metabolism ; Fungal Proteins ; chemistry ; isolation & purification ; metabolism ; Peroxidases ; chemistry ; isolation & purification ; metabolism ; Schizophyllum ; enzymology

To study if Solanum nigrum hairy roots can be used for phytoremediation of Cd contamination, we investigated the effects of cadmium (Cd) alone, and in combination with different concentrations of CaCl2, on growth, activities of superoxide dismutase (SOD) and peroxidase (POD) and Cd absorption by hairy roots of S. nigrum L. var pauciflorum. The results showed that Cd concentrations of lower than 50 micromol/L enhanced the growth of hairy roots, while higher than 100 micromol/L inhibited growth and decreased the number of branched roots, also causing the root tips to become brown and shorter in length. In comparison with a control, the soluble protein content, the activities of SOD and POD in hairy roots cultures showed a trend of first increased and then gradually decreased, while the malondialdehyde (MDA) content significantly increased, when increasing the Cd concentrations. Cd concentration of 100 micromol/L or 300 micromol/L in combination with 10-30 mmol/L CaCl2 resulted in a decreased content of soluble protein and MDA in the hairy roots, but an enhanced SOD activity. The increased POD activities were observed when cultured in 100 micromol/L Cd and 10-30 mmol/L CaCl2 but decreased when cultured in 300 micromol/L Cd and 10-30 mmol/L CaCl2. Atomic Absorption Spectrometry determination showed that the Cd absorbed and adsorbed by the hairy roots increased along with the increase of Cd concentration. The exogenous addition of 10-30 mmol/L CaCl2 could reduce the toxicity of Cd. This was achieved on one hand by reducing the absorption of Cd, on the other hand by decreasing the lipid peroxidation through regulating the activities of antioxidant enzymes SOD and POD in the hairy roots.
Absorption ; Biodegradation, Environmental ; Cadmium ; isolation & purification ; metabolism ; Calcium Chloride ; metabolism ; Peroxidase ; metabolism ; Plant Roots ; growth & development ; physiology ; Soil Pollutants ; isolation & purification ; metabolism ; Solanum nigrum ; enzymology ; growth & development ; physiology ; Superoxide Dismutase ; metabolism

Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants that exist extensively in the environment. Microbial degradation is the main pathway of PAHs eradication in natural environment and therefore is of importance to investigate. Advancement has been made in recent years regarding the PAHs molecular degradation mechanisms in bacteria. In this review, we summarized some of the research progresses in microbial PAHs biodegradation pathways (including salicylate pathway and protocatechuate pathway), key enzymes (nah-like, phn, phd, nid and nag) and genes involved. Emphasis was given on naphthalene and phenanthrene which were often used as the representatives of PAHs. It is likely that the new information will promote further research and applications of microbial PAHs biodegradation technology.
Bacteria ; genetics ; metabolism ; Biodegradation, Environmental ; Environmental Pollutants ; isolation & purification ; metabolism ; Naphthalenes ; isolation & purification ; metabolism ; Phenanthrenes ; isolation & purification ; metabolism