A Global Proteomic Change in Petroleum Hydrocarbon-Degrading Pseudomonas aeruginosa in Response to High and Low Concentrations of Petroleum Hydrocarbons

A comprehensive review on arsenic contamination in groundwater: Sources, detection, mitigation strategies and cost analysis

While groundwater is commonly perceived as safe, the excessive presence of trace metals, particularly arsenic (As), can pose significant health hazards. This review examines the current scenario of pollutants and their mitigations focusing on As contamination in groundwater across multiple nations, with a specific emphasis on the Indian Peninsula. Arsenic pollution surpasses the WHO limit of 10 ppb in 107 countries, impacting around 230 million people worldwide, with a substantial portion in Asia, including 20 states and four union territories in India. Analysis of the correlation between the aquifer and arsenic poisoning highlights severe contamination in groundwater originating from loose sedimentary aquifer strata, particularly in recently formed mountain ranges with geological sources presumed to contribute over 90% of arsenic pollution, i.e. a big environmental challenge. A myriad of techniques, including chromatographic, electrochemical, biological, spectroscopic, and colorimetric methods among others, are available for the detection and removal of arsenic from groundwater. Removal strategies encompass a wide array of approaches such as bioremediation, adsorption, coagulation/flocculation, ion exchange, biological processes, membrane treatment, and oxidation techniques specifically tailored for affected areas. Constructed wetlands help to eliminate heavy metal impurities such as As, Zn, Cd, Cu, Ni, Fe, and Cr. Their efficiency is influenced by design and environmental factors. Nanotechnology and nanoparticles have recently been studied to remove arsenic and toxic metal ions from water. Cost-effective solutions including community-based mitigation initiatives, alongside policy and regulatory frameworks addressing arsenic contamination, are essential considerations.

Genome and metabolome analysis of Bacillus sp. Hex-HIT36: A newly screened functional microorganism for the degradation of 1-hexadecene in industrial wastewater

1-Hexadecene has been detected at a level of mg/L in both influent and effluent of wastewater treatment plants situated in chemical/pharmaceutical industrial parks, which poses a potential threat to the environment. However, few reports are available on aerobic metabolic pathways and microorganisms involved in 1-Hexadecene degradation. In this study, a new strain of 1-Hexadecene-degrading bacteria, Bacillus sp. Hex-HIT36 (HIT36), was isolated from the activated sludge of a wastewater treatment plants located in an industrial park. The physicochemical properties and degradation efficacy of HIT36 were investigated. HIT36 was cultured on a medium containing 1-Hexadecene as a sole carbon source; it was found to remove ∼67% of total organic carbon as confirmed by mass spectrometric analysis of intermediate metabolites. Metabolomic and genomic analysis showed that HIT36 possesses various enzymes, namely, pyruvate dehydrogenase, dihydropolyhydroxyl dehydrogenase, and 2-oxoglutarate-2-oxoiron oxidoreductase (subunit alpha), which assist in the metabolization of readily available carbon source or long chain hydrocarbons present in the growth medium/vicinity. This suggests that HIT36 has efficient long-chain alkane degradation efficacy, and understanding the alkane degradation mechanism of this strain can help in developing technologies for the degradation of long-chain alkanes present in wastewater, thereby assisting in the bioremediation of environment.

Genome analysis for the identification of genes involved in phenanthrene biodegradation pathway in Stenotrophomonas indicatrix CPHE1. Phenanthrene mineralization in soils assisted by integrated approaches

Phenanthrene (PHE) is a highly toxic compound, widely present in soils. For this reason, it is essential to remove PHE from the environment. Stenotrophomonas indicatrix CPHE1 was isolated from an industrial soil contaminated by polycyclic aromatic hydrocarbons (PAHs) and was sequenced to identify the PHE degrading genes. Dioxygenase, monooxygenase, and dehydrogenase gene products annotated in S. indicatrix CPHE1 genome were clustered into different trees with reference proteins. Moreover, S. indicatrix CPHE1 whole-genome sequences were compared to genes of PAHs-degrading bacteria retrieved from databases and literature. On these basis, reverse transcriptase-polymerase chain reaction (RT-PCR) analysis pointed out that cysteine dioxygenase (cysDO), biphenyl-2,3-diol 1,2-dioxygenase (bphC), and aldolase hydratase (phdG) were expressed only in the presence of PHE. Therefore, different techniques have been designed to improve the PHE mineralization process in five PHE artificially contaminated soils (50 mg kg^-1), including biostimulation, adding a nutrient solution (NS), bioaugmentation, inoculating S. indicatrix CPHE1 which was selected for its PHE-degrading genes, and the use of 2-hydroxypropyl-β-cyclodextrin (HPBCD) as a bioavailability enhancer. High percentages of PHE mineralization were achieved for the studied soils. Depending on the soil, different treatments resulted to be successful; in the case of a clay loam soil, the best strategy was the inoculation of S. indicatrix CPHE1 and NS (59.9% mineralized after 120 days). In sandy soils (CR and R soils) the highest percentage of mineralization was achieved in presence of HPBCD and NS (87.3% and 61.3%, respectively). However, the combination of CPHE1 strain, HPBCD, and NS showed to be the most efficient strategy for sandy and sandy loam soils (LL and ALC soils showed 35% and 74.6%, respectively). The results indicated a high degree of correlation between gene expression and the rates of mineralization.

Current research on simultaneous oxidation of aliphatic and aromatic hydrocarbons by bacteria of genus Pseudomonas

One of the most frequently used methods for elimination of oil pollution is the use of biological preparations based on oil-degrading microorganisms. Such microorganisms often relate to bacteria of the genus Pseudomonas. Pseudomonads are ubiquitous microorganisms that often have the ability to oxidize various pollutants, including oil hydrocarbons. To date, individual biochemical pathways of hydrocarbon degradation and the organization of the corresponding genes have been studied in detail. Almost all studies of this kind have been performed on degraders of individual hydrocarbons belonging to a single particular class. Microorganisms capable of simultaneous degradation of aliphatic and aromatic hydrocarbons are very poorly studied. Most of the works on such objects have been devoted only to phenotype characteristic and some to genetic studies. To identify the patterns of interaction of several metabolic systems depending on the growth conditions, the most promising are such approaches as transcriptomics and proteomics, which make it possible to obtain a comprehensive assessment of changes in the expression of hundreds of genes and proteins at the same time. This review summarizes the existing data on bacteria of the genus Pseudomonas capable of the simultaneous oxidation of hydrocarbons of different classes (alkanes, monoaromatics, and polyaromatics) and presents the most important results obtained in the studies on the biodegradation of hydrocarbons by representatives of this genus using methods of transcriptomic and proteomic analyses.

Temperature-induced changes in the proteome of Pseudomonas aeruginosa during petroleum hydrocarbon degradation

Petroleum hydrocarbon contaminants, which are among the most serious pollutants in the petroleum industry, can be degraded sufficiently by Pseudomonas aeruginosa. However, temperature-induced stress will severely inhibit this biodegradation. In this study, the proteome of P. aeruginosa P6 at 25 °C, 43 °C and 37 °C was used to examine the impact of temperature on the molecular mechanism of biodegradation of petroleum hydrocarbon by P. aeruginosa P6. Differentially expressed proteins were identified by iTRAQ technology, and the functions of these proteins were identified by bioinformatic analysis. The impact of 25 °C and 43 °C on cellular processes has also been discussed. The results showed that the expression of proteins in chemotaxis toward petroleum hydrocarbons, terminal oxidation of aromatic rings in petroleum hydrocarbons and trans-membrane transport of fatty acids and nutriments were clearly inhibited under 25 °C condition. The expression of proteins in chemotaxis, emulsification, adhesion and terminal oxidation of petroleum hydrocarbons; catalysis of fatty alcohols and fatty aldehydes; trans-membrane transport of nutriments and β-oxidation were clearly inhibited under 43 °C condition.

Efficient biodegradation of petroleum n-alkanes and polycyclic aromatic hydrocarbons by polyextremophilic Pseudomonas aeruginosa san ai with multidegradative capacity

Pseudomonas aeruginosa san ai degraded individual selected petroleum compounds: n-hexadecane, n-nonadecane, fluorene, phenanthrene, and pyrene with high efficiency, at initial concentrations of 20 mg L⁻¹ and in seven days.