Benzyl Alcohol Dehydrogenase (BADH) is an important enzyme for hydrocarbon degradation, which can oxidize benzyl alcohols to aldehydes, while being capable of catalyzing a reversible reaction by reducing benzaldehyde. BADH is a member of medium chain alcohol dehydrogenases, in which zinc and NAD are essential for enzyme activity. This paper describes the expression, purification, and characterization of recombinant benzyl alcohol dehydrogenase, encoded by xylB gene from Rhodococcus ruber UKMP-5M. The gene has been amplified and cloned into E. coli, and the recombinant plasmid pGEMT-xylB has been digested by NdeI and HindIII to construct plasmid pET28b-xylC and then ligated into E. coli BL21 (DE3), itself induced by 0.3 mM isopropyl β-D-thiogalactoside (IPTG) at 25°C. The expressed BADH has been 38 kDa, and is purified by affinity chromatography, in which the specific activity was 30 U/mg after 17 folds purification, leading to a NAD-dependent enzyme that uses benzyl alcohol as a substrate for enzyme characterization. The final metabolite is benzaldehyde, identified by gas chromatography mass spectrometry (GC-MS). The BADH activity has been 0.7 U/mL and the optimum pH and temperature, 9.5 and 30ºC, respectively. Also the Michaelis constant (Km) and maximum velocity (Vmax) have accounted to 705 µM and 1.3 U/mL, respectively. Benzyl alcohol dehydrogenase from R. ruber UKMP-5M can be used for hydrocarbon biodegradation in contaminated sites.

Crude oil contaminant is one of the major problem to environment and its removal process considered as most challenging tool currently across the world. In this degradation study, crude oil hydrocarbons are degraded on various pH optimization conditions (pH 2, 4,6,7,8 and 10) by using two biosurfactant producing bacterial strains Pseudomonas aeruginosa PP3 and Pseudomonas aeruginosa PP4. During crude oil biodegradation, degradative enzymes alkane hydroxylase and alcohol dehydrogenase were examined and found to be higher in PP4 than PP3. Biodegradation efficiency (BE) of crude oil by both PP3 and PP4 were analysed by gas chromatography mass spectroscopy (GCMS). Based on strain PP3, the highest BE was observed in pH 2 and pH 4 were found to be 62% and 69% than pH 6, 7, 8 and 10 (47%, 47%, 49% and 45%). It reveals that PP3 was survived effectively in acidic condition and utilized the crude oil hydrocarbons. In contrast, the highest BE of PP4 was observed in pH 7 (78%) than pH4 (68%) and pH's 2, 6, 8 and 10 (52%, 52%, 43% and 53%) respectively. FTIR spectra results revealed that the presence of different functional group of hydrocarbons (OH, –CH₃, CO, C–H) in crude oil. GCMS results confirmed that both strains PP3 and PP4 were survived in acidic condition and utilized the crude oil hydrocarbons as sole carbon sources. This is the first observation on biodegradation of crude oil by the novel strains of Pseudomonas aeruginosa in acidic condition with higher BE. Overall, the extracellular enzymes and surface active compounds (biosurfactant) produced by bacterial strains were played a key role in crude oil biodegradation process.

Polycyclic aromatic hydrocarbons (PAHs) such as pyrene are universal contaminants existing in the environment which have known cancer-causing and mutagenic characteristics. A psychrophilic bacterial strain Shewanella sp. ISTPL2 was isolated from the sediment sample collected from the Pangong lake, Jammu & Kashmir, India. In our previous study, the pyrene degradation potential of the ISTPL2 strain was studied in both mineral salt media as well as in soil artificially spiked with different concentrations of pyrene. Whole-genome sequencing of ISTPL2 strain in the current study highlighted the key genes of pyrene metabolism, including alcohol dehydrogenase and ring hydroxylating dioxygenase alpha-subunit. Pyrene cytotoxicity was evaluated on HepG2, a human hepato-carcinoma cell line. The cytotoxicity of the organic extract decreased with the increasing duration of bacterial treatment. To develop a more sustainable biodegradation approach, the potential impacts were evaluated for human health and ecosystem using life-cycle assessment (LCA) following the ReCiPe methodology for the considered PAH. The results implemented that global warming potential (GWP) had the highest impact, whereas both ecotoxicity and human toxicity had least from this study.

In the present study, produced water sample collected from the Indian crude oil reservoir is used to enrich the bacterial communities. The impact of these enriched bacterial communities on the biodegradation of crude oil, biofilm formation, and biocorrosion process are elucidated. A crude oil degradation study is carried out with the minimal salt medium and 94% of crude oil was utilized by enriched bacterial communities. During the crude oil degradation many enzymes including alkane hydroxylase, alcohol dehydrogenase, and lipase are playing a key role in the biodegradation processes. The role of enriched bacterial biofilm on biocorrosion reactions are monitored by weight loss studies and electrochemical analysis. Weight loss study revealed that the biotic system has vigorous corrosion attacks compared to the abiotic system. Both AC-Impedance and Tafel analysis confirmed that the nature of the corrosion reaction take place in the biotic system. Very less charge transfer resistance and higher corrosion current are observed in the biotic system than in the abiotic system. Scanning electron microscope confirms that the dense biofilm formation favoured the pitting type of corrosion. X-ray diffraction analysis confirms that the metal oxides formed in the corrosion systems (biotic). From the metagenomic analysis of the V3–V4 region revealed that presence of diverse bacterial communities in the biofilm, and most of them are uncultured/unknown. Among the known genus, Bacillus, Halomonas, etc are dominant in the enriched bacterial biofilm sample. From this study, we conclude that the uncultured bacterial strains are found to be playing a key role in the pitting type of corrosion and they can utilize crude oil hydrocarbons, which make them succeeded in extreme oil reservoir environments.

Hydrocarbons and their derivative compounds are recalcitrant in nature and causing adverse impacts to the environment and are classified as important pollutants. Removal of these pollutants from the atmosphere is a challenging process. Hydrophobic organic pollutants (HOPs) including crude oil, diesel, dotriacontane (C₃₂), and tetracontane (C₄₀) are subjected to the biodegradation study by using a bacterial consortium consist of Bacillus subtilis, Pseudomonas stutzeri, and Acinetobacter baumannii. The impact of pH and temperature on the biodegradation process was monitored. During the HOPs biodegradation, the impact of hydrocarbon-degrading extracellular enzymes such as alcohol dehydrogenase, alkane hydroxylase, and lipase was examined, and found average activity about 47.2, 44.3, and 51.8 μmol/mg⁻¹, respectively. Additionally, other enzymes such as catechol 1,2 dioxygenase and catechol 2,3 dioxygenase were found as 118 and 112 μmol/mg⁻¹ Enzyme as an average range in all the HOPs degradation, respectively. Also, the impact of the extracellular polymeric substance and proteins were elucidated during the biodegradation of HOPs with the average range of 116.90, 54.98 mg/L⁻¹ respectively. The impact of biosurfactants on the degradation of different types of HOPs is elucidated. Very slight changes in the pH were also noticed during the biodegradation study. Biodegradation efficiency was calculated as 90, 84, 76, and 72% for crude oil, diesel, C₃₂, and C₄₀, respectively. Changes in the major functional groups (CH, C–O–C, CO, =CH₂, CH₂, CH₃) were confirmed by FTIR analysis and intermediated metabolites were identified by GCMS analysis. The surface-active molecules along with the enzymes played a crucial role in the biodegradation process.

Fluorotelomer alcohols (FTOHs) are important precursors of perfluorocarboxylic acids (PFCAs) in the environment and biota. With the growing application of 6:2 FTOH [F(CF₂)₆CH₂CH₂OH] in product formulation, it is becoming increasingly urgent to investigate its biological fates in different species. In this study, biotransformation of 6:2 FTOH by young soybean plants (Glycine max L. Merrill) were investigated using hydroponic experiments. During the 144 h-exposure, 6:2 FTCA [F(CF₂)₆CH₂COOH], 6:2 FTUCA [F(CF₂)₅CFCHCOOH], 5:3 FTUCA [F(CF₂)₅CHCHCOOH], 5:3 FTCA [F(CF₂)₅CH₂CH₂COOH], PFHxA [F(CF₂)₅COOH] and PFPeA [F(CF₂)₄COOH] were phase I metabolites in soybean. At the end of exposure, 5:3 FTCA (5.08 mol%), PFHxA (2.34 mol%) and PFPeA (0.58 mol%) were three main metabolites in soybean-solution system. 5:3 FTCA was predominant in soybean roots and stems, while PFHxA was the most abundant product in leaves. PFBA [F(CF₂)₃COOH] and 4:3 FTCA [F(CF₂)₄CH₂CH₂COOH] detected in the hydroponic solution most-likely came from the transformation of 5:3 FTCA by root-associated microbes. Moreover, phase II metabolites of 6:2 FTOH were identified and monitored in soybean tissues. Alcohol dehydrogenase, aldehyde dehydrogenase and glutathione S-transferase were found to participate in 6:2 FTOH metabolism. Based on the phase I and phase II metabolism of 6:2 FTOH in soybean, this study for the first time provides evidences for the transformation pathways of 6:2 FTOH in plants.

The ferrous iron (Fe²⁺) facilitates the formation of root Fe plaque of wetland plants, but its effect on the tolerance of wetland plants to artificial sewage stress has been seldom reported. In this study, the influences of Fe²⁺ on the formation of Fe plaque and its effects on the tolerance of Spartina alterniflora to artificial sewage stress were investigated. The artificial sewage stress decreased the plant height and chlorophyll content and significantly increased the MDA content in leaves. The symptoms of these stresses were alleviated with increasing Fe²⁺ concentration accompanied by significant increase in leaf alcohol dehydrogenase activity. The increase of Fe²⁺ concentration significantly increased the root Fe plaque content and reduced the accumulation of toxic metals in leaves of S. alterniflora. These results support our hypothesis that the exogenous Fe²⁺ supply may enhance the stress resistance of S. alterniflora to artificial sewage containing heavy metals.

The toxicity of levofloxacin to yellow lupin plants was evaluated in this study. Recommended indexes of plant (roots and shoots) growth were determined and new indexes were proposed which better characterise the phytotoxicity of levofloxacin. These were, in particular, the activity of antioxidative enzymes, the content of free radicals, as well as the root protein content and the root protein profile. The results showed that levofloxacin considerably affected EC₅₀, measured as the activity of catalase in roots, and leaves (1.05 and 0.069 mM, respectively). The activity of peroxidase in the roots and the dry weight of seedlings were the least sensitive parameters (EC₅₀ was 1.8 and 1.76 mM, respectively). Units of toxicity clearly showed that the activity of catalase is a better measure of toxicity for low concentrations of the drug, and it is a better index of plant physiological state than the morphological parameters of seedlings. Moreover, levofloxacin changed the location of free radicals and the protein profile in plants. The changes in location of reactive oxygen species in roots were an important symptom of the drug toxicity to lupin seedlings. Our results have shown that the toxicity of levofloxacin was manifested mainly by changes in the protein profile. The content of the glyceraldehyde-3-phosphate dehydrogenase, 14-3-3-like protein A, expansin-B3-like precursor, fructose-bisphosphate aldolase, lipoxygenase, nucleotide-binding subunit of vacuolar ATPase and pyruvate dehydrogenase were found to decrease. On the other hand, plant exposure to levofloxacin resulted in an increase in the content of enolase, protein LlR18A, class III chitinase, ascorbate peroxidase, aspartate aminotransferase, alcohol dehydrogenase 1, leghemoglobin reductase-like 17 and heat shock cognate protein 80-like.

The use of fuels with strong percentage of ethanol that is done in countries such as Brazil and Australia causes a more and more relevant presence of traces of ethanol in natural waters. The ethanol present in these fuels seems to contribute to increase, through various mechanisms, the concentration of hydrocarbons in the same waters and soil. The ethanol content in natural waters must therefore be monitored frequently. It was therefore proposed a very simple innovative method, based on a catalytic fuel cell with the alcohol dehydrogenase enzyme immobilized in the anodic compartment of the device. The analytical performances of this new device were then evaluated by checking traces of alcohol in different types of natural waters (rain, river, and groundwater), with a good degree of precision and with an acceptable level of accuracy.