Packing Incubation and Addition of Rot Fungi Extracts Improve BTEX Elimination from Air in Biotrickling Filters.

The removal of benzene, toluene, ethylbenzene, and xylene (BTEX) from air was investigated in two similar biotrickling filters (BTFs) packed with polyurethane (PU) foam, differing in terms of inoculation procedure (BTF A was packed with pre-incubated PU discs, and BTF B was inoculated via the continuous recirculation of a liquid inoculum). The effects of white rot fungi enzyme extract addition and system responses to variable VOC loading, liquid trickling patterns, and pH were studied. Positive effects of both packing incubation and enzyme addition on biotrickling filtration performance were identified. BFF A exhibited a shorter start-up period (approximately 20 days) and lower pressure drop (75 ± 6 mm H2O) than BTF B (30 days; 86 ± 5 mm H2O), indicating the superior effects of packing incubation over inoculum circulation during the biotrickling filter start-up. The novel approach of using white rot fungi extracts resulted in fast system recovery and enhanced process performance after the BTF acidification episode. Average BTEX elimination capacities of 28.8 ± 0.4 g/(m3 h) and 23.1 ± 0.4 g/(m3 h) were reached for BTF A and BTF B, respectively. This study presents new strategies for controlling and improving the abatement of BTEX in biotrickling filters.

Water potential governs the effector specificity of the transcriptional regulator XylR of Pseudomonas putida.

The biodegradative capacity of bacteria in their natural habitats is affected by water availability. In this work, we have examined the activity and effector specificity of the transcriptional regulator XylR of the TOL plasmid pWW0 of Pseudomonas putida mt-2 for biodegradation of m-xylene when external water potential was manipulated with polyethylene glycol PEG8000. By using non-disruptive luxCDEAB reporter technology, we noticed that the promoter activated by XylR (Pu) restricted its activity and the regulator became more effector-specific towards head TOL substrates when cells were grown under water subsaturation. Such a tight specificity brought about by water limitation was relaxed when intracellular osmotic stress was counteracted by the external addition of the compatible solute glycine betaine. With these facts in hand, XylR variants isolated earlier as effector-specificity responders to the non-substrate 1,2,4-trichlorobenzene under high matric stress were re-examined and found to be unaffected by water potential in vivo. All these phenomena could be ultimately explained as the result of water potential-dependent conformational changes in the A domain of XylR and its effector-binding pocket, as suggested by AlphaFold prediction of protein structures. The consequences of this scenario for the evolution of specificities in regulators and the emergence of catabolic pathways are discussed.

Combined Omics Approach Reveals Key Differences between Aerobic and Microaerobic Xylene-Degrading Enrichment Bacterial Communities: Rhodoferax─A Hitherto Unknown Player Emerges from the Microbial Dark Matter.

Among monoaromatic hydrocarbons, xylenes, especially the ortho and para isomers, are the least biodegradable compounds in oxygen-limited subsurface environments. Although much knowledge has been gained regarding the anaerobic degradation of xylene isomers in the past 2 decades, the diversity of those bacteria which are able to degrade them under microaerobic conditions is still unknown. To overcome this limitation, aerobic and microaerobic xylene-degrading enrichment cultures were established using groundwater taken from a xylene-contaminated site, and the associated bacterial communities were investigated using a polyphasic approach. Our results show that the xylene-degrading bacterial communities were distinctly different between aerobic and microaerobic enrichment conditions. Although members of the genus Pseudomonas were the most dominant in both types of enrichments, the Rhodoferax and Azovibrio lineages were only abundant under microaerobic conditions, while Sphingobium entirely replaced them under aerobic conditions. Analysis of a metagenome-assembled genome of a Rhodoferax-related bacterium revealed aromatic hydrocarbon-degrading ability by identifying two catechol 2,3-dioxygenases in the genome. Moreover, phylogenetic analysis indicated that both enzymes belonged to a newly defined subfamily of type I.2 extradiol dioxygenases (EDOs). Aerobic and microaerobic xylene-degradation experiments were conducted on strains Sphingobium sp. AS12 and Pseudomonas sp. MAP12, isolated from the aerobic and microaerobic enrichments, respectively. The obtained results, together with the whole-genome sequence data of the strains, confirmed the observation that members of the genus Sphingobium are excellent aromatic hydrocarbon degraders but effective only under clear aerobic conditions. Overall, it was concluded that the observed differences between the bacterial communities of aerobic and microaerobic xylene-degrading enrichments were driven primarily by (i) the method of aromatic ring activation (monooxygenation vs dioxygenation), (ii) the type of EDO enzymes, and (iii) the ability of degraders to respire utilizing nitrate.

Evaluation of Bacillus subtilis as a Tool for Biodegrading Diesel Oil and Gasoline in Experimentally Contaminated Water and Soil.

Benzene, toluene, ethylbenzene and xylene (BTEX) are toxic petroleum hydrocarbons pollutants that can affect the central nervous system and even cause cancer. For that reason, studies regarding BTEX degradation are extremely important. Our study aimed evaluate the microorganism Bacillus subtilis as a tool for degrading petroleum hydrocarbons pollutants. Assays were run utilizing water or soil distinctly contaminated with gasoline and diesel oil, with and without B. subtilis. The ability of B. subtilis to degrade hydrophobic compounds was analyzed by Fourier-Transform Infrared Spectroscopy (FTIR) and gas chromatography. The FTIR results indicated, for water assays, that B. subtilis utilized the gasoline and diesel oil to produce the biosurfactant, and, as a consequence, performed a biodegradation process. In the same way, for soil assay, B. subtilis biodegraded the diesel oil. The gas chromatography results indicated, for gasoline in soil assay, the B. subtilis removed BTEX. So, B. subtilis was capable of degrading BTEX, producing biosurfactant and it can also be used for other industrial applications. Bioremediation can be an efficient, economical, and versatile alternative for BTEX contamination.

Influence of growth substrate and contaminant mixtures on the degradation of BTEX and MTBE by Rhodococcus rhodochrous ATCC strain 21198.

The degradation of the prevalent environmental contaminants benzene, toluene, ethylbenzene, and xylenes (BTEX) along with a common co-contaminant methyl tert-butyl ether (MTBE) by Rhodococcus rhodochrous ATCC Strain 21198 was investigated. The ability of 21198 to degrade these contaminants individually and in mixtures was evaluated with resting cells grown on isobutane, 1-butanol, and 2-butanol. Growth of 21198 in the presence of BTEX and MTBE was also studied to determine the growth substrate that best supports simultaneous microbial growth and contaminants degradation. Cells grown on isobutane, 1-butanol, and 2-butanol were all capable of degrading the contaminants, with isobutane grown cells exhibiting the most rapid degradation rates and 1-butanol grown cells exhibiting the slowest. However, in conditions where BTEX and MTBE were present during microbial growth, 1-butanol was determined to be an effective substrate for supporting concurrent growth and contaminant degradation. Contaminant degradation was found to be a combination of metabolic and cometabolic processes. Evidence for growth of 21198 on benzene and toluene is presented along with a possible transformation pathway. MTBE was cometabolically transformed to tertiary butyl alcohol, which was also observed to be transformed by 21198. This work demonstrates the possible utility of primary and secondary alcohols to support biodegradation of monoaromatic hydrocarbons and MTBE. Furthermore, the utility of 21198 for bioremediation applications has been expanded to include BTEX and MTBE.

Pinisolibacter aquiterrae sp. nov., a novel aromatic hydrocarbon-degrading bacterium isolated from benzene-, and xylene-degrading enrichment cultures, and emended description of the genus Pinisolibacter.

Two Gram-reaction-negative strains, designated as B13T and MA2-2, were isolated from two different aromatic hydrocarbon-degrading enrichment cultures and characterized using a polyphasic approach to determine their taxonomic position. The two strains had identical 16S rRNA gene sequences and were most closely related to Pinisolibacter ravus E9T (97.36 %) and Siculibacillus lacustris SA-279T (96.33 %). Cells were facultatively aerobic rods and motile with a single polar flagellum. The strains were able to degrade ethylbenzene as sole source of carbon and energy. The assembled genome of strain B13T had a total length of 4.91 Mb and the DNA G+C content was 68.8 mol%. The predominant fatty acids (>5 % of the total) of strains B13T and MA2-2 were C18 : 1 ω7c/C18 : 1 ω6c, C16 : 1 ω7c/C16 : 1 ω6c and C16 : 0. The major ubiquinone of strain B13T was Q10, while the major polar lipids were phosphatidyl-N-methylethanolamine, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and a phospholipid. Based on phenotypic characteristics and phylogenetic data, it is concluded that strains B13T and MA2-2 are members of the genus Pinisolibacter and represent a novel species for which the name Pinisolibacter aquiterrae sp. nov. is proposed. The type strain of the species is strain B13T (=LMG 32346T=NCAIM B.02665T).

Heilaohuacid G, a new triterpenoid from Kadsura coccinea inhibits proliferation, induces apoptosis, and ameliorates inflammation in RA-FLS and RAW 264.7 cells via suppressing NF-𝜠B pathway.

Heilaohu, the roots of Kadsura coccinea, has been used in Tujia ethnomedicine to treat rheumatic arthritis (RA). Heilaohuacid G (1), a new 3,4-seco-lanostane type triterpenoid isolated from the ethanol extract of Heilaohu, whose structure was determined using HR-ESI-MS data, NMR spectroscopic analyses, and ECD calculations. In this study, our purpose is to elucidate the mechanisms of Heilaohuacid G in the treatment of RA by inhibited proliferation of rheumatoid arthritis-fibroblastoid synovial (RA-FLS) cells and inhibited the inflammatory reactions in LPS-induced RA-FLS and RAW 264.7 cell lines via inhibiting NF-κB pathway. The biological activity screening experiments indicated that Heilaohuacid G significantly inhibited proliferation of RA-FLS cells with IC50 value of 8.16 ± 0.47 µM. CCK-8 assay, ELISA, flow cytometry assay, and Western blot were used to measure the changes of cell viability, apoptosis, and the release of inflammatory cytokines. Heilaohuacid G was found not only induced RA-FLS cell apoptosis, but also inhibited the inflammatory reactions in LPS-induced RA-FLS and RAW 264.7 cell lines via inhibiting NF-κB pathway. Furthermore, Heilaohuacid G (p.o.) at doses of 3.0, 6.0, and 12.0 mg/kg and the ethanol extracts of Heilaohu (p.o.) at doses of 200, 400, and 800 mg/kg both were confirmed antiinflammatory effects on xylene-induced ear mice edema model.

Theoretical investigation of a novel xylene-based light-driven unidirectional molecular motor.

In this study, the working mechanism of the first light-driven rotary molecular motors used to control an eight-base-pair DNA hairpin has been investigated. In particular, this linker was reported to have promising photophysical properties under physiological conditions, which motivated our work at the quantum mechanical level. Cis-trans isomerization is triggered by photon absorption at wavelengths ranging 300 nm-400 nm, promoting the rotor to the first excited state, and it is mediated by an energy-accessible conical intersection from which the ground state is reached back. The interconversion between the resulting unstable isomer and its stable form occurs at physiological conditions in the ground state and is thermally activated. Here, we compare three theoretical frameworks, generally used in the quantum description of medium-size chemical systems: Linear-Response Time-Dependent Density Functional Theory (LR-TDDFT), Spin-Flip TDDFT (SF-TDDFT), and multistate complete active space second-order perturbation theory on state-averaged complete active space self consistent field wavefunctions (MS-CASPT2//SA-CASSCF). In particular, we show the importance of resorting to a multireference approach to study the rotational cycle of light-driven molecular motors due to the occurrence of geometries described by several configurations. We also assess the accuracy and computational cost of the SF-TDDFT method when compared to MS-CASPT2 and LR-TDDFT.

Use of urinary hippuric acid and o-/p-/m-methyl hippuric acid to evaluate surgical smoke exposure in operating room healthcare personnel.

Toluene and xylene are common components of surgical smoke, whereas hippuric acid (HA) and methylhippuric acid (MHA) are the products of toluene and xylene metabolism in humans, respectively. HA and MHA can be used as indicators to evaluate the exposure hazards of toluene and xylene. In this study, we used liquid chromatography tandem mass spectrometry (LC-MS/MS) to simultaneously analyze the HA, o-/m-/p-MHA, and creatinine contents in the urine of healthcare personnel. Concentrations of HA and o-/m-/p-MHAs were normalized to those of creatinine and used to analyze urine samples of 160 operating room (OR) healthcare personnel, including administrative staff, surgical nurses, nurse anesthetists, and surgeons. The results showed that the five analytes could be accurately separated and exhibited good linearity (r > 0.9992). The rate of recovery was between 86% and 106%, and the relative standard deviation was less than 5%. Urine from administrative staff presented the highest median concentration of hippuric acid (0.25 g/g creatinine); this was significantly higher than that found in the urine of surgeons (0.15 g/g). The concentrations of urinary o-/m-/p-MHAs in surgical nurses were higher than those in administrative staff, nurse anesthetists, and surgeons. Furthermore, the type, sex, and age of healthcare personnel were associated with changes in urine HA and o-/m-/p-MHA concentrations. Healthcare personnel should be aware of the risk of exposure to surgical smoke.

Biodegradation of Chloroxylenol by Cunninghamella elegans IM 1785/21GP and Trametes versicolor IM 373: Insight into Ecotoxicity and Metabolic Pathways.

Chloroxylenol (PCMX) is applied as a preservative and disinfectant in personal care products, currently recommended for use to inactivate the SARS-CoV-2 virus. Its intensive application leads to the release of PCMX into the environment, which can have a harmful impact on aquatic and soil biotas. The aim of this study was to assess the mechanism of chloroxylenol biodegradation by the fungal strains Cunninghamella elegans IM 1785/21GP and Trametes versicolor IM 373, and investigate the ecotoxicity of emerging by-products. The residues of PCMX and formed metabolites were analysed using GC-MS. The elimination of PCMX in the cultures of tested microorganisms was above 70%. Five fungal by-products were detected for the first time. Identified intermediates were performed by dechlorination, hydroxylation, and oxidation reactions catalysed by cytochrome P450 enzymes and laccase. A real-time quantitative PCR analysis confirmed an increase in CYP450 genes expression in C. elegans cells. In the case of T. versicolor, spectrophotometric measurement of the oxidation of 2,20-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) showed a significant rise in laccase activity during PCMX elimination. Furthermore, with the use of bioindicators from different ecosystems (Daphtoxkit F and Phytotoxkit), it was revealed that the biodegradation process of PCMX had a detoxifying nature.

Biodegradation of binary mixtures of octane with benzene, toluene, ethylbenzene or xylene (BTEX): insights on the potential of Burkholderia, Pseudomonas and Cupriavidus isolates.

The contamination of the environment by crude oil and its by-products, mainly composed of aliphatic and aromatic hydrocarbons, is a widespread problem. Biodegradation by bacteria is one of the processes responsible for the removal of these pollutants. This study was conducted to determine the abilities of Burkholderia sp. B5, Cupriavidus sp. B1, Pseudomonas sp. T1, and another Cupriavidus sp. X5 to degrade binary mixtures of octane (representing aliphatic hydrocarbons) with benzene, toluene, ethylbenzene, or xylene (BTEX as aromatic hydrocarbons) at a final concentration of 100 ppm under aerobic conditions. These strains were isolated from an enriched bacterial consortium (Yabase or Y consortium) that prefer to degrade aromatic hydrocarbon over aliphatic hydrocarbons. We found that B5 degraded all BTEX compounds more rapidly than octane. In contrast, B1, T1 and X5 utilized more of octane over BTX compounds. B5 also preferred to use benzene over octane with varying concentrations of up to 200 mg/l. B5 possesses alkane hydroxylase (alkB) and catechol 2,3-dioxygenase (C23D) genes, which are responsible for the degradation of alkanes and aromatic hydrocarbons, respectively. This study strongly supports our notion that Burkholderia played a key role in the preferential degradation of aromatic hydrocarbons over aliphatic hydrocarbons in the previously characterized Y consortium. The preferential degradation of more toxic aromatic hydrocarbons over aliphatics is crucial in risk-based bioremediation.

Aerobic degradation of BTEX compounds by Streptomyces species isolated from activated sludge and agricultural soils.

In this study, we tested the ability of Streptomyces to use for their growth benzene, toluene, ethylbenzene, and o-, m-, p-xylenes as sole source of carbon and energy. These bacteria were isolated from agricultural soils and activated sludge samples from a wastewater treatment plant. The results show that Streptomyces are capable of degrading at least one of the BTEX compounds. Among them, 3 isolates from activated sludge called (U, F and V) and a single isolate (SA13) isolated from an agricultural soil, can use as the sole source of carbon and energy, all of these BTEX compounds at concentrations of 1500 mg/L. Based on the analysis of the 16S rRNA gene sequence, two active strains were identified as Streptomyces fimicarius, Streptomyces cavourensis, Streptomyces flavogriseus and Streptomyces pratensis. These strains can be excellent candidates for the bioremediation of the telluric and aquatic sites polluted by these xenobiotics.

Complete Genome Sequence of Kosakonia radicincitans GXGL-4A, a Nitrogen-Fixing Bacterium with Capability to Degrade TEX.

Kosakonia radicincitans GXGL-4A, a free-living nitrogen-fixing (NF) bacterial strain isolated from maize (Zea mays L.) roots was found to have ability to degrade aromatic hydrocarbons. In this study, we describe the main morphological characteristics of bacterium, aromatic hydrocarbon-degrading capability, and the complete genome of K. radicincitans GXGL-4A. The genome is consisted of only one 5,687,681 bp linear chromosome with a G + C content of 53.96%. The strain has two genetically distinct nitrogenase systems, one based on molybdenum (Mo) similar to nitrogenase isolated from a wide range of nitrogen-fixing organisms, and the other contains iron (Fe). The differences in transcriptional level of several important nitrogen fixation (nif) genes between LB (nitrogen-rich, NR) and A15 nitrogen-free (nitrogen-limited, NL) culture conditions were detected using Real-time Quantitative Reverse Transcription PCR (qRT-PCR). The bacterial cells of GXGL-4A can grow well in LB liquid medium containing 1% toluene, ethylbenzene or xylene, suggesting a good resistance to the tested aromatic hydrocarbons. The results of GC-MS analysis showed that K. radicincitans GXGL-4A has a good capability to degrade toluene, ethylbenzene, and xylene (TEX). Completion of the genome sequencing will no doubt contribute to the deep exploration and comprehensive utilization of this NF bacterium in sustainable agriculture and bioremediation of aromatic pollutants.

The pathways by which the marine diatom Thalassiosira sp. OUC2 biodegrades p-xylene, combined with a mechanistic analysis at the proteomic level.

A marine diatom, Thalassiosira sp. OUC2, was isolated from natural seawater collected from Daya Bay, China. This diatom degraded 1.25-40 mg L-1p-xylene within five days, at a removal efficiency exceeding 98%. Gas chromatography-mass spectrometer (GC-MS) analysis indicated that p-xylene was converted into 4-methylbenzyl alcohol, p-toluic acid, and p-cresol in the presence of strain OUC2. Meanwhile, proteomic analysis showed that, after exposure to p-xylene, several algal enzymes were significantly upregulated: including monooxygenase, alcohol dehydrogenase, benzaldehyde dehydrogenase, benzoate 1,2-dioxygenase, and catechol 2,3-dioxygenase. Moreover, ecotoxicological tests suggested that the intermediate metabolites were less toxic than the parent compound (p-xylene). Thalassiosira sp. OUC2 may thus be suitable for the remediation of p-xylene-contaminated marine environments.

Advancing biomarkers for anaerobic o-xylene biodegradation via metagenomic analysis of a methanogenic consortium.

Quantifying functional biomarker genes and their transcripts provides critical lines of evidence for contaminant biodegradation; however, accurate quantification depends on qPCR primers that contain no, or minimal, mismatches with the target gene. Developing accurate assays has been particularly challenging for genes encoding fumarate-adding enzymes (FAE) due to the high level of genetic diversity in this gene family. In this study, metagenomics applied to a field-derived, o-xylene-degrading methanogenic consortium revealed genes encoding FAE that would not be accurately quantifiable by any previously available PCR assays. Sequencing indicated that a gene similar to the napthylmethylsuccinate synthase gene (nmsA) was most abundant, although benzylsuccinate synthase genes (bssA) also were present along with genes encoding alkylsuccinate synthase (assA). Upregulation of the nmsA-like gene was observed during o-xylene degradation. Protein homology modeling indicated that mutations in the active site, relative to a BssA that acts on toluene, increase binding site volume and accessibility, potentially to accommodate the relatively larger o-xylene. The new nmsA-like gene was also detected at substantial concentrations at field sites with a history of xylene contamination.

[Determination of seven urinary metabolites of benzene, toluene and xylene by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry].

Objective: To develop a method using ultra-high performance liquid chromatography-triple quadrupole mass spectrometry to determine the urinary metabolites of benzene, toluene and xylene. The selected metabolites are S-phenylmercapturic acid (S-PMA) , trans, trans-muconic acid (t, t-MA) , 8-hydroxy-2 deoxyguanosine (8-OHdG) , hippuric acid (HA) , 2-methylhippuric acid (2-MHA) , 3-methylhippuric acid (3-MHA) and 4-methylhippuric acid (4-MHA) . Methods: The urine sample was pretreated using methanol to precipitate the proteins. HSS T3 chromatographic column was used to separate the metabolites. The mass spectrometric acquisition was carried out using multiple reaction monitoring (MRM) after ionization with ESI source. External standard method was used for quantification. Results: All the standard curves showed good linear relation, and r of the seven metabolites was all above 0.999. The detection limits and quantitative limits of the seven metabolites were 0.01-500 ng/ml and 0.02-1 000 ng/ml (based on the actual dilution ratio) , respectively. The average spiked recoveries of four loadings ranged from 85.8% to 109.9%. The intra-day and inter-day precisions were 0.2%-4.5% and 0.6%-9.5%, respectively. The samples can be kept for at least 14 days at both 4 ℃ and -20 ℃. Conclusion: This method is simple, rapid and highly sensitive with low cost, and its accuracy, precision and stability can meet the daily test requirements. It can be applied for the determination of urinary S-PMA, t, t-MA, 8-OHdG, HA, 2-MHA, 3-MHA and 4-MHA for the occupational population exposed to benzene, toluene and xylene.

The interplay of EIIANtr with C-source regulation of the Pu promoter of Pseudomonas putida mt-2.

The presence of some sugars (e.g. glucose) downregulates the activity of the Pu promoter of plasmid pWW0 of Pseudomonas putida mt-2, which drives the upper TOL operon for biodegradation of m-xylene. Genetic evidence produced 20 years ago documented an effect of the EIIANtr (PtsN) protein of the nitrogen-related phosphoenolpyruvate-dependent phosphotransferase system (PTSNtr ) in such a C-source control of Pu activity. In this study, we have exploited the wealth of recent information on the PTS of P. putida as well as transcriptomic data available in the last few years on this bacterium to revisit this question - and the role of EIIANtr as such. To this end, we examined Pu output under physiological conditions known to either phosphorylate PTS proteins to saturation or to deplete them altogether from high-energy phosphate. The results showed that Pu activity is checked by EIIANtr regardless of its phosphorylation state. However, such inhibition is intensified during growth on glucose (which correlates with more phosphate-free EIIANtr ) and partially relieved in fructose, which triggers phosphorylation of PTS proteins. These data explain former inconsistencies on the Pu-PTSNtr interplay and provides a better understanding of the metabolic and regulatory retroactivity between the TOL plasmid and its host metabolism.

Sphingobium aquiterrae sp. nov., a toluene, meta- and para-xylene-degrading bacterium isolated from petroleum hydrocarbon-contaminated groundwater.

A Gram-negative, aerobic, slightly yellow-pigmented bacterium, designated as SKLS-A10T, was isolated from groundwater sample of the 'Siklós' petroleum hydrocarbon contaminated site (Hungary). Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain SKLS-A10T formed a distinct phyletic lineage within the genus Sphingobium. It shared the highest 16S rRNA gene homology with Sphingobium abikonense DSM 23268T (97.29 %), followed by Sphingobium lactosutens DSM 23389T (97.23 %), Sphingobium phenoxybenzoativorans KCTC 42448T (97.16 %) and Sphingobium subterraneum NBRC 109814T (96.74 %). The predominant fatty acids (>5 % of the total) are C18 : 1ω7c, C14 : 0 2-OH, C16 : 1ω7c/iso C15 : 0 2-OH, C17 : 1ω6c and C16 : 0. The major ubiquinone is Q-10. The predominant polyamine is spermidine. The major polar lipids are sphingoglycolipid and diphosphatidylglycerol. The DNA G+C content of strain SKLS-A10T is 65.9 mol%. On the basis of evidence from this taxonomic study using a polyphasic approach, strain SKLS-A10T represents a novel species of the genus Sphingobium for which the name Sphingobiumaquiterrae sp. nov. is proposed. The type strain is SKLS-A10T (=DSM 106441T=NCAIM B. 02634T).

Sulfur dioxide and o-xylene co-treatment in biofilter: Performance, bacterial populations and bioaerosols emissions.

Sulfur dioxide (SO2) and benzene homologs are frequently present in the off-gas during the process of sewage sludge drying. A laboratory scale biofilter was set up to co-treat SO2 and o-xylene in the present study. SO2 and o-xylene could be removed simultaneously in a single biofilter. Their concentration ratio in the inlet stream influenced the removal efficiencies. It is worth noting that the removal of SO2 could be enhanced when low concentrations of o-xylene were introduced into the biofilter. Pseudomonas sp., Paenibacillus sp., and Bacillus sp. were the main functional bacteria groups in the biofilter. Sulfur-oxidizing bacteria (SOB) and o-xylene-degrading bacteria (XB) thrived in the biofilter and their counts as well as their growth rate increased with the increase in amount of SO2 and o-xylene supplied. The microbial populations differed in counts and species due to the properties and components of the compounds being treated in the biofilter. The presence of mixed substrates enhanced the diversity of the microbial population. During the treatment process, bioaerosols including potentially pathogenic bacteria, e.g., Acinetobacter lwoffii and Aeromonas sp., were emitted from the biofilter. Further investigation is needed to focus on the potential hazards caused by the bioaerosols emitted from waste gas treatment bioreactors.

Production of Bacillus amyloliquefaciens OG and its metabolites in renewable media: valorisation for biodiesel production and p-xylene decontamination.

Biosurfactants are important in many areas; however, costs impede large-scale production. This work aimed to develop a global sustainable strategy for the production of biosurfactants by a novel strain of Bacillus amyloliquefaciens. Initially, Bacillus sp. strain 0G was renamed B. amyloliquefaciens subsp. plantarum (syn. Bacillus velezensis) after analysis of the gyrA and gyrB DNA sequences. Growth in modified Landy's medium produced 3 main recoverable metabolites: surfactin, fengycin, and acetoin, which promote plant growth. Cultivation was studied in the presence of renewable carbon (as glycerol) and nitrogen (as arginine) sources. While diverse kinetics of acetoin production were observed in different media, similar yields (6-8 g·L-1) were obtained after 72 h of growth. Glycerol increased surfactin-specific production, while arginine increased the yields of surfactin and fengycin and increased biomass significantly. The specific production of fengycin increased ∼10 times, possibly due to a connecting pathway involving arginine and ornithine. Adding value to crude extracts and biomass, both were shown to be useful, respectively, for the removal of p-xylene from contaminated water and for biodiesel production, yielding ∼70 mg·g-1 cells and glycerol, which could be recycled in novel media. This is the first study considering circular bioeconomy to lower the production costs of biosurfactants by valorisation of both microbial cells and their primary and secondary metabolites.