Bacterial Degradation Research Articles

Pretreatment by a novel photo-electro reactor to control organic and biofouling during reverse osmosis filtration of reclaimed water

This study reports the performance of a novel photo-electro filtration (PEF) reactor consisting of an IrO2/RuO2 coated anodic filter and UV lamp to pretreat biologically treated wastewater effluent prior to reverse osmosis (RO) filtration. Synthetic model solutions and biologically treated wastewater effluent were used for systematic evaluation of the PEF reactor performance in terms of organic degradation, bacterial inactivation, biofilm formation reduction, and ultimately RO fouling mitigation. Experiments with model solutions containing proteins (Bovine Serum Albumin) and bacteria (Pseudomonas aeruginosa) show that UV irradiation and electrochemical treatment with increasing voltage input resulted in superior bacterial inactivation, biofilm formation reduction, and effective organic degradation. When the PEF reactor was used to pretreat biologically treated wastewater effluent, electrochemical treatment at 3 V alone and the combination of electrochemical treatment at 3 V and UV could achieve near complete bacterial inactivation and good fouling reduction during subsequent RO operation. However, the combination of electrochemical treatment at 3 V and UV was superior over electrochemical treatment at 3 V alone in several aspects including fouling reduction and reduced risk of membrane degradation due to chlorine residue. The underlying mechanisms responsible for effective PEF pretreatment performance were elucidated by monitoring the fate of free chlorine, hydroxyl radicals (indirectly monitored by measuring concentration of the quenching chemical N-n-dimethyl-p-nitrosoaniline), H2O2, quorum sensing signal molecules, and organic fractions during UV irradiation and electrochemical treatment. Effective bio and organic fouling mitigation by PEF pretreatment was attributed to the enhanced bacterial inactivation and degradation of organic compounds (primarily protein-like and humic-like substances) by hydroxyl radicals (∙OH) produced from photo-electrochemical treatment.

Bacteria use a catabolic patchwork pathway of apparently recent origin for degradation of the synthetic buffer compound TRIS.

The synthetic buffer compound TRIS (2-amino-2-(hydroxymethyl)propane-1,3-diol) is used in countless applications, and no detailed information on its degradation has been published so far. Herein, we describe the discovery of a complete bacterial degradation pathway for TRIS. By serendipity, a Pseudomonas strain was isolated from sewage sludge that was able to grow with TRIS as only carbon and nitrogen source. Genome and transcriptome analyses revealed two adjacent gene clusters embedded in a mobile genetic element on a conjugative plasmid to be involved in TRIS degradation. Heterologous gene expression revealed cluster I to encode a TRIS uptake protein, a TRIS alcohol dehydrogenase, and a TRIS aldehyde dehydrogenase, catalyzing the oxidation of TRIS into 2-hydroxymethylserine. Gene cluster II encodes a methylserine hydroxymethyltransferase (mSHMT) and a d-serine dehydratase that plausibly catalyze the conversion of 2-hydroxymethylserine into pyruvate. Conjugational plasmid transfer into Pseudomonas putida KT2440 enabled this strain to grow with TRIS and with 2-hydromethylserine, demonstrating that the complete TRIS degradation pathway can be transmitted by horizontal gene transfer. Subsequent enrichments from wastewater purification systems led to the isolation of further TRIS-degrading bacteria from the Pseudomonas and Shinella genera carrying highly similar TRIS degradation gene clusters. Our data indicate that TRIS degradation evolved recently via gene recruitment and enzyme adaptation from multiple independent metabolic pathways, and database searches suggest that the TRIS degradation pathway is now globally distributed. Overall, our study illustrates how engineered environments can enhance the emergence of new microbial metabolic pathways in short evolutionary time scales.

Bacterial degradation of phenol: a review of the current state of knowledge

Phenol is a toxic and recalcitrant contaminant widely used in various industries, including petrochemical, pharmaceutical, and agrochemical industries. Bacterial degradation of phenol is a promising method for treating phenol-contaminated wastewater. The biodegradation of phenol by bacteria can effectively remove it from the environment, making it a valuable alternative to traditional chemical treatment methods. This review summarizes the current knowledge on the bacterial biodegradation of phenol, including those in the petrochemical, pharmaceutical, and agrochemical sectors, the metabolic pathways involved in phenol degradation, and the factors that influence the efficiency of phenol biodegradation. This paper also discusses the challenges and limitations of using bacteria for the biodegradation of phenol, including the need for further research to improve the efficiency and sustainability of the process. The outcome of this review demonstrates that bacterial biodegradation is a promising and effective method for treating phenol-contaminated wastewater and provides a foundation for future research to improve the efficiency and continuous use of this process.

Potential of Bacterial Isolates and Consortiums for Degrading Linear Alkylbenzenesulfonate, Ammonia, and Phosphate in the Kaliotic River

River pollution by various organic and inorganic compounds such as linear alkylbenzenesulfonate (LAS), ammonia, and phosphate is a serious environmental problem in the Kaliotic River. This research investigates the potential of bacterial isolates and consortia for degrading these pollutants. We conducted a field survey and collected water samples from the Kaliotic River and isolated bacteria from these water samples. Next, we tested the ability of single isolates and bacterial consortia to degrade LAS, ammonia, and phosphate in vitro. The results showed that various bacterial isolates isolated from the Kaliotic River showed varying abilities to degrade LAS, ammonia, and phosphate. Some single isolates could degrade LAS to a significant extent, whereas other isolates showed higher activity in reducing ammonia and phosphate concentrations in the medium. The bacterial consortium consisting of several isolates also showed promising potential for degrading these three pollutants. Further analysis using molecular techniques such as 16S rRNA DNA sequencing shows the genetic diversity of bacteria involved in pollutant degradation. This study also highlights the importance of environmental factors such as temperature, pH, and nutrient availability in influencing bacterial degradation activity. These findings indicate that bacterial isolates and consortia have great potential for degrading LAS, ammonia, and phosphate in the Kaliotic River. This research provides new insights into the potential application of microbes in environmental remediation efforts in polluted rivers. By better understanding the mechanisms of degradation and the factors that influence bacterial activity, it is hoped that more effective and sustainable strategies can be developed to rid rivers of these dangerous pollutants.

Protein degradation in bacteria: focus on the ClpP protease

Proteins in the cells are born (synthesized), work, and die (decomposed). In the life of a protein, its birth is obviously important, but how it dies is equally important in living organisms. Proteases secreted into the outside of cells are used to decompose the external proteins and the degradation products are taken as the nutrients. On the other hand, there are also proteases that decompose unnecessary or harmful proteins which are generated in the cells. In eukaryotes, a large enzyme complex called the proteasome is primarily responsible for degradation of such proteins. Bacteria, which are prokaryotes, have a similar system as the proteasome. We would like to explain the bacterial degradation system of proteins or the death of proteins, which is performed by ATP-dependent protease Clp, with a particular focus on the ClpXP complex, and with an aspect as a target for antibiotics against bacteria.

Microbe-pesticide interactions: Soil enzyme analysis and bacterial degradation of chlorpyrifos

With the objective of understanding microbe—pesticide interactions in soil, the effect of pesticides alone and in combination on the activities of amylase, cellulase, and invertase was assessed in black, and red soils collected from the groundnut (Arachis hypogaea L.) cultivated fields of Andhra Pradesh, India. In addition, the potential bacteria that can break down chlorpyrifos was identified using biochemical assays and a partial 16S rRNA gene sequence analysis. Soil enzymes were analyzed using standard procedures described elsewhere. The activities of amylase, cellulase, and invertase were solely dependent on the dose of pesticides used in the current study. Enzyme activities were significantly increased at the level of 2.5 or 5.0 kg ha–1, whereas increases in the concentration of pesticides at 7.5–10 kg ha−1 were lethal to the enzyme activities in both soils at 10-day incubation. The effective combination for the increase in the activities of amylase, cellulase, and invertase were monocrotophos + mancozeb. Mineral salts medium with 50 ppm chlorpyrifos as a carbon source had the greatest growth of the bacteria (i.e. Pseudomonas citronellolis strain CF3) at 14th h of incubation with OD value of 0.24 at 660 nm, and the same strain could eliminate 75% of the chlorpyrifos within 24 h from the medium. Based on the present study it was concluded that insecticides used alone or in combination with fungicides at specific doses (2.5 or 5.0 kg ha−1) improved the amylase, cellulase, and invertase activities, which are involved in the carbon cycle in soils. Pseudomonas citronellolis strain CF3 is a potential bacterium in the remediation of chlorpyrifos-contaminated sites.

Microbial Degradation Of Calcium Oxalate And Its Potential Application

Calcium oxalate is a naturally occurring compound found in various plants and minerals, and its accumulation in the kidney leads to the formation of kidney stones in humans. One of the main causes of kidney stone formation is a decrease in the number of intestinal microbiota which are capable of degrading calcium oxalate. This study focuses on bacterial degradation of calcium oxalate accumulated in humans. Searching for Calcium oxalate degrading strain with high degrading activity has become one of the priorities from the context of research. The study aimed to isolate and characterize microorganisms which are capable of degrading calcium oxalate. Calcium oxalate degrading microorganisms were isolated from faecal samples by using MRS-calcium oxalate medium. Calcium oxalate degrading bacteria were identified on the basis of colour reduction on calcium oxalate medium plate after the incubation period. The morphological and biochemical characterization of isolates were studied. Quantitative determination of degradation was performed by using an indole assay. The activity of isolates was observed by the degradation of kidney stones. Isolates showed better results for degradation of kidney stones after 2 weeks of the incubation period.

Effects of alpine meadows with different degradation gradients on the stability of the soil micro-foodweb in the Tibetan Plateau

Resource-transfer connections among bacteria, fungi, and microbivorous nematodes play an integral role in the decomposition pathways of soil micro-foodweb. Exploring the response of soil bacteria, fungi, and nematodes to grassland degradation is crucial for predicting the direction and trajectory of degradation. However, the knowledge about soil bacteria-fungi-nematode interactions in ecosystem function and nutrient cycling must be highlighted properly, especially in the Qinghai-Tibet Plateau. Therefore, this study focuses on four alpine meadows at different degenerate gradients (non-degraded grassland, slightly degraded grassland, moderately degraded grassland, and severely degraded grassland) on the Qinghai-Tibet Plateau. The investigation of soil bacteria-fungi-nematode interactions uses high-throughput sequencing and correlation network analysis. The results demonstrate significant variations in the composition of soil nematode genera, and bacterial and fungal phyla, across different degradation stages. Moreover, the diversity of nematodes, bacteria and fungi declined as grassland degradation worsened. Principal component analysis (PCA) revealed that alpine meadows with varying degradation gradients significantly influenced the community structure of bacteria, fungi, and nematodes. Mantel analysis indicated that soil water content (P < 0.05), total phosphorus (P < 0.05), and total nitrogen (P < 0.05) were the primary soil properties affecting the soil bacterial community. Similarly, available soil potassium (P < 0.05), microbial biomass carbon (P < 0.05), and microbial biomass nitrogen (P < 0.05) were the main soil factors influencing the soil fungal community. In contrast, the correlation between individual soil characteristics and soil nematodes did not reach a significant level, suggesting that a blend of physical and chemical properties regulates the soil nematode community. As grassland degradation intensified, the number of links in the interaction network of bacteria, fungi, and nematodes increased. Particularly, the networks between fungi and nematodes expanded, and the key species within each network varied with the different stages of grassland degradation. Concurrently, soil micro-foodweb decomposition pathways shifted. In the ND treatment, bacteria and fungi jointly dominated the degradation channels of the soil micro-food web, while the LD and MD treatments mainly dominated the degradation channels of fungi. On the other hand, SD treatment was dominated by bacterial degradation channels. This research adds to our theoretical understanding of meadow soil micro-foodwebs and the sustainable use of alpine grasslands in the Qinghai-Tibet Plateau.

Overexpression of endogenous multi-copper oxidases mcoA and mcoC in Rhodococcus jostii RHA1 enhances lignin bioconversion to 2,4-pyridine-dicarboxylic acid.

To improve the titre of lignin-derived pyridine-dicarboxylic acid (PDCA) products in engineered Rhodococcus jostii RHA1 strains, plasmid-based overexpression of seven endogenous and exogenous lignin-degrading genes was tested. Overexpression of endogenous multi-copper oxidases mcoA, mcoB, and mcoC was found to enhance 2,4-PDCA production by 2.5-, 1.4-, and 3.5-fold, respectively, while overexpression of dye-decolorizing peroxidase dypB was found to enhance titre by 1.4-fold, and overexpression of Streptomyces viridosporus laccase enhanced titre by 1.3-fold. The genomic context of the R. jostii mcoA gene suggests involvement in 4-hydroxybenzoate utilization, which was consistent with enhanced whole cell biotransformation of 4-hydroxybenzoate by R. jostii pTipQC2-mcoA. These data support the role of multi-copper oxidases in bacterial lignin degradation, and provide an opportunity to enhance titres of lignin-derived bioproducts.

Multiple spatial scales of bacterial and fungal structural and functional traits affect carbon mineralization.

Studying the functional heterogeneity of soil microorganisms at different spatial scales and linking it to soil carbon mineralization is crucial for predicting the response of soil carbon stability to environmental changes and human disturbance. Here, a total of 429 soil samples were collected from typical paddy fields in China, and the bacterial and fungal communities as well as functional genes related to carbon mineralization in the soil were analysed using MiSeq sequencing and GeoChip gene microarray technology. We postulate that CO2 emissions resulting from bacterial and fungal carbon mineralization are contingent upon their respective carbon consumption strategies, which rely on the regulation of interactions between biodiversity and functional genes. Our results showed that the spatial turnover of the fungal community was 2-4 times that of the bacterial community from hundreds of meters to thousands of kilometres. The effect of spatial scale exerted a greater impact on the composition rather than the functional characteristics of the microbial community. Furthermore, based on the establishment of functional networks at different spatial scales, we observed that both bacteria and fungi within the top 10 taxa associated with carbon mineralization exhibited a prevalence of generalist species at the regional scale. This study emphasizes the significance of spatial scaling patterns in soil bacterial and fungal carbon degradation functions, deepening our understanding of how the relationship between microbial decomposers and soil heterogeneity impacts carbon mineralization and subsequent greenhouse gas emissions.

Bacterial Consortium-Mediated Hydrocarbon Degradation of Waste Engine Oils

The automotive and industrial activities are considered one of the important sources of pollution with the increasing amount of WEO released to the environment. One of the ways to solve this problem is through bioremediation. It is, however, challenging since used engine oil contains complex hydrocarbon compounds and is toxic towards the environment and living organisms. Biodegradation by single species bacterium is limited to a small range of hydrocarbon compounds. Hence, a better strategy is to use a synergistic action of different microbial members in a consortium. Different waste engine oils from the motorcycle workshop (MW), urban vehicle workshop (UVW), and heavy vehicle workshop (HVW) were tested for degradation by a bacterial consortium culture. A two-level factorial design experiment was carried out to evaluate the effect of different WEO and nitrogen concentrations towards the growth of the bacterial culture and hydrocarbon degradation in shake flask fermentation. The bacterial consortium culture grown in mineral salts medium (MSM) supplemented with MW (Viscosity, 82 mPa.s) was shown to exhibit the highest biomass with 0.37 (OD600) with 8% (v/v) WEO and 5 g/L nitrogen from ammonium chloride (NH4Cl). Pareto chart of biomass with WEO and nitrogen concentration showed a positive effect for MW and UVW, while a negative effect for HVW which was presumed due to the toxicity, higher complexity of hydrocarbon composition and higher viscosity of WEO from heavy vehicles. Subsequently, GC-MS analysis indicated the degradation of various polyaromatic hydrocarbon (PAH) and BTEX compounds such as naphthalene, benzene, and toluene in the three WEO samples. Assessment of cell hydrophobicity of the culture grown on all three WEO exhibited high cell hydrophobicity, with HVW showing the highest cell hydrophobicity of 81%. This suggests that the bacterial culture altered cell hydrophobicity to facilitate hydrocarbon uptake.

Modelling terrigenous DOC across the north west European Shelf: Fate of riverine input and impact on air-sea CO2 fluxes

Terrigenous carbon in aquatic systems is increasingly recognised as an important part of the global carbon cycle. Despite this, the fate and distribution of terrigenous dissolved organic carbon (tDOC) in coastal and oceanic systems is poorly understood. We have implemented a theoretical framework for the degradation of tDOC across the land to ocean continuum in a 3D hydrodynamical-biogeochemical model on the North West European Shelf. A key feature of this model is that both photochemical and bacterial tDOC degradation rates are age dependant constituting an advance in our ability to describe carbon cycling in the marine environment. Over the time period 1986-2015, 182±17 Gmol yr−1 of riverine tDOC is input to the shelf. Results indicate that bacterial degradation is by far the most important process in removing tDOC on the shelf, contributing to 73±6 % (132±11 Gmol yr−1) of the total removal flux, while 21±3 % (39±6 Gmol yr−1) of riverine tDOC was advected away from the shelf and photochemical degradation removing 5±0.5 % of the riverine flux. Explicitly including tDOC in the model decreased the air-sea carbon dioxide (CO2) flux by 112±8 Gmol yr−1 (4±0.4 %), an amount approximately equivalent to the CO2 released by the UK chemical industry in 2020. The reduction is equivalent to 62 % of the riverine tDOC input to the shelf while approximately 17 % of riverine input is incorporated into the foodweb. This work can improve the assumptions of the fate of tDOC by Earth System Models and demonstrates that the inclusion of tDOC in models can impact ecosystem dynamics and change predicted global carbon budgets for the ocean.

Changes in Fe-redox and Fe-species across the end-Permian ‘Dead Zone’ in the Sydney Basin, Australia (252.10 ± 0.06 Ma): Evidence from X-ray absorption spectroscopy

The end-Permian mass extinction event is traceable across several non-marine basins in Australia. In the Sydney Basin, the lithological succession is characterized by a change from coal seams to mudstones and sandstones, recording a major environmental change following the disappearance of the Permian vegetation. A few millimeter-thick iron-rich ‘rusty’ layer occurs between the uppermost Permian coal seam and the mudstone, a layer that extends laterally across the basin and which has also been documented from coeval successions in Antarctica. This layer is overlain by the <1.5-m-thick Frazer Beach Member, whose basal 10-cm-thick microbreccia bed comprises 99% kaolinite and quartz, and is dated as 252.10 ± 0.06 Ma. The Frazer Beach Member corresponds to the so-called end-Permian ‘Dead Zone’ lacking fossil pollen and leaves. This distinctive member was deposited directly following the extinction of the Permian peat-forming forests.Here we identify, through X-ray absorption spectroscopy, a drastic redox shift across the extinction interval with increasing amount of reduced Fe-species followed by highly oxidized Fe-species, most resembling Fe(III) complexed with organic matter. Values subsequently normalise in younger samples through the ‘Dead Zone’, attaining only slightly higher redox-levels than before the event. The organically complexed Fe-species in the event bed is consistent with the standard Suwannee River fulvic acid, an acid Fe-complex with iron bound to organic matter, whereas the samples above and below the extinction layer yield spectra predominantly resembling magnetite (Fe3O4) mineral phase. We consider that the iron redox fluctuation marking the extinction interval is related to significant environmental changes with accumulation of organic matter following the mass extinction. The highly reduced iron in the extinction layer may relate to methane release from bacterial degradation, or emissions from clathrates. The presence of fulvic acid in the distinct iron-rich extinction layer indicates that an abrupt onset of the process of degradation of plant matter, lipids and calcium hydroxide (CaOH) took place, resulting in this ‘Death layer’. This was followed by millions of years of erosive conditions before new, complex vegetation could establish.

Effect of Rhodococcus bioaugmentation and biostimulation on dibenzothiophene biodegradation and bacterial community interaction in petroleum-contaminated soils

Bioremediation can be effective method for achieving polycyclic aromatic hydrocarbons (PAHs) degradation in soil contaminated with petroleum. The aim of this study was to compare the effect of Rhodococcus bioaugmentation (BIOE) and biostimulation (BIOS) on dibenzothiophene biodegradation and bacterial community interaction in petroleum-contaminated soils. The findings revealed that compared to natural degradation treatment (NAT) and BIOS, BIOE had the highest dibenzothiophene (DBT) and the majority of DBT degradation occurred within the first 30 days. BIOS had a positive impact in the early stage but an opposite effect in the later stages for degrading DBT. Beta diversity analysis revealed significant differences of bacterial composition among NAT, BIOS, and BIOE. Sequencing results indicated that Bacillus and Paenibacillus were dominant genera involved in DBT degradation. Network analysis revealed co-occurrence patterns and connectivity, with BIOE exhibiting higher connectivity and the highest number of links in BIOS. In summary, Rhodococcus bioaugmentation was the simplest and effective method to enhance the clustering degree of bacterial network and DBT degradation in petroleum-contaminated soil, compared to NAT and BIOS.

Distribution of copper-binding ligands in Fram Strait and influences from the Greenland Shelf (GEOTRACES GN05)

The Fram Strait represents the major gateway of Arctic Ocean waters towards the Nordic Seas and North Atlantic Ocean and is a key region to study the impact of climate change on biogeochemical cycles. In the region, information about trace metal speciation, such as copper, is scarce. This manuscript presents the concentrations and conditional stability constants of copper-binding ligands (LCu and log KcondCu2+L) in the water column of Fram Strait and the Greenland shelf (GEOTRACES cruise GN05). Cu-binding ligands were analysed by Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) using salicylaldoxime (SA) as competitive ligand. Based on water masses and the hydrodynamic influences, three provinces were considered (coast, shelf, and Fram Strait) and differences were observed between regions and water masses. The strongest variability was observed in surface waters, with increasing LCu concentrations (mean values: Fram Strait = 2.6 ± 1.0 nM; shelf = 5.2 ± 1.3 nM; coast = 6.4 ± 0.8 nM) and decreasing log KcondCu2+L values (mean values: Fram Strait = 15.7 ± 0.3; shelf = 15.2 ± 0.3; coast = 14.8 ± 0.3) towards the west. The surface LCu concentrations obtained above the Greenland shelf indicate a supply from the coastal environment to the Polar Surface Water (PSW) which is an addition to the ligand exported from the central Arctic to Fram Strait. The significant differences (in terms of LCu and log KcondCu2+L) between shelf and coastal samples were explained considering the processes which modify ligand concentrations and binding strengths, such as biological activity in sea-ice, phytoplankton bloom in surface waters, bacterial degradation, and meltwater discharge from 79NG glacier terminus. Overall, the ligand concentration exceeded those of dissolved Cu (dCu) and kept the free copper (Cu2+) concentrations at femtomolar levels (0.13–21.13 fM). This indicates that Cu2+ toxicity limits were not reached and dCu levels were stabilized in surface waters by organic complexes, which favoured its transport to the Nordic Seas and North Atlantic Ocean and the development of microorganism.

Structural characterization of PaaX, the main repressor of the phenylacetate degradation pathway in Escherichia coli W: A novel fold of transcription regulator proteins

PaaX is a transcriptional repressor of the phenylacetic acid (PAA) catabolic pathway, a central route for bacterial aerobic degradation of aromatic compounds. Induction of the route is achieved through the release of PaaX from its promoter sequences by the first compound of the pathway, phenylacetyl-coenzyme A (PA-CoA). We report the crystal structure of PaaX from Escherichia coli W. PaaX displays a novel type of fold for transcription regulators, showing a dimeric conformation where the monomers present a three-domain structure: an N-terminal winged helix-turn-helix domain, a dimerization domain similar to the Cas2 protein and a C-terminal domain without structural homologs. The domains are separated by a crevice amenable to harbour a PA-CoA molecule. The biophysical characterization of the protein in solution confirmed several hints predicted from the structure, i.e. its dimeric conformation, a modest importance of cysteines and a high dependence of solubility and thermostability on ionic strength. At a moderately acidic pH, the protein formed a stable folding intermediate with remaining α-helical structure, a disrupted tertiary structure and exposed hydrophobic patches. Our results provide valuable information to understand the stability and mechanism of PaaX and pave the way for further analysis of other regulators with similar structural configurations.

Biodegradation of naphthalene – Ecofriendly approach for soil pollution mitigation

Naphthalene (NPT), a widely used household pest repellent and insecticide obtained from crude oil, serves as a toxic pollutant to non-target living matter. The stable and resistant nature of NPT makes it difficult to degrade through the physiochemical processes. The present study investigated the bacterial degradation of NPT isolated from crude oil-contaminated soil. Initially, the potent bacteria, Bacillus sp. GN 3.4, were isolated by enrichment culture method and subsequently assessed for NPT biodegradation. The optimum conditions for NPT biodegradation were pH 7.0 at 37 °C, 80 mg/L (initial NPT), 3% v/v (inoculum dose), and 7 days of treatment which showed 100% biodegradation. Furthermore, GC–MS analysis revealed the presence of degradation metabolites, namely, salicylate and hydroquinone indicating potential metabolic pathways. Considering the water-solubility and non-toxic nature of these metabolites, the results imply that Bacillus sp. GN 3.4. could potentially play a role in bioremediation by aiding in eliminating NPT from the soil.

Functional conservation and preservation of waterlogged archaeological wood

Waterlogged archaeological wood of shipwrecks has been preserved under seawater for centuries, such that microbial erosion has caused severe bacterial degradation and acidification. These wooden cultural relics are of great significance for understanding the shipbuilding technology, trade activities, and environmental ecology of centuries ago. From the perspective of structure and composition, these waterlogged archeological woods have the characteristics of high water content and a large loss of lignin and cellulose, which makes the hull prone to collapse during preservation. Therefore, it is urgent to apply conservation and preservation treatments for deacidification and consolidation. Due to the fragility of wood and the complexity of repair work, the current development of conservation and preservation technology has multiple aims, such as antibacterial, deacidification, and reinforcement effects. In this editorial, the current challenges and conservation treatments with antimicrobial or deacidification utilities will be introduced.

Dietary Chinese herbal mixture supplementation improves production performance by regulating reproductive hormones, antioxidant capacity, immunity, and intestinal health of broiler breeders

Chinese herbs have been used as feed additives and are commonly utilized in domestic intensive livestock farming. However, their impact on the production performance and intestinal health of broiler breeders has yet to be thoroughly explored. This study aimed to evaluate the effects of a Chinese herbal mixture (CHM) on the production performance of broiler breeders in terms of reproductive hormones, antioxidant capacity, immunity, and intestinal health of broiler breeders. A total of 336 thirty-wk-old hens were randomly allotted to 4 groups with 6 replicates of fourteen hens each, which fed a basal diet supplemented with 0 (CON), 500 (CHM500), 1,000 (CHM1000), and 1,500 (CHM1500) mg/kg CHM for 56 days, respectively. Our results showed that dietary supplementation with CHM1000 increased the laying rate and number of SYF and decreased the feed conversion ratio (P < 0.05). All CHM groups increased oviduct and ovarian indexes, serum E2 and T-AOC levels, and decreased serum TG and MDA levels compared with CON (P < 0.05). In comparison to the CON group, the CHM1000 and CHM1500 groups increased serum ALB, IgM, and IL-10 levels, whereas the CHM1000 group also increased serum TP and SOD levels, and the CHM1500 group increased serum P and decreased serum TNF-α (P < 0.05). The addition of CHM increased FSHR expressions in the ovary, Claudin-1 expressions in the jejunum, and SOD1 expressions in the liver and ovary, but decreased the mRNA expressions of INH in the ovary as well as IL-2 and IL-6 expressions in the jejunum (P < 0.05). Moreover, CHM500 and CHM1000 groups increased CAT, GPx, and HO-1 expression in the ovary, and SOD1 and GPx expression in the jejunum, while decreasing IL-17A expression in the jejunum (P < 0.05). In addition, CHM1000 and CHM1500 groups increased villus height, VCR, and the mRNA expressions of Nrf2, HO-1, Occludin, and MUC2 in the jejunum, and IL-10 expression in the ovary, while decreasing IL-2 and IL-17A expression in the ovary, in addition to increasing GPx, Nrf2, HO-1, NQO1, and IL-10 expression in the liver (P < 0.05). Supplementation with CHM1000 increased ESR-α, ESR-β, GnRH, Nrf2, and NQO1 expression in the ovary, but decreased IFN-γ expression in the ovary as well as crypt depth in the jejunum (P < 0.05). Supplementing CHM1500 increased NQO1 and ZO-1 expression in the jejunum and decreased IL-2 in the liver (P < 0.05). The high-throughput sequencing results showed that dietary CHM1000 supplementation altered the composition of the intestinal microbiota, as evidenced by the regulation of the genera Lactobacillus, Faecalibacterium, and Phascolarctobacterium. PICRUSt analysis revealed that metabolic pathways of bacterial chemotaxis, butanoate metabolism, and synthesis and degradation of ketone bodies were enriched in the CHM1000 group. Spearman's correlation analysis indicated that the differentiated genera were significantly associated with the production performance, serum hormone, and gut barrier-related genes. Taken together, supplementation of CHM, especially at 1,000 mg/kg, could improve production performance by regulating reproductive hormones, antioxidant capacity, immunity, and intestinal health of broiler breeders, and maybe provide insights into its application as a potential feed additive to promote the performance of broiler breeders.

Isolation and characterization of a newly chrysene-degrading Achromobacter aegrifaciens.

Polycyclic aromatic hydrocarbons (PAHs) are considered substances of potential human health hazards because of their resistance to biodegradation and carcinogenic index. Chrysene is a PAH with a high molecular weight (HMW) that poses challenges for its elimination from the environment. However, bacterial degradation is an effective, environmentally friendly, and cost-effective solution. In our study, we isolated a potential chrysene-degrading bacteria from crude oil-contaminated seawater (Bizerte, Tunisia). Based on 16SrRNA analysis, the isolate S5 was identified as Achromobacter aegrifaciens. Furthermore, the results revealed that A. aegrifaciens S5 produced a biofilm on polystyrene at 20 °C and 30 °C, as well as at the air-liquid (A-L) interface. Moreover, this isolate was able to swim and produce biosurfactants with an emulsification activity (E24%) over 53%. Chrysene biodegradation by isolate S5 was clearly assessed by an increase in the total viable count. Confirmation was obtained via gas chromatography-mass spectrometry (GC-MS) analyses. A. aegrifaciens S5 could use chrysene as its sole carbon and energy source, exhibiting an 86% degradation of chrysene on day 7. In addition, the bacterial counts reached their highest level, over 25 × 1020 CFU/mL, under the conditions of pH 7.0, a temperature of 30 °C, and a rotary speed of 120 rpm. Based on our findings, A. aegrifaciens S5 can be a potential candidate for bioremediation in HMW-PAH-contaminated environments.