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To reveal the characteristics of indigenous microbiome including the pathogenic-related ones on Angkor monuments in Cambodia and the distribution pattern of resistome at different locations, several sites, namely Angkor Wat, Bayon of Angkor Thom, and Prasat Preah Vihear with different exposure levels to tourists were selected to conduct the metagenomic analysis in this study. The general characteristics of the microbiome on these monuments were revealed, and the association between the environmental geo-ecological feature and the indigenous microbiome was delineated. The most common microbial groups included 6 phyla, namely Acidobacteria, Actinobacteria, Gemmatimonadetes, Nitrospirae, Proteobacteria and Verrucomicrobia on the monuments, but Firmicutes and Chlamydiae were the most dominant phyla found in bats droppings. The taxonomic family of Chitinophagaceae could serve as a signature microbial group for Preah Vihear, the less visited site. More importantly, the pathogenic-related characteristics of the microbiome residing on Angkor monuments were uncovered. A set of specific antibiotic resistance genes (ARGs) with cross-niches dispersal capacity (between the environmental microbiome and the microbiome within warm blood fauna) was identified to be high by the source tracking analysis based on ARGs profile varies in this study. Among the 10 ARG-types detected in this study, 6 of them are confined to resistance mechanism of antibiotic efflux-pump. The findings of this study provide new a new direction on public health management and implication globally at archaeological sites for tourism.

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Introduction: The expanded granular sludge bed (EGSB) is a major form of anaerobic digestion system during wastewater treatment. Yet, the dynamics of microbial and viral communities and members functioning in nitrogen cycling along with monthly changing physicochemical properties have not been well elucidated. Methods: Here, by collecting the anaerobic activated sludge samples from a continuously operating industrial-scale EGSB reactor, we conducted 16S rRNA gene amplicon sequencing and metagenome sequencing to reveal the microbial community structure and variation with the ever-changing physicochemical properties along within a year. Results: We observed a clear monthly variation of microbial community structures, while COD, the ratio of volatile suspended solids (VSS) to total suspended solids (TSS) (VSS/TSS ratio), and temperature were predominant factors in shaping community dissimilarities examined by generalized boosted regression modeling (GBM) analysis. Meanwhile, a significant correlation was found between the changing physicochemical properties and microbial communities (p <0.05). The alpha diversity (Chao1 and Shannon) was significantly higher (p <0.05) in both winter (December, January, and February) and autumn (September, October, and November) with higher organic loading rate (OLR), higher VSS/TSS ratio, and lower temperature, resulting higher biogas production and nutrition removal efficiency. Further, 18 key genes covering nitrate reduction, denitrification, nitrification, and nitrogen fixation pathways were discovered, the total abundance of which was significantly associated with the changing environmental factors (p <0.05). Among these pathways, the dissimilatory nitrate reduction to ammonia (DNRA) and denitrification had the higher abundance contributed by the top highly abundant genes narGH, nrfABCDH, and hcp. The COD, OLR, and temperature were primary factors in affecting DNRA and denitrification by GBM evaluation. Moreover, by metagenome binning, we found the DNRA populations mainly belonged to Proteobacteria, Planctomycetota, and Nitrospirae, while the denitrifying bacteria with complete denitrification performance were all Proteobacteria. Besides, we detected 3,360 non-redundant viral sequences with great novelty, in which Siphoviridae, Podoviridae, and Myoviridae were dominant viral families. Interestingly, viral communities likewise depicted clear monthly variation and had significant associations with the recovered populations (p <0.05). Discussion: Our work highlights the monthly variation of microbial and viral communities during the continuous operation of EGSB affected by the predominant changing COD, OLR, and temperature, while DNRA and denitrification pathways dominated in this anaerobic system. The results also provide a theoretical basis for the optimization of the engineered system.

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Studies on marine bacterial communities have revealed endemism in local communities, yet the underlying mechanisms remained elusive. Environmental gradient settings can benefit the straightaway study of community composition changes and the mechanisms explaining them. Here, MiSeq-based 16S rRNA gene sequencing was performed on 12 surface sediment samples from the northern South China Sea (nSCS) revealing that shallow-sea samples had a higher alpha diversity than deep-sea samples, and were differentiated from them significantly based on beta diversity. Temperature, seawater depth, and salinity were the top three influential factors. Bacterial 16S rRNA gene abundance was positively correlated with temperature, and negatively correlated with salinity. Sulfate-reducing bacteria including Desulfobacteraceae, Desulfobulbaceae, and Syntrophobacteraceae were enriched in shallow-sea sediments, co-abundant with nitrite-oxidizing Nitrospira and potential sulfur-oxidizing shallow-sea specific Woeseiaceae/JTB255 clade. Meanwhile, the co-existing and co-abundant of marine anammox and n-damo bacteria were enriched in deep-sea sediments, which was firstly evidenced in this study. The global deep-sea cosmopolitans, OM1 clade, and deep-sea specific Woeseiaceae/JTB255 clade were also found enriched in deep-sea sediments of nSCS. The discovery of novel taxa which were differentially enriched in shallow-/deep-sea sediments not only shed light on enigmatic physiological properties and the natural selection mechanism, but also provided the potential ecological-functional links which invoked further genomics-based metabolic characteristics.

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Analytical method which combines electronic tongue technique and chemometrics analysis is developed to discriminate oil types and predict oil quality. All the studied Camellia oil samples from pressing, n-hexane extraction and supercritical CO2 extraction (SCCE), were successfully identified by principal component analysis (PCA) and hierarchical cluster analysis (HCA). Furthermore, multi factor linear regression model (MLRM) was established to predict oil quality, which are indicated by acid value (AV) and peroxide value (POV). The practical potential of e-tongue for the discrimination and assessment of Camellia oils has shown promising application in the characterization of Camellia oils in the oil quality evaluation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-021-00973-1.

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Pretreatment plays a key role in biofuel production from lignocellulosic biomass. In this study, the main factors of peroxyformic acid (PA) pretreatment were optimized in the light of enzymolysis efficiency and composition analysis of pretreated sugarcane bagasse (SCB). Lignin was significantly removed (59.0%) and a complete saccharification level (103.6%) was obtained for the pretreated SCB with slight cellulose loss (9.2%) under the optimized pretreatment conditions. The effects of PA pretreatment on the structural characteristics of SCB were also studied and the digestibility of pretreated SCB was also evaluated by dark fermentative hydrogen production with an enriched anaerobic cellulolytic microbial consortium MC1. The hydrogen production increased by 195.5% (based on initial SCB) and the abundance of dominant hemicellulose-degradation genus Thermoanaerobacterium increased from 23.8% to 40.2% due to the remaining and accessible hemicellulose in PA pretreated SCB.

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Two pyrene-degrading strains, Pseudomonas aeruginosa PA06 and Achromobacter sp. AC15 were co-incubated in equal proportions as a microbiological consortium and could enhance the degradation of pyrene. The enzymatic activities of the catechol 1,2-dioxygenase (C12O) and 2,3-dioxygenase activities (C23O) were produced complementary expression by P. aeruginosa PA06 and Achromobacter sp. AC15, respectively. Meanwhile, results showed that pyrene degradation was sufficiently promoted in the presence of sodium citrate as a co-metabolic carbon source, likely a result of enhanced biomass and biosurfactant production. The optimized dosage and ideal initial pHs were 1.4 g L-1 and 5.5, respectively. We also analyzed the rate constant of pyrene degradation, cell growth, and enzyme activity. Results show that P. aeruginosa PA06 had a better effect than Achromobacter sp. AC15 in bacterial growth. However, the C23O or C12O activity produced by Achromobacter sp. AC15 continued at a similar or even faster than that of P. aeruginosa PA06. The mixed bacteria had a better effect than any single bacteria, suggesting the strains worked synergistically to enhance the degradation efficiency. In the co-metabolism system of 600 mg/L pyrene and 1.4 g/L sodium citrate, pyrene degradation reached 74.6%, was 1.57 times, 2.06 times, and 3.89 times that of the mix-culture strains, single PA06 and single AC15 without sodium citrate, respectively. Overall, these findings are valuable as a potential tool for the bioremediation of high-molecular-weight PAHs.

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Microbial remediation has become one of the most important strategies for eliminating petroleum pollutants. Revealing the transcript maps of microorganisms with the hydrocarbon-degrading ability contributes to enhance the degradation of hydrocarbons and further improve the effectiveness of bioremediation. In this study, we characterized the transcriptome of hydrocarbon-degrading Achromobacter sp. HZ01 after petroleum treatment for 16h. A total of 38,706,280 and 38,954,413 clean reads were obtained by RNA-seq for the petroleum-treated group and control, respectively. By an effective de novo assembly, 3597 unigenes were obtained, including 3485 annotated transcripts. Petroleum treatment had significantly influenced the transcriptional profile of strain HZ01, involving 742 differentially expressed genes. A part of genes were activated to exert specific physiological functions, whereas more genes were down-regulated including specific genes related to cell motility, genes associated with glycometabolism, and genes coding for ribosomal proteins. Identification of genes related to petroleum degradation revealed that the fatty acid metabolic pathway and a part of monooxygenases and dehydrogenases were activated, whereas the TCA cycle was inactive. Additionally, terminal oxidation might be a major aerobic pathway for the degradation of n-alkanes in strain HZ01. The newly obtained data contribute to better understand the gene expression profiles of hydrocarbon-degrading microorganisms after petroleum treatment, to further investigate the genetic characteristics of strain HZ01 and other related species and to develop cost-effective and eco-friendly strategies for remediation of crude oil-polluted environments.

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Extracts of 19 selected edible flowers were investigated for their free radical scavenging activity (FRSA), polyphenolic contents and flavonoid contents in the paper. The results showed the extracts of Paeonia suffruticosa Andr., Paeonia lactiflora Pall., and Rosa rugosa Thunb. possessed obviously stronger DPPH FRSA (94.221 ± 0.102; 93.739 ± 0.424 and 94.244 ± 0.163%, respectively), superoxide FRSA (55.818 ± 1.518; 52.142 ± 1.374 and 57.321 ± 0.608%, respectively), hydroxyl FRSA (85.872 ± 0.873; 89.307 ± 0.803 and 88.560 ± 0.277%, respectively) and polyphenolic contents (96.208 ± 0.689; 87.938 ± 1.187 and 92.164 ± 0.799 mg CE/g, respectively) that were superior or comparable to black and green teas. Polyphenolic contents did correlate well with DPPH FRSA (r = 0.943, P < 0.01), superoxide FRSA (r = 0.833, P < 0.01), and hydroxyl FRSA (r = 0.500, P < 0.05). It indicated that this potent FRSA may be attributed to its phenolic compounds. These findings showed that the tested flowers could be considered as new sources of safe natural antioxidants and preservatives of food industry.

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Microorganisms play an important role in the biodegradation of petroleum contaminants, which have attracted great concern due to their persistent toxicity and difficult biodegradation. In this paper, a novel hydrocarbon-degrading bacterium HZ01 was isolated from the crude oil-contaminated seawater at the Daya Bay, South China Sea, and identified as Achromobacter sp. Under the conditions of pH 7.0, NaCl 3% (w/v), temperature 28 °C and rotary speed 150 rpm, its degradability of the total n-alkanes reached up to 96.6% after 10 days of incubation for the evaporated diesel oil. Furthermore, Achromobacter sp. HZ01 could effectively utilize polycyclic aromatic hydrocarbons (PAHs) as its sole carbon source, and could remove anthracene, phenanthrene and pyrence about 29.8%, 50.6% and 38.4% respectively after 30 days of incubation. Therefore, Achromobacter sp. HZ01 may employed as an excellent degrader to develop one cost-effective and eco-friendly method for the bioremediation of marine environments polluted by crude oil.

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The biodetoxification of cyanide-rich wastewater has become increasingly popular because of its cost-effectiveness and environmental friendliness. Therefore, we have developed an effective method, optimised by response surface methodology, for detoxifying cyanide-rich wastewater using Bacillus sp. CN-22, which was newly isolated from a cyanide-contaminated electroplating sludge and could tolerate a CN⁻ concentration of 700 mg L⁻¹. The concentration of CN⁻ in the treated wastewater decreased from 200 to 6.62 mg L⁻¹ after cultivation with 2.38 % inocula for 72 h on the medium, consisting of 0.05 % KH2PO4, 0.15 % K2HPO4, 1.0 mM MgCl2, 1.0 mM FeCl3, 0.1 % NH4Cl, and 0.1 % glycerol. The CN⁻ degradability of 96.69 % is similar to the predicted value of 96.82 %. The optimal cultivation conditions were controlled as follows: initial pH, 10.3; temperature, 31 °C; and rotary speed, 193 rpm. The maintenance of higher pH in the overall treatment procedures may avoid the production of volatile HCN and the risk associated with cyanide detoxification. Additionally, the bacterial strain Bacillus sp. CN-22, with its potent cyanide-degrading activity at the initial CN⁻ concentration of 200 mg L⁻¹, may be employed to effectively treat cyanide-rich wastewater, especially electroplating effluent.

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Statistically based experimental designs were applied to optimize the fermentation medium and cultural conditions for the maximization of neutral protease using three agroindustrial residues (cassava pulp, soybean meal, and wheat bran) and Bacillus subtilis DES-59. The Plackett-Burman design was used to evaluate the effects of variables such as the concentration of substrates, initial pH, shaker's rotating speed, temperature, inoculum size, and incubation time. Among the eight parameters, three significant variables (cassava pulp, soybean meal, and inoculum size) were selected for the optimization study, in which a central composite design was used to optimize the concentrations of cassava pulp and soybean meal and inoculum size and investigate the interactive effects of the three variables. The optimal parameters obtained from response surface methodology are 37.78 g/L of cassava pulp, 15 g/L of soybean meal, and 6.5% (v/v) of inoculum size, respectively, resulting in a maximum neutral protease activity of 4107 ± 122 U/mL.

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