Axially slow-variation microbubble resonators fabricated by an improved arc discharge method for strain sensing applications.

In this paper, we proposed an axially slow-variation microbubble resonator fabricated by an improved arc discharge method and applied to axial strain sensing. The prepared resonators are characterized by ultra-thin wall thickness and axial slow-variation. The wall thickness was experimentally measured to reach 938 nm and maintain a quality factor of an optical mode as large as 7.36 ×107. The main factors affecting the strain sensitivity of the microbubble resonators are investigated theoretically and experimentally. Experimentally, the maximum sensitivity measured was 13.08pm/µÎµ, which is three times higher than the microbubble resonators without this method. The device is simple to prepare and possesses ultra-thin wall thickness. It is promising for applications in high-precision sensing, such as single molecule and biological sensing.

Cascaded stimulated Brillouin laser and Brillouin-Kerr optical frequency comb in high-Q MgF2 disk resonators.

Backward stimulated Brillouin scattering (SBS) in optical microcavities has been widely used in nonlinear optics and microwave photonics. Compared with glass material microcavity, magnesium fluoride crystal microcavity has the advantages of small absorption coefficient, fewer defects and larger nonlinear coefficient, moreover, it usually has a narrow gain bandwidth of tens of megahertz. Here, we design a high precision machining system to produce ultra-smooth surface magnesium fluoride crystal disk cavities with a diameter of about 5 mm, Q value exceeding 108, FSR matching material Brillouin gain. By simply modulating the pump wavelength and coupling power, we observe SBS phenomena with a 13.47 GHz Brillouin frequency shift near 1.55µm and cascaded stimulated Brillouin lasers (SBL) of up to 12 orders. In addition, the Brillouin-Kerr optical frequency comb in this device is demonstrated, observing nearly 300 comb lines spanning across a spectral window of 250 nm. Our research provides a way to fabricate high-Q crystal microcavities and demonstrates the potential of these devices in applications such as microwave sources and nonlinear optics.

Comparative genomic analysis of the genus Weissella and taxonomic study of Weissella fangxianensis sp. nov., isolated from Chinese rice wine starter.

In this study, three lactic acid bacteria, namely, HBUAS51963T, HBUAS51964 and HBUAS51965, were isolated from Chinese rice wine starter sampled in Fangxian County, PR China. All were non-motile, non-spore-forming and Gram-positive spherical cells. Their taxonomic status was characterized using a polyphasic approach. Genome-based analysis revealed that all three strains were phylogenomically related to Weissella thailandensis KCTC 3751T and Weissella paramesenteroides ATCC 33313T. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the three strains and the phylogenetically related type strains were less than 54.8 and 93.8 %, respectively, and thus, they were below the thresholds of dDDH and ANI for species definition. The genomic DNA G+C content was 38.6 mol %. The predominant fatty acid methyl esters (>10 %) were C16 : 0, C19 : 0 cyc11 and summed feature 10 (C18 : 1 cyc11 and/or ECL 17.834). The polar lipids in the cells of strain HBUAS51963T were mainly phosphatidylglycerol, diphosphatidylglycerol, unidentified glycolipids, phospholipids and lipids. Finally, the three strains were capable of producing d-lactic acid (4.29 g l-1) and various organic acids such as tartaric, acetic, lactic and succinic acids. Overall, the results of genotypic, phenotypic and genomic analyses suggest that the three strains represent a new species of the genus Weissella, for which the name Weissella fangxianis sp. nov. is proposed. The type strain is HBUAS51963T (=GDMCC 1.3506T= JCM 35803T).

Activated carbon enhanced traditional activated sludge process for chemical explosion accident wastewater treatment.

With the development of industries, explosion accidents occur frequently during production, transportation, usage and storage of hazard chemicals. It remained challenging to efficiently treat the resultant wastewater. As an enhancement of traditional process, the activated carbon-activated sludge (AC-AS) process has a promising potential in treating wastewater with high concentrations of toxic compounds, chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N), etc. In this paper, activated carbon (AC), activated sludge (AS) and AC-AS were used to treat the wastewater produced from an explosion accident in the Xiangshui Chemical Industrial Park. The removal efficiency was assessed by the removal performances of COD, dissolved organic carbon (DOC), NH4+-N, aniline and nitrobenzene. Increased removal efficiency and shortened treatment time were achieved in the AC-AS system. To achieve the same COD, DOC and aniline removal (90%), the AC-AS system saved 30, 38 and 58 h compared with the AS system, respectively. The enhancement mechanism of AC on the AS was explored by metagenomic analysis and three-dimensional excitation-emission-matrix spectra (3DEEMs). More organics, especially aromatic substances were removed in the AC-AS system. These results showed that the addition of AC promoted the microbial activity in pollutant degradation. Bacteria, such as Pyrinomonas, Acidobacteria and Nitrospira and genes, such as hao, pmoA-amoA, pmoB-amoB and pmoC-amoC, were found in the AC-AS reactor, which might have played important roles in the degradation of pollutants. To sum up, AC might have enhanced the growth of aerobic bacteria which further improved the removal efficiency via the combined effects of adsorption and biodegradation. The successful treatment of Xiangshui accident wastewater using the AC-AS demonstrated the potential universal characteristics of the process for the treatment of wastewater with high concentration of organic matter and toxicity. This study is expected to provide reference and guidance for the treatment of similar accident wastewaters.

Two-dimensional displacement estimation of one-dimensional laser speckle images for detection of acoustic vibration.

Detection and recovery of audio signals using optical methods is an appealing topic. Observing the movement of secondary speckle patterns is a convenient method for such a purpose. In order to have less computational cost and faster processing, one-dimensional laser speckle images are captured by an imaging device, while it sacrifices the ability to detect speckle movement along one axis. This paper proposes a laser microphone system to estimate the two-dimensional displacement from one-dimensional laser speckle images. Hence, we can regenerate audio signals in real time even as the sound source is rotating. Experimental results show that our system is capable of reconstructing audio signals under complex conditions.

Levilactobacillus yiduensis sp. nov., Isolated from Zha-chili in Yidu County, Hubei Province, China.

The zha-chili isolate HBUAS62285T is a facultative anaerobic strain. This bacterium was gram-positive, but it could not generate catalase, was not motile, did not form spores, had no flagella, and produced gamma-aminobutyric acid (GABA). Comparing of HBUAS62285T with its related type strains Levilactobacillus suantsaiihabitans BCRC 81129T, Levilactobacillus angrenensis M1530-1T, Levilactobacillus cerevisiae DSM 100836T, Levilactobacillus wangkuiensis 6-5(1)T, Levilactobacillus lanxiensis 13B17T, and Levilactobacillus mulengensis 112-3T showed that the similarity of 16S rRNA gene sequence was less than 99.13%. Strain HBUAS62285T has a G+C content of 50.57 mol%, an ANI value of less than 86.61%, an AAI value of less than 92.9%, and a dDDH value of less than 32.9% when compared to the aforementioned closely related strains. In the end, the most major fatty acids in cells were determined to be C16:0, C18:1 ω9c, C19:1 cyclo ω9,10c, and summed feature 10. Overall, the results of the phenotypic, genomic, chemotaxonomic, and phylogenetic studies indicate that strains HBUAS62285T and CD0817 constitute a new species within the genus Levilactobacillus, and the name Levilactobacillus yiduensis sp. nov. is proposed. The type strain is HBUAS62285T (= JCM 35804T = GDMCC 1.3507T).

Ultra-high-depth macrogenomic sequencing revealed differences in microbial composition and function between high temperature and medium-high temperature Daqu.

Complex microorganisms in Daqu of different temperatures play a vital role in the taste, flavor and quality of Baijiu during fermentation. However, understanding the functional diversity of the whole microbial community between the Daqus of two different temperatures (high temperature Daqu, HD and medium-high temperature Daqu, MD) remains a major challenge. Here, a systematic study of the microbial diversity, functions as well as physiological and biochemical indexes of Daqu are described. The results revealed that the Daqu exhibited unique characteristics. In particular, the diversity of microorganisms in HD and MD was high, with 44 species including 14 novel species (Sphingomonas sp. is the main novel species) detected in all samples. Their profiles of carbohydrate-active enzymes and specific functional components supported the fact that these species were involved in flavor formation. The Daqu microbiome consisted of a high proportion of phage, providing evidence of phage infection/genome integration and horizontal gene transfer from phage to bacteria. Such processes would also regulate Daqu microbiomes and thus flavor quality. These results enrich current knowledge of Daqu and can be used to promote the development of Baijiu fermentation technology.

[Traditional Chinese medicine microbiomics and its research strategies].

The tight relationships between microbiome and traditional Chinese medicine(TCM)have been widely recognized. New technologies, results, and theories are emerging in the field of microbiomics in recent years with the advances in high-throughput sequencing and multi-omics technologies. Based on the previous research, the present study has proposed the concept of TCM microbiomics(TCMM), which is an interdisciplinary subject aiming at elucidating the functions and applications of microbiome in the areas of herb resources, herb processing, herb storage, and clinical effects by using modern technology of biology, ecology, and informatics. This subject essentially contains the structures, functions, interactions, molecular mechanisms, and application strategies of the microbiome associated with the quality, safety, and efficacy of TCM. Firstly, the development of the TCMM concept was summarized, with the profound understanding of TCMM on the complexity and entirety of microbiome being emphasized. Then, the research contents and applications of TCMM in promoting the sustainable development of herb resources, improving the standardization and diversification of herb fermentation, strengthening the safety of herb storage, and resolving the scientific connotation of theories and clinical efficacy of TCM are reviewed. Finally, the research strategies and methods of TCM microbiomics were elaborated from basic research, application research, and system research. TCMM is expected to promote the integrative development of TCM with frontier science and technology, thereby expanding the depth and scope of TCM study and facilitating TCM modernization.

[Research summary of chemical constituents and pharmacological effects of Panax notoginseng and predictive analysis on its Q-markers].

Panax notoginseng contains triterpene saponins, flavonoids, amino acids, polysaccharides, volatile oil and other active components, which have the effects of promoting blood circulation, stopping bleeding, removing blood stasis, etc. This study summarized the herbal research, chemical constituents and main pharmacological activities of P. notoginseng, and based on the theory of Q-markers of traditional Chinese medicine, predicted and analyzed the Q-markers of P. notoginseng from the aspects of plant kinship, efficacy, drug properties, measurability of chemical components, etc. It was found that ginsenosides Rg_1, Re, and Rb_1 with specific content ratio, ginsenosides Rb_2, Rb_3, Rc, Rd, Rh_2, and Rg_3, notoginseng R_1, dencichine and quercetin could be used as potential Q-markers of P. notoginseng, which facilitated the formulation of quality standards reflecting the efficacy of P. notoginseng.

Analysis of bacterial diversity and genetic evolution of Lacticaseibacillus paracasei isolates in fermentation pit mud.

AIMS: Since little is known about the genetic diversity of lactic acid bacteria (LAB) isolates from the fermentation pit mud (FPM), we sought to evaluate the bacterial structure, identify the LAB isolates and investigate the genotype and genetic diversity of the LAB isolates. METHODS AND RESULTS: Using high-throughput MiSeq sequencing, we identified seven dominant bacterial genera in FPM. Lactobacillus had the highest abundance. We isolated 55 LAB strains. These isolates were all identified as Lacticaseibacillus paracasei. Using an extant multilocus sequence typing (MLST) scheme, isolates were assigned to 18 sequence types (STs) and three clonal complexes. ST1, the largest group, mainly comprised FPM isolates. Niche-specific ST2 to ST18 only contained FPM isolates. Isolates could be divided into four lineages, with most assigned to Lineage 1. Only one FPM isolate was classified as L. paracasei subsp. paracasei. Other isolates could not be classified at the subspecies level using the seven MLST loci. CONCLUSIONS: Lactobacilli account for a high proportion of bacteria in pit mud. Based on the traditional culture method, L. paracasei was the dominant species, and these isolates exhibit a high ethanol tolerance, high intraspecific diversity and specific genetic profiles. SIGNIFICANCE AND IMPACT OF THE STUDY: The study described the characterization of FPM bacterial diversity, giving an insight into the genetic diversity of L. paracasei strains present in FPM.

Fungal Diversity in Xinjiang Traditional Cheese and its Correlation With Moisture Content.

Cheese is one of the traditional fermented dairy products in Xinjiang, China. Due to its geographical location and regional feature this type of cheese harbors certain regional characteristics. To investigate these, here Illumina MiSeq high-throughput sequencing technology was used to target the v4-v5 interval to analyze the composition of fungal flora in Xinjiang traditional cheese. Our results showed the fungal flora of this cheese is mainly composed of Pichia (65.20%), Kazachstania (9.05%), Galactomyces (7.21%), Zygosaccharomyces (6.56%), Torulaspora (3.13%), Dipodascus (2.11%) and Ogataea (1.64%) belonging to the Ascomycota. PcoA (Principal Co-ordinates Analysis) and an UPGMA (unweighted pair-group method with arithmetic means) based on the OTUs (Optical Transform Unit) horizontal-weighted UniFrac distances, revealed some differences in fungal community structure among 17 cheese samples. At the OTU level, nine dominant OTUs were found in all the samples, for which Pichia was the most important fungal group. Building on this, the moisture content (23.20-59.22%), water distribution, and salt content (1.13-4.84%) in cheese were also determined. We found that six of the seven dominant fungal genera had specific correlations with the above physical and chemical variables, with only Ogataea uncorrelated with any variables. The results provide a theoretical basis for the development and use of cheese microbial resources in Xinjiang, China. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-021-00967-x.

The diversity and composition of the human gut lactic acid bacteria and bifidobacterial microbiota vary depending on age.

Aging is associated with gut microbiota alterations, characterized by changes in intestinal microbial diversity and composition. However, no study has yet focused on investigating age-related changes in the low-abundant but potentially beneficial subpopulations of gut lactic acid bacteria (LAB) and Bifidobacterium. Our study found that the subjects' age correlated negatively with the alpha diversity of the gut bifidobacterial microbiota, and such correlation was not observed in the gut LAB subpopulation. Principal coordinate analysis (PCoA) and analysis of distribution of operational taxonomic units (OTUs) revealed that the structure and composition of the gut bifidobacterial subpopulation of the longevous elderly group were rather different from that of the other three age groups. The same analyses were applied to identify age-dependent characteristics of the gut LAB subpopulation, and the results revealed that the gut LAB subpopulation of young adults was significantly different from that of all three elderly groups. Our study identified several potentially beneficial bacteria (e.g., Bifidobacterium breve and Bifidobacterium longum) that were enriched in the longevous elderly group (P < 0.05), and the relative abundance of Bifidobacterium adolescentis decreased significantly with the increase in age (P < 0.05). Although both bifidobacteria and LAB are generally considered as health-promoting taxa, their age-dependent distribution varied from each other, suggesting their different life stage changes and potentially different functional roles. This study provided novel species-level gut bifidobacterial and LAB microbiota profiles of a large cohort of subjects and identified several age-or longevity-associated features and biomarkers. KEY POINTS: • The alpha diversity of the gut bifidobacterial microbiota decreased with age, while LAB did not change. • The structure and composition of the gut bifidobacterial subpopulation of the longevous elderly group were rather different from that of the other three age groups. • Several potentially beneficial bacteria (e.g., Bifidobacterium breve and Bifidobacterium longum) that were enriched in the longevous elderly group.

Identification of chemical constituents in vitro and in vivo of Er Shen Zhenwu Decoction by utilizing ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

Er Shen Zhenwu Decoction is a prescription for treating chronic heart failure of heart and kidney yang deficiency, while its active ingredients remain unclear and difficult to identify. This paper aims to apply a rapid assay strategy of ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry to collect the mass spectrometry data of Er Shen Zhenwu Decoction and its decomposed recipes (monarch, minister, and assist). By comparing with retention time and MSE fragmentation patterns, 67 and 34 components in vitro and in vivo were identified, respectively, the main ingredients include saponins, terpenes, alkaloids, phenolic acids, tanshinone, urea, steroids, aromatics, organic acids, carbohydrates, and so forth, of which the monarch medicine > minister medicine > assist medicine. By comparison with reference standards, paeoniflorin, rosmarinic acid, ginsenoside Rg1, ginsenoside Re, ginsenoside Rb1 and atractylenolide III were identified in vitro and paeoniflorin, ginsenoside Rg1, ginsenoside Re and ginsenoside Rb1 were identified in vivo. In this study, the chemical ingredients of Er Shen Zhenwu Decoction were analyzed by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry technology and each compound was grouped into the decomposed recipes. The identified substances can be used as references for Er Shen Zhenwu Decoction quality control and potential medicinal substances in chronic heart failure of heart and kidney yang deficiency treatment.

Integrated Succinylome and Metabolome Profiling Reveals Crucial Role of S-Ribosylhomocysteine Lyase in Quorum Sensing and Metabolism of Aeromonas hydrophila.

Protein modification by lysine succinylation is a newly identified post-translational modification (PTM) of lysine residues and plays an important role in diverse physiological functions, although their associated biological characteristics are still largely unknown. Here, we investigated the effects of lysine succinylation on the physiological regulation within a well-known fish pathogen, Aeromonas hydrophila A high affinity purification method was used to enrich peptides with lysine succinylation in A. hydrophila ATCC 7966, and a total of 2,174 lysine succinylation sites were identified on 666 proteins using LC-MS/MS. Gene ontology analysis indicated that these succinylated proteins are involved in diverse metabolic pathways and biological processes, including translation, protein export, and central metabolic pathways. The modifications of several selected candidates were further validated by Western blotting. Using site-directed mutagenesis, we observed that the succinylation of lysines on S-ribosylhomocysteine lyase (LuxS) at the K23 and K30 sites positively regulate the production of the quorum sensing autoinducer AI-2, and that these PTMs ultimately alter its competitiveness with another pathogen, Vibrio alginolyticus Moreover, subsequent metabolomic analyses indicated that K30 succinylation on LuxS may suppress the activated methyl cycle (AMC) and that both the K23 and K30 sites are involved in amino acid metabolism. Taken together, the results from this study provide significant insights into the functions of lysine succinylation and its critical roles on LuxS in regulating the cellular physiology of A. hydrophila.

Full-field laser heterodyne imaging vibrometry using a CMOS-DVR system.

A laser heterodyne imaging vibrometry is proposed for full-field vibration measurement. The vibration responses are imaged and recorded using a CMOS camera and a digital video recorder. A digital demodulation method based on a cumulative distribution function and autocorrelation is designed to demodulate signals affected by speckle noise. The experimental investigations confirm the viability of the proposed method for vibration measurement. Meanwhile, a comparison with laser Doppler vibrometry is performed to further validate the method. The results prove the proposed vibrometry is an effective and precise option for full-field vibration measurement.

Bacterial Diversity in Pickled Cowpea (Vigna unguiculata [Linn.] Walp) as Determined by Illumina MiSeq Sequencing and Culture-Dependent Methods.

Pickled cowpea (Vigna unguiculata [Linn.] Walp) is a popular fermented vegetable in China that is made by spontaneous fermentation. Prior to this study, little was known about its microbial community. Eighteen pickled cowpea samples were collected in Enshi City, China, in 2018. The bacterial diversity within these samples was evaluated using a combination of high-throughput sequencing (Illumina MiSeq platform) targeting the V3-V4 region of the 16S rRNA gene sequence and culture-dependent methods. A total of 456,318 high-quality 16S rRNA gene sequence reads were obtained, and these reads were clustered into 19,712 OTUs with 97.0% similarity. The core bacterial phyla were Actinobacteria, Bacteroidetes, Proteobacteria, and Firmicutes; the core bacterial genera were Levilactobacillus, Lactiplantibacillus, Companilactobacillus, Pediococcus, Lactobacillus, Weissella, and Pseudomonas. Using the spread-plating method, 39 lactic acid bacteria (LAB) strains were isolated and identified based on the nearly complete 16S rRNA gene sequence. Of these, 37 were identified as Lactiplantibacillus plantarum group, while the other two were classified as Limosilactobacillus fermentum and Lacticaseibacillus rhamnosus. These results indicate a high relative abundance of LAB in traditional pickled cowpea, especially Lactobacillaceae species, which likely contribute to fermentation. This study would provide information on the LAB population of Pickled cowpea and indicated that the Pickled cowpea could be a good source for isolation of lactic acid bacteria.

The type II phosphoinositide 4-kinase FgLsb6 is important for the development and virulence of Fusarium graminearum.

Fusarium graminearum is the main pathogenic fungus causing Fusarium head blight (FHB), which is a wheat disease with a worldwide prevalence. In eukaryotes, phosphatidylinositol 4-phosphate (PI4P), which participates in many physiological processes, is located primarily in different organelles, including the trans-Golgi network (TGN), plasma membrane and endosomes. Type II phosphatidylinositol 4-kinases (PI4Ks) are involved in regulating the production of PI4P in yeast, plants and mammalian cells. However, the role of these proteins in phytopathogenic fungi is not well understood. In this study, we characterized the type II PI4K protein FgLsb6 in F. graminearum, a homolog of Lsb6 in Saccharomyces cerevisiae. Unlike Lsb6, FgLsb6 localizes to the vacuoles and endosomes. The ΔFglsb6 mutant displayed defects in vegetative growth, deoxynivalenol (DON) production and pathogenicity. Furthermore, the ΔFglsb6 deletion mutant also exhibited increased resistance to osmotic, oxidative and cell wall stresses. Further analyses of the ΔFglsb6 mutant showed that it was defective in the generation of PI4P on endosomes and endocytosis. Collectively, our data suggest that the decreased vegetative growth and pathogenicity of ΔFglsb6 was due to the conservative roles of FgLsb6 in the generation of PI4P on endosomes and endocytosis.

Lactobacillus enshiensis sp. nov., a novel arsenic-resistant bacterium.

A lactic acid bacterial strain, HBUAS57009T, isolated from traditionally fermented food (Zha-Chili) in China, was characterized to clarify its taxonomic status using a polyphasic approach. Strain HBUAS57009T was phylogenetically closely related to Lactobacillus koreensis DCY50T, Lactobacillus fujinensis 218-6T, Lactobacillus mulengensis 112-3T, Lactobacillus cerevisiae TUM BP 140423000-2250T, Lactobacillus tongjiangensis 218-10T and Lactobacillus yonginensis THK-V8T with sequence similarities of 98.6-99.3 %. The genome-to-genome distance and average nucleotide identity values between the genomes of strain HBUAS57009T and type strains of closely related Lactobacillus species were less than 32.0 and 86.0 %, respectively; this is below the threshold for species boundaries. The major cellular fatty acids (>10 %) were C16 : 0, C18 : 1 ω9c and iso-C19 : 0. The G+C content of the genomic DNA of strain HBUAS57009T was 47.8 mol%. Examination of the functional categories of the genome revealed that strain HBUAS57009T could perform both homolactic and heterolactic fermentation processes to produce lactic acid via complete glycolysis and the pentose phosphate pathway. The putative biosynthesis pathway of butane-2,3-diol and acetoin, two important flavour compounds in the food industry, were identified using kegg mapper analysis. Based on its genotypic and phenotypic features, strain HBUAS57009T (=GDMCC 1.1664T=KACC 21424T) is designated as the type strain of a novel species, for which the name Lactobacillus enshiensis sp. nov. is proposed.

High-throughput Sequencing-based Analysis of Microbial Diversity in Rice Wine Koji from Different Areas.

Rice wine, a traditional fermented alcoholic beverage in China, is produced with grains such as rice, which are fermented with saccharifying starter-koji. Its flavor quality is closely associated to the starter culture-koji, which is made by mixing botanical materials with high-class glutinous rice in certain ecological context. However, there are few reports on the microbial community structure of rice wine koji. In this paper, bacterial community structures of rice wine koji were analyzed using 16S rRNA gene sequencing based on Illumina MiSeq high-throughput technology in 20 samples collected from Xiaogan area, Hubei province and Dazhu area, Sichuan province (10 from each area). We found rice wine koji flora mainly consisted of Weissella, Lactobacillus, Lactococcus, Bacillus, Enterococcus, and Cronobacter, with relative abundances of 29.49%, 10.93%, 8.85%, 4.75%, 1.16% and 1.15%, respectively, as well as an accumulative average relative abundance of 58.71%. They all belonged to Firmicutes and Proteobacteria-the two known dominant genus. Genus-level PCA (Principal component analysis) and OTU-level PCoA (Principal coordinates analysis) based on unweighted UniFrac distances showed that the bacterial community structure differed significantly between the samples from the 2 areas. 7 OTUs were detected in all samples, accounting for 4.4% of the total qualified assembly. Among the 7 OTUs, 3 OTUs were identified as Enterococcus, 2 OTUs were identified as Cronobacter, 1 OTU was identified as Bacillus and 1 OTU was identified as Alkaliphilus. Fifty-eight lactic acid bacteria (LAB) strains were isolated from the 20 koji samples with traditional microbial methods. Among them, Enterococcus faecium and Pediococcus pentosaceus were the dominant LAB isolates, with relative abundances of 51.72% and 31.03%. Despite the differences, a large number of shared bacteria were detected in samples from the two areas.

Single-Atom Mn-N4 Site-Catalyzed Peroxone Reaction for the Efficient Production of Hydroxyl Radicals in an Acidic Solution.

The peroxone reaction between O3 and H2O2 has been deemed a promising technology to resolve the increasingly serious water pollution problem by virtue of the generation of superactive hydroxyl radicals (•OH), but it suffers greatly from an extremely limited reaction rate constant under acidic conditions (ca. less than 0.1 M-1 s-1 at pH 3). This article describes a heterogeneous catalyst composed of single Mn atoms anchored on graphitic carbon nitride, which effectively overcomes such a drawback by altering the reaction pathway and thus dramatically promotes •OH generation in acid solution. Combined experimental and theoretical studies demonstrate Mn-N4 as the catalytically active sites. A distinctive catalytic pathway involving HO2• formation by the activation of H2O2 is found, which gets rid of the restriction of HO2- as the essential initiator in the conventional peroxone reaction. This work offers a new pathway of using a low-cost and easily accessible single-atom catalyst (SAC) and could inspire more catalytic oxidation strategies.