Semiautomated design and soluble expression of a chimeric antigen TbpAB01 from Glaesserella parasuis.

Pathogenic bacterial membrane proteins (MPs) are a class of vaccine and antibiotic development targets with widespread clinical application. However, the inherent hydrophobicity of MPs poses a challenge to fold correctly in living cells. Herein, we present a comprehensive method to improve the soluble form of MP antigen by rationally designing multi-epitope chimeric antigen (ChA) and screening two classes of protein-assisting folding element. The study uses a homologous protein antigen as a functional scaffold to generate a ChA possessing four epitopes from transferrin-binding protein A of Glaesserella parasuis. Our engineered strain, which co-expresses P17 tagged-ChA and endogenous chaperones groEL-ES, yields a 0.346 g/L highly soluble ChA with the property of HPS-positive serum reaction. Moreover, the protein titer of ChA reaches 4.27 g/L with >90% soluble proportion in 5-L bioreactor, which is the highest titer reported so far. The results highlight a timely approach to design and improve the soluble expression of MP antigen in industrially viable applications.

A Free Amino Acid Diet Alleviates Colorectal Tumorigenesis through Modulating Gut Microbiota and Metabolites.

Colorectal cancer (CRC), a major global health concern, may be influenced by dietary protein digestibility impacting gut microbiota and metabolites, which is crucial for cancer therapy effectiveness. This study explored the effects of a casein protein diet (CTL) versus a free amino acid (FAA)-based diet on CRC progression, gut microbiota, and metabolites using carcinogen-induced (AOM/DSS) and spontaneous genetically induced (ApcMin/+ mice) CRC mouse models. Comprehensive approaches including 16s rRNA gene sequencing, transcriptomics, metabolomics, and immunohistochemistry were utilized. We found that the FAA significantly attenuated CRC progression, evidenced by reduced colonic shortening and histopathological alterations compared to the CTL diet. Notably, the FAA enriched beneficial gut bacteria like Akkermansia and Bacteroides and reversed CRC-associated dysbiosis. Metabolomic analysis highlighted an increase in ornithine cycle metabolites and specific fatty acids, such as Docosapentaenoic acid (DPA), in FAA-fed mice. Transcriptomic analysis revealed that FAA up-regulated Egl-9 family hypoxia inducible factor 3 (Egln 3) and downregulated several cancer-associated pathways including Hippo, mTOR, and Wnt signaling. Additionally, DPA was found to significantly induce EGLN 3 expression in CRC cell lines. These results suggest that FAA modulate gut microbial composition, enhance protective metabolites, improve gut barrier functions, and inhibit carcinogenic pathways.

Enhanced synthesis of S-adenosyl-L-methionine through combinatorial metabolic engineering and Bayesian optimization in Saccharomyces cerevisiae.

S-Adenosyl-L-methionine (SAM) is a substrate for many enzyme-catalyzed reactions and provides methyl groups in numerous biological methylations, and thus has vast applications in the agriculture and medical field. Saccharomyces cerevisiae has been engineered as a platform with significant potential for producing SAM, but the current production has room for improvement. Thus, a method that consists of a series of metabolic engineering strategies was established in this study. These strategies included enhancing SAM synthesis, increasing ATP supply, down-regulating SAM metabolism, and down-regulating competing pathway. After combinatorial metabolic engineering, Bayesian optimization was conducted on the obtained strain C262P6S to optimize the fermentation medium. A final yield of 2972.8 mg·L-1 at 36 h with 29.7% of the L-Met conversion rate in the shake flask was achieved, which was 26.3 times higher than that of its parent strain and the highest reported production in the shake flask to date. This paper establishes a feasible foundation for the construction of SAM-producing strains using metabolic engineering strategies and demonstrates the effectiveness of Bayesian optimization in optimizing fermentation medium to enhance the generation of SAM.

[Metagenomics unveils the differences in the functions of microbial community of medium-temperature Daqu before and after maturation].

Daqu is the saccharifying, fermenting, and aroma-producing agent used in Baijiu brewing, and its maturation is crucial for obtaining high-quality Daqu. Previous studies have explored the microbial community composition and diversity before and after maturation. However, little is known about the changes in the functions of microbial community. In this study, based on the analyses of enzyme activities and volatile compounds of medium-temperature Daqu before and after maturation, metagenomics was used to analyze the differences in the composition of microbial community and the potential functions, with the aim to explore the microorganisms involved in changes in enzyme activities and important volatiles. The results showed that the moisture (P≤0.05), starch content, liquefying activity, saccharifying activity (P≤0.05), and fermentative activity decreased, while the acidity and esterifying activity (P≤0.05) increased after Daqu maturation. In the meantime, the composition of volatile compounds changed significantly (P=0.001), with significant decreases in the contents of aromatic alcohols and esters as well as significant increases in the contents of pyrazines, ketones, and higher fatty alcohols. The relative abundances of Mucorales (34.8%-23.0%) and Eurotiales (34.3%-20.1%) decreased in matured Daqu, and functional predictions showed these changes decreased the gene abundances of α-amylase, α-glucosidase, alcohol dehydrogenase, and alcohol dehydrogenase (NADP+) (P > 0.05), resulting in lower levels of liquefying activity (P > 0.05), saccharifying activity (P≤0.05), fermentative activity (P > 0.05), as well as aromatic alcohols such as phenylethyl alcohol (P≤0.05). In addition, higher relative abundances of Saccharomycetales (2.9%-16.6%), Lactobacillales (14.9%-23.6%), and Bacillales (0.8%-3.8%) were observed after maturation, and they were conducive to improving the gene abundances of alcohol O-acetyltransferase, carboxylesterase, acetolactate decarboxylase, (R)-acetoin dehydrogenase, and (S)-acetoin dehydrogenase (P≤0.05), resulting in significantly higher levels of esterifying activity and pyrazines (P≤0.05). The microorganisms involved in the changes in enzyme activities and important volatiles before and after Daqu maturation were studied at the gene level in this work, which may facilitate further rational regulation for Daqu production.

Rapid detection of six Oceanobacillus species in Daqu starter using single-cell Raman spectroscopy combined with machine learning.

Many traditional fermented foods and beverages industries around the world request the addition of multi-species starter cultures. However, the microbial community in starter cultures is subject to fluctuations due to their exposure to an open environment during fermentation. A rapid detection approach to identify the microbial composition of starter culture is essential to ensure the quality of the final products. Here, we applied single-cell Raman spectroscopy (SCRS) combined with machine learning to monitor Oceanobacillus species in Daqu starter, which plays crucial roles in the process of Chinese baijiu. First, a total of six Oceanobacillus species (O. caeni, O. kimchii, O. iheyensis, O. sojae, O. oncorhynchi subsp. Oncorhynchi and O. profundus) were detected in 44 Daqu samples by amplicon sequencing and isolated by pure culture. Then, we created a reference database of these Oceanobacillus strains which correlated their taxonomic data and single-cell Raman spectra (SCRS). Based on the SCRS dataset, five machine-learning algorithms were used to classify Oceanobacillus strains, among which support vector machine (SVM) showed the highest rate of accuracy. For validation of SVM-based model, we employed a synthetic microbial community composed of varying proportions of Oceanobacillus species and demonstrated a remarkable accuracy, with a mean error was less than 1% between the predicted result and the expected value. The relative abundance of six different Oceanobacillus species during Daqu fermentation was predicted within 60 min using this method, and the reliability of the method was proved by correlating the Raman spectrum with the amplicon sequencing profiles by partial least squares regression. Our study provides a rapid, non-destructive and label-free approach for rapid identification of Oceanobacillus species in Daqu starter culture, contributing to real-time monitoring of fermentation process and ensuring high-quality products.

High-Level Extracellular Expression of Hyaluronate Lyase HylP in Bacillus subtilis for Hyaluronan Degradation.

Hyaluronate lyase (HA lyase) has potential in the industrial processing of hyaluronan. In this study, HylP, an HA lyase from Streptococcus pyogenes phage (SPB) was successfully expressed in Bacillus subtilis. To improve the extracellular enzyme activity of HylP in B. subtilis, signal peptide engineering systematic optimization was carried out, and cultured it from shake flasks and fermenters, followed by purification, characterization, and analysis of degradation products. The results showed that the replacement of the signal peptide increased the extracellular enzyme activity of HylP from 1.0 × 104 U/mL to 1.86 × 104 U/mL in the shake flask assay, and using a 20 L fermenter in a batch fermentation process, the extracellular enzyme activity achieved the level of 1.07 × 105 U/mL. HylP exhibited significant thermal and pH stability in the temperature range of 40 °C and pH range of 4-8, respectively. The enzyme showed optimum activity at 40 °C and pH 6, with significant activity in the presence of Na+, Mg2+, and Co2+ ions. Degradation analysis showed that HylP efficiently degraded hyaluronan as an endonuclease, releasing unsaturated disaccharides. These comprehensive findings underscore the substantial industrial potential of HylP for hyaluronan processing applications, offering valuable insights into enzyme characterization and optimization of expression for potential industrial utilization.

Enhanced Production of Sisomicin in Micromonospora inyoensis by Protoplast Mutagenesis and Fermentation Optimization.

Sisomicin is a broad-spectrum aminoglycoside antibiotic and is the precursor of netilmicin and plazomicin. However, the fermentation level of sisomicin is still low compared with other antibiotics, which restricts the application of sisomicin and its derivatives. In this study, to improve sisomicin production, breeding of high-yielding sisomicin strains was conducted with chemical mutagenesis using Micromonospora inyoensis OG-1 (titer, 1042 U·mL-1) as the starting strain. Protoplast preparation was conducted under optimal conditions, and protoplast mutagenesis was performed with a suitable concentration of diethyl sulfate. Subsequently, a high-yielding and genetically stable strain (H6-32) was obtained by screening, with a sisomicin titer of 1486 U·mL-1 (an increase of 42.6%). Finally, carbon and nitrogen sources were optimized to further improve sisomicin production, and a sisomicin titer of 1780 U·mL-1 was ultimately obtained by controlling the dissolved oxygen level at 30% in a 5-L fermenter, which to the best of our knowledge is the highest reported titer ever achieved by fermentation. Comparative genome analysis showed that a total of 13 genes in the genome of the mutant strain H6-32 were mutated compared to the original strain. This study not only provides a reference for further breeding of high-yielding strains and fermentation optimization, but also enhances our understanding of sisomicin production.

Efficient production and characterization of a newly identified trehalase for inhibiting the formation of bacterial biofilms.

Trehalase has attracted widespread attention in medicine, agriculture, food, and ethanol industry due to its ability to specifically degrade trehalose. Efficient expression of trehalase remains a challenge. In this study, a putative trehalase-encoding gene (Tre-zm) from Zunongwangia mangrovi was explored using gene-mining strategy and heterologously expressed in E. coli. Trehalase activity reached 3374 U·mL-1 after fermentation optimization. The scale-up fermentation in a 15 L fermenter was achieved with a trehalase production of 15,068 U·mL-1. The recombinant trehalase TreZM was purified and characterized. It displayed optimal activity at 35 °C and pH 8.5, with Mn2+, Sn2+, Na+, and Fe2+ promoting the activity. Notably, TreZM showed significant inhibition effect on biofilm forming of Staphylococcus epidermidis. The combination of TreZM with a low concentration of antibiotics could inhibit 70 % biofilm formation of Staphylococcus epidermidis and 28 % of Pseudomonas aeruginosa. Hence, this study provides a promising candidate for industrial production of trehalase and highlights its potential application to control harmful biofilms.

Engineering protein translocation and unfolded protein response enhanced human PH-20 secretion in Pichia pastoris.

Hyaluronidases catalyze the degradation of hyaluronan (HA), which is finding rising applications in medicine, cosmetic, and food industries. Recombinant expression of hyaluronidases in microbial hosts has been given special attention as a sustainable way to substitute animal tissue-derived hyaluronidases. In this study, we focused on optimizing the secretion of hyaluronidase from Homo sapiens in Pichia pastoris by secretion pathway engineering. The recombinant hyaluronidase was first expressed under the control of a constitutive promoter PGCW14. Then, two endoplasmic reticulum-related secretory pathways were engineered to improve the secretion capability of the recombinant strain. Signal peptide optimization suggested redirecting the protein into co-translational translocation using the ost1-proα signal sequence improved the secretion level by 20%. Enhancing the co-translational translocation by overexpressing signal recognition particle components further enhanced the secretory capability by 48%. Then, activating the unfolded protein response by overexpressing a transcriptional factor ScHac1p led to a secreted hyaluronidase activity of 4.06 U/mL, which was 2.1-fold higher than the original strain. Finally, fed-batch fermentation elevated the production to 19.82 U/mL. The combined engineering strategy described here could be applied to enhance the secretion capability of other proteins in yeast hosts. KEY POINTS: • Improving protein secretion by enhancing co-translational translocation in P. pastoris was reported for the first time. • Overexpressing Hac1p homologous from different origins improved the rhPH-20 secretion. • A 4.9-fold increase in rhPH-20 secretion was achieved after fermentation optimization and fed-batch fermentation.

Lactic acid fermentation of goji berries (Lycium barbarum) prevents acute alcohol liver injury and modulates gut microbiota and metabolites in mice.

Juice fermented with lactic acid bacteria (LAB) has received attention due to its health benefits, such as antioxidant and anti-inflammatory. Previous research on LAB-fermented goji juice mainly focused on exploring the changes in the metabolite profile and antioxidant activity in vitro, whereas the liver protection properties of LAB-fermented goji juice in vivo are still unknown. This study aimed to investigate the effects of Lacticaseibacillus paracasei E10-fermented goji juice (E10F), Lactiplantibacillus plantarum M-fermented goji juice (MF), Lacticaseibacillus rhamnosus LGG-fermented goji juice (LGGF) on preventing acute alcoholic liver injury with physiology, gut microbial, and metabolic profiles in mice. Compared with goji juice, E10F, MF, and LGGF enhanced the protective effect against liver injury by reducing serum alanine transaminase (ALT) levels, improving the hepatic glutathione (GSH) antioxidant system, and attenuating inflammation by decreasing the levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-ß. Furthermore, E10F, MF, and LGGF increased intestinal integrity, restructured the gut microbiota including Bacteroides and Lactobacillus, and altered gut microbial metabolites including kyotorphin, indolelactic acid, and N-methylserotonin. Pretreatment of different LAB-fermented goji juice in mice showed significant differences in gut microbiota and metabolism. The correlation analysis demonstrated that the increase of Lactobacillus, indolelactic acid, and N-methylserotonin by E10F, MF, and LGGF was positively correlated with reduced inflammation and improved liver and gut function. Taken together, E10F, MF, and LGGF all have the potential to be converted into dietary interventions to combat acute alcoholic liver injury. It provided a reference for the study of the hepatoprotective effect of LAB-fermented goji juice.

Production of L-serine and its derivative L-cysteine from renewable feedstocks using Corynebacterium glutamicum: advances and perspectives.

L-serine and its derivative L-cysteine have broad industrial applications, and their direct fermentative production from renewable biomass is gaining increasing attention. Corynebacterium glutamicum is an extensively studied and well-established industrial microorganism, which is a predominant microbial host for producing amino acids. In this review, updated information on the genetics and molecular mechanisms underlying L-serine and L-cysteine production using C. glutamicum is presented, including their synthesis and degradation pathways, and other intracellular processes related to their production, as well as the mechanisms underlying substrate import and product export are also analyzed. Furthermore, metabolic strategies for strain improvement are systematically discussed, and conclusions and future perspectives for bio-based L-serine and L-cysteine production using C. glutamicum are presented. This review can provide a thorough understanding of L-serine and L-cysteine metabolic pathways to facilitate metabolic engineering modifications of C. glutamicum and development of more efficient industrial fermentation processes for L-serine and L-cysteine production.

Enhanced L-serine production by Corynebacterium glutamicum based on novel insights into L-serine exporters.

The L-serine exporters ThrE and SerE play important roles in L-serine production by Corynebacterium glutamicum. Deletion of both thrE and serE decreased L-serine titer by 60%, suggesting the existence of other L-serine exporters. A comparative transcriptomics identified NCgl0254 and NCgl0255 as novel L-serine exporters. Further analysis of the contributions of ThrE, SerE, NCgl0254, and NCgl0255 found that SerE was the major L-serine exporter in C. glutamicum and these four L-serine exporters were responsible for 79.7% of L-serine export. Deletion of one L-serine exporter upregulated the transcription levels of the other three, which might be coursed by increased intracellular concentrations of L-serine. Overexpression of NCgl0254 and NCgl0255 increased L-serine titer by 20.8% in C. glutamicum A36, while overexpression of the four L-serine exporters increased L-serine production by 31.9% (41.1 g·L-1 ) in C. glutamicum A36. The identification of novel L-serine exporters in C. glutamicum will help to improve industrial production of L-serine.

Enhanced poly-γ-glutamic acid synthesis in Corynebacterium glutamicum by reconstituting PgsBCA complex and fermentation optimization.

Previously, a novel Corynebacterium glutamicum strain for the de novo biosynthesis of tailored poly-γ-glutamic acid (γ-PGA) has been constructed by our group. The strain was based on the γ-PGA synthetase complex, PgsBCA, which is the only polyprotein complex responsible for γ-PGA synthesis in Bacillus spp. In the present study, PgsBCA was reconstituted and overexpressed in C. glutamicum to further enhance γ-PGA synthesis. First, we confirmed that all the components (PgsB, PgsC, and PgsA) of γ-PGA synthetase derived from B. licheniformis are necessary for γ-PGA synthesis, and γ-PGA was detected only when PgsB, PgsC, and PgsA were expressed in combination in C. glutamicum. Next, the expression level of each pgsB, pgsC, and pgsA was tuned in order to explore the effect of expression of each of the γ-PGA synthetase subunits on γ-PGA production. Results showed that increasing the transcription levels of pgsB or pgsC and maintaining a medium-level transcription level of pgsA led to 35.44% and 76.53% increase in γ-PGA yield (γ-PGA yield-to-biomass), respectively. Notably, the expression level of pgsC had the greatest influence (accounting for 68.24%) on γ-PGA synthesis, followed by pgsB. Next, genes encoding for PgsC from four different sources (Bacillus subtilis, Bacillus anthracis, Bacillus methylotrophicus, and Bacillus amyloliquefaciens) were tested in order to identify the influence of PgsC-encoding orthologues on γ-PGA production, but results showed that in all cases the synthesis of γ-PGA was significantly inhibited. Similarly, we also explored the influence of gene orthologues encoding for PgsB on γ-PGA production, and found that the titer increased to 17.14 ± 0.62 g/L from 8.24 ± 0.10 g/L when PgsB derived from B. methylotrophicus replaced PgsB alone in PgsBCA from B. licheniformis. The resulting strain was chosen for further optimization, and we achieved a γ-PGA titer of 38.26 g/L in a 5 L fermentor by optimizing dissolved oxygen level. Subsequently, by supplementing glucose, γ-PGA titer increased to 50.2 g/L at 48 h. To the best of our knowledge, this study achieved the highest titer for de novo production of γ-PGA from glucose, without addition of L-glutamic acid, resulting in a novel strategy for enhancing γ-PGA production.

Engineering of redox partners and cofactor NADPH supply of CYP68JX for efficient steroid two-step ordered selective hydroxylation activity.

CYP68JX, a P450 hydroxylase, derived from Colletotrichum lini ST-1 is capable of biotransforming dehydroepiandrosterone (DHEA) to 3ß,7α,15α-trihydroxy-5-androstene-17-one (7α,15α-diOH-DHEA). Redox partners and cofactor supply are important factors affecting the catalytic activity of CYP68JX. In this study, the heterologous expression of CYP68JX in Saccharomyces cerevisiae BY4741 was realized resulting in a 17.1% target product yield. In order to increase the catalytic efficiency of CYP68JX in S. cerevisiae BY4741, a complete cytochrome P450 redox system was constructed. Through the combination of CYP68JX and heterologous CPRs, the yield of the target product 7α,15α-diOH-DHEA in CYP68JX recombinant system was increased to 37.8%. Furthermore, by adding NADPH coenzyme precursor tryptophan of 40 mmol/L and co-substrate fructose of 20 g/L during the conversion process, the catalytic efficiency of CYP68JX was further improved, the target product yield reached 57.9% which was 3.39-fold higher than initial yield. Overall, this study provides a reference for improving the catalytic activity of P450s.

Molecular dynamics-based study of the modification mechanism of asphalt by graphene oxide.

CONTEXT: Graphene oxide(GO) has been widely used in asphalt modification due to its excellent properties. To reveal the interaction effect between GO and asphalt materials, the microscopic behavior and molecular structure changes of asphalt and GO/asphalt were investigated by molecular dynamics (MD) simulations. Mean square displacement (MSD) results showed that GO significantly inhibited the diffusion of molecules of asphalt components. Radial distribution function (RDF) results that GO destroys the original sol-type structure of asphalt. Simultaneously, GO adsorbed resins at low-temperature, adsorbed asphaltenes at high-temperature, and dispersed as a dispersed phase in the light components. The concentration of the dispersed phase in the asphalt colloidal structure was increased and the mutual attraction was enhanced. This improves the deformation resistance at high temperature, but weakens the ductility at low temperatures. METHODS: To investigate the mechanism of action of GO-modified asphalt, the asphalt model and the GO/asphalt composite system model were constructed using the Amorphous Cell module in Materials Studio 2020 software. Subsequently, molecular dynamics simulations of the GO/asphalt composite system were performed using the Forcite module, while the interactions between atoms and molecules were described using the COMPASS II force field.

Solibacillus daqui sp. nov., isolated from high-temperature Daqu.

A Gram-stain-positive, rod-shaped, endospore-forming, aerobic bacterial strain, designated ZS111008T, was isolated from high-temperature Daqu, a starter for production of Chinese Jiang-flavour Baijiu, and was characterized by polyphasic taxonomy. This novel isolate grew in the presence of 0-5 % (w/v) NaCl, at pH 6.0-9.0 and 25-45 °C; optimum growth was observed with 1 % (w/v) NaCl, at pH 8.0 and 30 °C. A comparative analysis of the 16S rRNA gene sequence (1461 bp) of strain ZS111008T showed highest similarity to Solibacillus silvestris DSM12223T (96.7%), followed by Solibacillus cecembensis PN5T (96.6%) and Solibacillus isronensis AMCK01000046 (96.5%). The DNA G+C content of strain ZS111008T was 37.21 mol%. The respiratory quinone was identified as menaquinone-7 and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine and one unknown phospholipid. Lys was detected as the diagnostic diamino acid in the cell wall. Based on morphological characteristics, chemotaxonomic characteristics and physiological properties, strain ZS111008T represents a novel species of the genus Solibacillus, for which the name Solibacillus daqui sp. nov. is proposed. The type strain for this proposed species is ZS111008T (=CGMCC 1.19455T=JCM 35214T).

Microbial biogeography of pit mud from an artificial brewing ecosystem on a large time scale: all roads lead to Rome.

IMPORTANCE: Baijiu is a typical example of how humans employ microorganisms to convert grains into new flavors. Mud cellars are used as the fermentation vessel for strong-flavor Baijiu (SFB) to complete the decomposition process of grains. The typical flavor of SFB is mainly attributed to the metabolites of the pit mud microbiome. China has a large number of SFB-producing regions. Previous research revealed the temporal profiles of the pit mud microbiome in different geographical regions. However, each single independent study rarely yields a thorough understanding of the pit mud ecosystem. Will the pit mud microbial communities in different production regions exhibit similar succession patterns and structures under the impact of the brewing environment? Hence, we conducted research in pit mud microbial biogeography to uncover the impact of specific environment on the microbial community over a long time scale.

Aggravated hepatic fibrosis induced by phenylalanine and tyrosine was ameliorated by chitooligosaccharides supplementation.

Hepatic fibrosis is a classic pathological manifestation of metabolic chronic hepatopathy. The pathological process might either gradually deteriorate into cirrhosis and ultimately liver cancer with inappropriate nutrition supply, or be slowed down by several multifunctional nutrients, alternatively. Herein, we found diet with excessive phenylalanine (Phe) and tyrosine (Tyr) exacerbated hepatic fibrosis symptoms of liver dysfunction and gut microflora dysbiosis in mice. Chitooligosaccharides (COS) could ameliorate hepatic fibrosis with the regulation of amino acid metabolism by downregulating the mTORC1 pathway, especially that of Phe and Tyr, and also with the alleviation of the dysbiosis of gut microbiota, simultaneously. Conclusively, this work presents new insight into the role of Phe and Tyr in the pathologic process of hepatic fibrosis, while revealing the effectiveness and molecular mechanism of COS in improving hepatic fibrosis from the perspective of metabolites.

Lentibacillus daqui sp. nov., isolated from high-temperature Daqu, a starter for production of Chinese Jiang-flavour Baijiu.

A Gram-stain-positive, rod-shaped, endospore-forming, aerobic bacterial strain, designated ZS110521T, was isolated from high-temperature Daqu, a starter for production of Chinese Jiang-flavour Baijiu and was characterised by polyphasic taxonomy. This novel isolate grew in the presence of 0-20 % (w/v) NaCl, at pH 6.0-9.0 and 20-50 °C; optimum growth was observed with 8-10 % (w/v) NaCl, at pH 7.0 and 37 °C. A comparative analysis of the 16S rRNA gene sequence (1460 bp) of ZS110521T revealed that it displayed the highest similarity to Lentibacillus populi WD4L-1T (95.5 %), followed by Lentibacillus garicola SL-MJ1T (95.4 %) and Lentibacillus lacisalsi BH260T (95.2 %). ANI and dDDH values between ZS110521T and other strains of species of the genus Lentibacillus were less than 78 and 28 %, respectively. The predominant cellular fatty acids (> 10 %) of ZS110521T were anteiso-C17 : 0 (37.8 %), anteiso-C15 : 0 (28.1 %) and iso-C16 : 0 (15.5 %). The respiratory quinone was identified as menaquinone-7 (MK-7) and the major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The polyphasic taxonomic data and the results of chemotaxonomic analysis confirmed that ZS110521T represents a novel species, for which the name Lentibacillus daqui sp. nov. is proposed. The type strain of this proposed species is ZS110521T (=CGMCC 1.19456T =JCM 35213T).

Technology and functional insights into the nicotinamide mononucleotide for human health.

Nicotinamide mononucleotide (NMN), a naturally occurring biologically active nucleotide, mainly functions via mediating the biosynthesis of NAD+. In recent years, its excellent pharmacological activities including anti-aging, treating neurodegenerative diseases, and protecting the heart have attracted increasing attention from scholars and entrepreneurs for production of a wide range of formulations, including functional food ingredients, health care products, active pharmaceuticals, and pharmaceutical intermediates. Presently, the synthesis methods of NMN mainly include two categories: chemical synthesis and biosynthesis. With the development of biocatalyst engineering and synthetic biology strategies, bio-preparation has proven to be efficient, economical, and sustainable methods. This review summarizes the chemical synthesis and biosynthetic pathways of NMN and provides an in-depth investigation on the mining and modification of enzyme resources during NMN biosynthesis, as well as the screening of hosts and optimization of chassis cells via metabolic engineering, which provide effective strategies for efficient production of NMN. In addition, an overview of the significant physiological functions and activities of NMN is elaborated. Finally, future research on technical approaches to further enhance NMN synthesis and strengthen clinical studies of NMN are prospected, which would lay the foundation for further promoting the application of NMN in nutrition, healthy food, and medicine in the future. KEY POINTS: • NMN supplementation effectively increases the level of NAD+. • The chemical and biological synthesis of NMN are comprehensively reviewed. • The impact of NMN on the treatment of various diseases is summarized.