Liamocins overproduction via the two-pH stage fermentation and anti-Aspergillus flavus activity of Massoia lactone.

Aureobasidium melanogenum was found to be grown the best at the constant pH 7.0 and to produce the highest amount of liamocins at the constant pH 3.0. Therefore, the wild type strain A. melanogenum 9-1 and the engineered strain V33 constructed in the laboratory were grown at the constant pH 7.0 for 48 h, then, they were continued to be cultivated at the constant pH 3.0. Under such conditions, A. melanogenum 9-1 produced 36.51 ± 0.55 g L-1 of liamocin and its cell mass was 27.43 ± 0.63 and 6.00 ± 0.11 g L-1 of glucose was left in the finished medium within 168 h while the engineered strain V33 secreted 70.86 ± 2.04 g L-1 of liamocin, its cell mass was 31.63 ± 0.74 g L-1 , 0.16 ± 0.01 g L-1 of glucose was maintained in the finished medium. Then, Massoia lactone was released from the produced liamocins. The released Massoia lactone loaded in the nanoemulsions could be used to actively damage cell wall and cell membrane of both spores and mycelia of Aspergillus flavus, leading to its cell necrosis. Massoia lactone loaded in the nanoemulsions also actively inhibited cell growth of A. flavus, its conidia production and aflatoxin biosynthesis on peanuts, indicating that Massoia lactone loaded in the nanoemulsions had highly potential application in controlling cell growth of A. flavus and aflatoxin biosynthesis in foods and feedstuffs.

Gastric Mucosa-Associated Microbial Signatures of Early Gastric Cancer.

Alterations in the microbiome are associated with the development of gastric cancer. Our study aimed to identify dysbiotic features in early gastric cancer (EC). The gastric microbiome was assessed in EC (n = 30), advanced gastric cancer (AC) (n = 30), and chronic gastritis (CG) (n = 60). The results demonstrated significant differences in the microbial profile and composition between EC and AC, suggesting alterations associated with gastric cancer progression. Linear discriminant analysis (LDA) effect size (LEfSe) analyses identified 32 bacterial genera that were associated with EC. Functional analyses of the gastric microbiome showed that the production of urease and synthesis of bacterial flagella were weakened in EC, while the glycolysis of fructose and hydrolysis of glycosides were enhanced. A classifier based on a random forest (RF) machine learning algorithm identified a microbial signature that distinguished EC from CG or AC with high accuracy. The correct identification of the signature was further validated in independent cohorts. This signature enriched of bacteria with varied abundance, high degree of bacterial interactions and carcinogenic potentials. Constrained principal coordinate analyses revealed that the presence of Helicobacter pylori and the cagA and vacA virulence genotypes influenced the structure of the gastric microbiome. To determine the impacts of host genetic variations on the gastric microbiome, six previously reported single nucleotide polymorphisms (SNPs) were examined. The minor allele of MUC1 rs4072037 was associated with an increased abundance of Ochrobactrum. The gastric microbiome altered in EC, which might be attributed in part to host genetic variations, H. pylori infection, bacterial virulence and environmental adaptations. The identified microbial signature could serve as biomarkers for clinical assessment of gastric cancer risk in high-risk patients.

Biglycan as a potential diagnostic and prognostic biomarker in multiple human cancers.

Biglycan (BGN), a key member of the small leucine-rich proteoglycan family, is an important component of the extracellular matrix. Clinical studies have demonstrated that upregulation of BGN is associated with poor prognosis in patients with various types of solid cancer. The present study analyzed the mRNA expression levels of BGN in various types of solid cancer when compared with that in normal tissues via the Oncomine database. The UALCAN, OncoLnc and Kaplan-Meier Plotter databases were additionally used to evaluate the prognostic values of BGN in patients with solid cancer and co-expression gene analysis was conducted using the protein-protein interaction networks of BGN. The present study observed that the mRNA expression levels of BGN were increased in bladder, brain and central nervous system, breast, colorectal, esophageal, gastric, head and neck, lung, ovarian and 28 subtypes of cancer compared with normal tissues. The increased expression of BGN was identified to be associated with a poor outcome in ovarian and gastric cancer. Based on the co-expression network, BGN was identified as the key gene in a 43-gene network. The present findings of increased expression of BGN in solid tumors and its positive association with poor outcome on patient survival indicate that BGN may serve as a prognostic marker and as a target for novel therapeutics for multiple types of cancer.

AKR1C1-3, notably AKR1C3, are distinct biomarkers for liver cancer diagnosis and prognosis: Database mining in malignancies.

Aldo-keto reductases, known as AKR1C1-AKR1C4 enzymes, are pivotal to NADPH-dependent reduction, and their expression is highly associated with the progression of malignant cancers. However, the expression and distinct prognostic value of the AKR1C family members in liver cancer are not well established. In the current study, the expression of AKR1C isoforms was studied using the Oncomine online databases. In addition, their expression profiles were analyzed in cancer cell lines using data from the Cancer Cell lines Encyclopedia (CCLE) database. Furthermore, the mRNA expression levels of AKR1C family members between liver cancer and normal liver samples were assessed by the Gene Expression Profiling Interactive Analysis (GEPIA) database. The AKR1C1-3 prognostic value was further investigated by the Kaplan-Meier plotter database in liver cancer patients. It was found that the expression levels of AKR1C3 were elevated significantly in liver cancer tissues and cells as demonstrated by the Oncomine, CCLE and GEPIA databases. The expression levels of AKR1C1 and AKR1C2 in liver cancer tissues did not increase significantly in the Oncomine database while expression was significantly high in CCLE and GEPIA databases. However, the expression levels of the AKR1C4 gene as determined by the CCLE, GEPIA and Oncomine databases were not consistent. Therefore, the Kaplan-Meier survival curves of liver cancer patients with the expression of AKR1C1-3 genes were next analyzed. The data indicated that high expression levels of AKR1C1-3 were correlated with lower overall survival in liver cancer patients. Using the co-expression and PPI network, AKR1C1-3 genes were identified that were involved in the same pathway displaying 44 total unique interactors. These results suggested that the increased AKR1C1-3, notably AKR1C3 expression levels served as possible diagnostic biomarkers and essential prognostic factors for liver cancer patients. The roles of AKR1C4 in liver cancer require further examination.

Biosynthesis of some organic acids and lipids in industrially important microorganisms is promoted by pyruvate carboxylases.

Pyruvate carboxylase (Pyc) catalyzes formation of oxaloacetic acid from pyruvic acid by fixing one mole of CO2. Many evidences have confirmed that biosynthesis of some different kinds of organic acids and intracellular and extracellular lipids is driven by Pyc and over-expression of the PYC gene in the industrial microorganisms can promote production of the different kinds of organic acids and intracellular and extracellular lipids. Therefore, the Pyc from different sources is regarded as a key enzyme in microbial biotechnology and is an important target for metabolic engineering of the industrial microbial strains. However, very little is known about the native Pycs and their functions and regulation in the industrial microorganisms.

Association between gallstone and cardio-cerebrovascular disease: Systematic review and meta-analysis.

Increasing evidence connects gallstone disease (GD) to cardio-cerebrovascular disease (CVD). The aim of the present systematic review and meta-analysis was to determine whether and to what extent an association between GD and CVD existed. PubMed, EMBASE and the Cochrane Library were systemically searched up to March 3rd, 2018. A total of 10 studies (1,272,177 participants; 13,833 records; 5 prospective cohorts and 5 retrospective cohorts) were included. It was demonstrated that GD was associated with an increased risk of incidence [hazard ratio=1.24, 95% (CI) confidence interval: 1.17-1.31] and prevalence (unadjusted odds ratio=1.23, 95% CI: 1.21-1.25) of CVD. In conclusion, the presence of GD was associated with an increased risk of CVD incidence and prevalence. The association may be influenced by age and sex. These findings suggest that individuals identified with cardio-cerebrovascular disease should be evaluated for GD.

Combined enzymatic hydrolysis and selective fermentation for green production of alginate oligosaccharides from Laminaria japonica.

Alginate oligosaccharides (AOS) showed various biological activities. Traditional protocol for producing AOS was a multiple-step and high-pollution procedure. In this study, a rapid and efficient AOS producing method was developed directly from Laminaria japonica. Natural sun-dried L. japonica with a feed ratio of 1:7 (w/v) was pretreated using cellulase with a dry weight of 3%, for releasing the fermentable sugars (8.5 g/L glucose and 15.2 g/L mannitol). Then, the engineered yeast Yarrowia lipolytica strain with alginate lyase activity was grown using an algae-based medium. After fermentation for 72 h, glucose and mannitol were completely consumed, and 71.8 mM AOS was extracted from the fermentation supernatant. The degree of polymerization (DP) was ranging from 2 to 3. The recovery yield of AOS was about 91.7%. The purity of the extracted AOS was 92.6%. Overall, our work provided new insights for the development of green biotechnologies for oligosaccharide production from seaweed.

Genome sequencing of Aureobasidium pullulans P25 and overexpression of a glucose oxidase gene for hyper-production of Ca2+-gluconic acid.

Gluconic acid (GA) has many applications such as in the food and pharmaceutical industry. Aureobasidium pullulans P25 strain is able to produce high levels of Ca2+-GA. The genome length, GC content and the gene number of this yeast were found to be 30.97 Mb, 50.28% and 10,922, respectively. The pathways for gluconic acid biosynthesis were annotated. Glucose oxidase (Gox) sequences from different strains of A. pullulans were highly similar but were distinct from those of other fungi. The glucose oxidase had two FAD binding sites and a signal sequence. Deletion of the GOX gene resulted in a strain that showed no Gox activity and that was unable to produce Ca2+-GA. Overexpression of the GOX gene in strain P25 generated strain GA-6 that produced 200.2 ± 2.3 Ca2+-GA g/l and 2480 U/mg of Gox activity. The productivity of Ca2+-GA was 2.78 g/l/h and the yield was 1.1 g/g.

Cloning and Characterization of a Pyruvate Carboxylase Gene from Penicillium rubens and Overexpression of the Genein the Yeast Yarrowia lipolytica for Enhanced Citric Acid Production.

In this study, a pyruvate carboxylase gene (PYC1) from a marine fungus Penicillium rubens I607 was cloned and characterized. ORF of the gene (accession number: KM397349.1) had 3534 bp encoding 1177 amino acids with a molecular weight of 127.531 kDa and a PI of 6.20. The promoter of the gene was located at -1200 bp and contained a TATAA box, several CAAT boxes and a sequence 5'-SYGGRG-3'. The PYC1 deduced from the gene had no signal peptide, was a homotetramer (α4), and had the four functional domains. After expression of the PYC1 gene from the marine fungus in the marine-derived yeast Yarrowia lipolytica SWJ-1b, the transformant PR32 obtained had much higher specific pyruvate carboxylase activity (0.53 U/mg) than Y. lipolytica SWJ-1b (0.07 U/mg), and the PYC1 gene expression (133.8%) and citric acid production (70.2 g/l) by the transformant PR32 were also greatly enhanced compared to those (100 % and 27.3 g/l) by Y. lipolytica SWJ-1b. When glucose concentration in the medium was 60.0 g/l, citric acid (CA) concentration formed by the transformant PR32 was 36.1 g/l, leading to conversion of 62.1% of glucose into CA. During a 10-l fed-batch fermentation, the final concentration of CA was 111.1 ± 1.3 g/l, the yield was 0.93 g/g, the productivity was 0.46 g/l/h, and only 1.72 g/l reducing sugar was left in the fermented medium within 240 h. HPLC analysis showed that most of the fermentation products were CA. However, minor malic acid and other unknown products also existed in the culture.

Disruption of the acid protease gene in Saccharomycopsis fibuligera A11 enhances amylolytic activity and stability as well as trehalose accumulation.

The acid protease gene in Saccharomycopsis fibuligera A11 was disrupted by integrating the HPT (hygromycin B phosphotransferase) gene into ORF (Open Reading Frame) of the acid protease gene. The mutant 12 obtained could grow in the medium containing hygromycin. No clear zone formed by the mutant grown on the plate containing milk protein was observed whereas a big clear zone formed by the strain A11 was detected. The acid protease and amylases activities produced by the mutant within 3 days were 0.89 U/ml and 424.7 U/ml, respectively while those produced by the strain A11 were 13.5 U/ml and 259.9 U/ml, respectively. The amylases preparations produced by the mutant 12 and the strain A11 kept 88.8% and 45.5% of amylase activity, respectively after they were incubated at 37°C for two days. Trehalose amount accumulated in the mutant cells was 28.3% (w/w) while that accumulated in the cells of S. fibuligera A11 was 23.6 (w/w).

Mig1 is involved in mycelial formation and expression of the genes encoding extracellular enzymes in Saccharomycopsis fibuligera A11.

The MIG1 gene of Saccharomycopsis fibuligera A11 was cloned from its genomic DNA using the degenerated primers and inverse PCR. The MIG1 gene (1152bp, accession number: HM450676) encoded a 384-amino acid protein very similar to Mig1s from other fungi. Besides their highly conserved zinc fingers, the Mig1 proteins displayed short conserved motifs of possible significance in glucose repression. The MIG1 gene in S. fibuligera A11 was disrupted by integrating the HPT (hygromycin B phosphotransferase) gene into ORF (Open Reading Frame) of the MIG1 gene. The disruptant A11-c obtained could grow in the media containing hygromycin and 2-deoxy-d-glucose, respectively. α-Amylase, glucoamylse, acid protease and ß-glucosidase production by the disruptant and expression of their genes in the disruptant were greatly enhanced. This confirms that Mig1, the transcriptional repressor, indeed regulates expression of the genes and production of the extracellular enzymes in S. fibuligera A11. At the same time, it was found that cell budding was enhanced and mycelial formation was reduced in the disruptant.

Trehalose accumulation from cassava starch and release by a highly thermosensitive and permeable mutant of Saccharomycopsis fibuligera.

Highly thermosensitive and permeable mutants are the mutants from which intracellular contents can be released when they are incubated both in low osmolarity water and at non-permissive temperature (usually 37°C). After mutagenesis by using nitrosoguanidine, a highly thermosensitive and permeable mutant named A11-b was obtained from Saccharomycopsis fibuligera A11-12, a trehalose overproducer in which the acid protease gene has been disrupted. Of the total trehalose, 73.8% was released from the mutant cells suspended in distilled water after they had been treated at 37°C overnight. However, only 10.0% of the total trehalose was released from the cells of S. fibuligera A11-12 treated under the same conditions. The cell volume of the mutant cells suspended in distilled water and treated at 37°C overnight was much bigger than that of S. fibuligera A11-12 treated under the same conditions. The cell growth and trehalose accumulation of the mutant were almost the same as those of S. fibuligera A11-12 during the cultivation at the flask level and in a 5-l fermentor. Both could accumulate around 28.0% (w/w) trehalose from cassava starch. After purification, the trehalose crystal from the aqueous extract of the mutant was obtained.

Marine yeasts as biocontrol agents and producers of bio-products.

As some species of marine yeasts can colonize intestine of marine animals, they can be used as probiotics. It has been reported that beta-glucans from marine yeast cells can be utilized as immuno-stimulants in marine animals. Some siderophores or killer toxins produced by marine yeasts have ability to inhibit growth of pathogenic bacteria or kill pathogenic yeasts in marine animals. The virulent factors from marine pathogens can be genetically displayed on marine yeast cells, and the yeast cells displaying the virulent factors can stimulate marine animals to produce specific antibody against the pathogens. Some marine yeast cells are rich in proteins and essential amino acids and can be used in nutrition for marine animals. The marine yeast cells rich in lipid can be used for biodiesel production. Recently, it has been reported that some strains of Yarrowia lipolytica isolated from marine environments can produce nanoparticles. Because many marine yeasts can remove organic pollutants and heavy metals, they can be applied to remediation of marine environments. It has been shown that the enzymes produced by some marine yeasts have many unique properties and many potential applications.

[Eukaryotic expression of Leptospira interrogans lipL32/1-ompL1/1 fusion gene encoding genus-specific protein antigens and the immunoreactivity of expression products].

OBJECTIVE: To construct the eukaryotic expression system of L.interrogans lipL32/1-ompL1/1 fusion gene and to identify the immunoreactivity of expression products. METHODS: PCR with linking primer was used to construct the fusion gene lipL32/1-ompL1/1. The P.pastoris eukaryotic expression system of the fusion gene, pPIC9K-lipL32/1-ompL1/1-P. pastorisGS115, was constructed after the fusion gene was cloned and sequenced. Colony with phenotype His(+)Mut(+) was isolated by using MD and MM plates and His(+) Mut(+) transformant with high resistance to G418 was screened out by using YPD plate. Using lysate of His(+) Mut(+) colony with high copies of the target gene digested with yeast lyase as the template and 5'AOX1 and 3'AOX1 as the primers, the target fusion gene in chromosome DNA of the constructed P. pastoris engineering strain was detected by PCR. Methanol in BMMY medium was used to induce the target recombinant protein rLipL32/1-rOmpL1/1 expression. rLipL32/1-rOmpL1/1 in the medium supernatant was extracted by using ammonium sulfate precipitation and Ni-NTA affinity chromatography. Output and immunoreactivity of rLipL32/1-rOmpL1/1 were measured by SDS-PAGE and Western blot methods, respectively. RESULTS: Amplification fragments of the obtained fusion gene lipL32/1-ompL1/1 was 1794 bp in size. The homogeneity of nucleotide and putative amino acid sequences of the fusion gene were as high as 99.94 % and 100 %, respectively, compared with the sequences of original lipL32/1 and ompL1/1 genotypes. The constructed eukaryotic expression system was able to secrete rLipL32/1-rOmpL1/1 with an output of 10 % of the total proteins in the supernatant, which located the expected position after SDS-PAGE. The rabbit anti-rLipL32/1 and anti-rOmpL1/1 sera could combine the expressed rLipL32/1-rOmpL1/1. CONCLUSION: An eukaryotic expression system with high efficiency in P.pastoris of L.interrogans lipL32/1-ompL1/1 fusion gene was successfully constructed in this study. The expressed fusion protein shows specific immunoreactivity, which can be used as a potential antigen for developing a novel vaccine of L.interrogans.

[Effects of lactose inducing on expression of Helicobacter pylori rUreB and rHpaA, and Escherichia coli rLTKA63 and rLTB].

OBJECTIVE: To determine the effects of lactose inducing on the expression of recombinant Helicobacter pylori rUreB and rhpaA, and Escherichia coli rLTB and rLTKA63. METHODS: BIO-RAD gel image analysis system was applied to detect the outputs of the recombinant proteins. SDS-PAGE was performed to measure the target protein expression of recombinant genes at various periods of growth, different lactose concentrations, various inducing temperatures and times. The results of the target protein expression induced by lactose were compared to those by isopropyl-beta-D-thiogalactoside (IPTG). RESULTS: Lactose showed higher efficiency to induce the expression of rHpaA, rUreB, rLTB and rLTKA63 than IPTG. The expression outputs of target recombinant proteins induced at 37 degrees C were remarkably higher than those at 28 degrees C. The optimal expression parameters were 0.8 of OD600 value, 50 g/L of lactose, 4 hours of inducing time for rHpaA, and 1.2 of OD600 value, 100 g/L of lactose, 5 hours of inducing time for both the rUreB and rLtB,and 0.8 of OD600 value, 100 g/L of lactose, 4 hours for rLTKA63. CONCLUSION: Lactose, a sugar with non-toxicity and low cost, is able to induce the recombinant genes to express the target proteins with higher efficiency than IPTG.

Effects of lactose as an inducer on expression of Helicobacter pylori rUreB and rHpaA, and Escherichia coli rLTKA63 and rLTB.

AIM: To demonstrate the effect of lactose as an inducer on expression of the recombinant proteins encoded by Helicobacter pylori ureB and hpaA, and Escherichia coli LTB and LTKA63 genes and to determine the optimal expression parameters. METHODS: By using SDS-PAGE and BIO-RAD gel image analysis system, the outputs of the target recombinant proteins expressed by pET32a-ureB-E.coliBL21, pET32a-hpaA-E.coliBL21, pET32a-LTKA63-E.coliBL21 and pET32a-LTB-E.coliBL21 were measured when using lactose as inducer at different dosages, original bacterial concentrations, various inducing temperatures and times. The results of the target protein expression induced by lactose were compared to those by isopropyl-beta-D-thiogalactoside (IPTG). The proteins were expressed in E.coli. RESULTS: Lactose showed higher efficiency of inducing the expression of rHpaA, rUreB, rLTB and rLTKA63 than IPTG. The expression outputs of the target recombinant proteins induced at 37 degrees were remarkably higher than those at 28 degrees. Other optimal expression parameters for the original bacterial concentrations, dosages of lactose and inducing time were 0.8, 50 g/L and 4 h for rHpaA; 0.8, 100 g/L and 4 h for rLTKA63; 1.2, 100 g/L and 5 h for both rUreB and rLTB, respectively. CONCLUSION: Lactose, a sugar with non-toxicity and low cost, is able to induce the recombinant genes to express the target proteins with higher efficiency than IPTG. The results in this study establish a beneficial foundation for industrial production of H pylori genetic engineering vaccine.

[Cloning, expression and identification of Escherichia coli LTB gene and Vibrio cholerae CTB gene].

OBJECTIVE: To clone the LTB gene of E.coli and the CTB gene of V.cholerae, and to construct expression vectors of these genes. METHODS: The LTB gene from E.coli strain 44815 and the CTB gene from V.cholerae strain eastern 74 were amplified by high fidelity PCR. The nucleotide sequences of the two target DNA amplification fragments were sequenced after T-A cloning. pET32a expression vectors with inserted LTB and CTB genes were constructed. The LTB and CTB fusion proteins were expressed in E.coli strain BL21DE3 inducted by IPTG at different dosages. The two expression products were identified by SDS-PAGE and G(M1)-ELISA. RESULTS: In comparison with the reported LTB and CTB sequences, the nucleotide sequence homologies of the cloned LTB gene and CTB gene were from 99.12% approximate, equals 99.71% and 98.54% approximate, equals 99.42%, while their putative amino acid sequence homologies were as high as 97.58% approximate, equals 99.19% and 96.77% approximate, equals 99.19%. The expression outputs of LTB and CTB fusion proteins in pET32a LTB BL21DE3 and pET32a-CTB-BL21DE3 systems were approximately 30% and 10% of the total bacterial proteins, respectively. The LTB and CTB fusion proteins were able to combine with bovine G(M1) confirmed by ELISA. CONCLUSION: The expression systems of LTB and CTB genes have been successfully established. Both the expressed LTB and CTB fusion proteins possess mucosal adjuvant immunoactivity.