Bacillus velezensis DJ1 exhibits broad-spectrum antagonistic activity against diverse phytopathogenic fungi, while its biocontrol mechanisms against Fusarium graminearum, the causal agent of maize stalk rot, remain poorly characterized. In this study, we integrated genomics and transcriptomics to elucidate the antifungal mechanisms of strain DJ1. The results demonstrated that DJ1 inhibited F. graminearum with the efficacy of 64.4%, while its polyketide crude extract achieved the control efficacy of 55% in pot experiments against this disease. Whole-genome sequencing revealed a single circular chromosome (3 929 792 bp, GC content of 47%) harboring 12 biosynthetic gene clusters for secondary metabolites, six of which encoded known antimicrobial compounds (macrolactin H, bacillaene, difficidin, surfactin, fengycin, and bacilysin). Transcriptomic analysis identified 243 differentially expressed genes (152 upregulated and 91 downregulated, P < 0.05), which were potentially associated with the antagonistic activity against F. graminearum. KEGG enrichment analysis highlighted activation (P < 0.05) of cysteine/methionine metabolism, pentose phosphate pathway, and polyketide biosynthesis pathways, indicating that DJ1 employed synergistic strategies involving antimicrobial compound synthesis, energy metabolism enhancement, and nutrient competition to suppress pathogens. This study provides a theoretical foundation for developing novel microbial resources and application technologies to combat phytopathogenic fungi.
Fusarium/drug effects* ; Bacillus/metabolism* ; Plant Diseases/prevention & control* ; Antifungal Agents/pharmacology* ; Genomics ; Zea mays/microbiology* ; Transcriptome ; Gene Expression Profiling ; Antibiosis ; Multigene Family ; Multiomics

High-throughput transcriptomics technologies have been widely used to study plant transcriptional reprogramming during the process of plant defense responses, and a large quantity of gene expression data have been accumulated in public repositories. However, utilization of these data is often hampered by the lack of standard metadata annotation. In this study, we curated 2444 public pathogenesis-related gene expression samples from the model plant Arabidopsis and three major crops (maize, rice, and wheat). We organized the data into a user-friendly database termed as PlaD. Currently, PlaD contains three key features. First, it provides large-scale curated data related to plant defense responses, including gene expression and gene functional annotation data. Second, it provides the visualization of condition-specific expression profiles. Third, it allows users to search co-regulated genes under the infections of various pathogens. Using PlaD, we conducted a large-scale transcriptome analysis to explore the global landscape of gene expression in the curated data. We found that only a small fraction of genes were differentially expressed under multiple conditions, which might be explained by their tendency of having more network connections and shorter network distances in gene networks. Collectively, we hope that PlaD can serve as an important and comprehensive knowledgebase to the community of plant sciences, providing insightful clues to better understand the molecular mechanisms underlying plant immune responses. PlaD is freely available at http://systbio.cau.edu.cn/plad/index.php or http://zzdlab.com/plad/index.php.
Arabidopsis ; genetics ; Databases, Genetic ; Gene Expression Profiling ; Gene Expression Regulation, Plant ; Gene Regulatory Networks ; Genes, Plant ; Host-Pathogen Interactions ; genetics ; Oryza ; genetics ; Plant Immunity ; genetics ; Plants ; genetics ; microbiology ; Transcriptome ; genetics ; Triticum ; genetics ; User-Computer Interface ; Zea mays ; genetics

Production of bioethanol using starch as raw material has become a very prominent technology. However, phytate in the raw material not only decreases ethanol production efficiency, but also increases phosphorus discharge. In this study, to decrease phytate content in an ethanol fermentationprocess, Saccharomyces cerevisiae was engineered forheterologous expression of phytase on the cell surface. The phy gene encoding phytase gene was fused with the C-terminal-half region of α-agglutinin and then inserted downstream of the secretion signal gene, to produce a yeast surface-display expression vector pMGK-AG-phy, which was then transformed into S. cerevisiae. The recombinant yeast strain, PHY, successfully displayed phytase on the surface of cells producing 6.4 U/g wet cells and its properties were further characterized. The growthrate and ethanol production of the PHY strain were faster than the parent S. cerevisiae strain in the fermentation medium by simultaneous saccharification and fermentation. Moreover, the phytate concentration decreased by 91% in dry vinasse compared to the control. In summary, we constructed recombinant S. cerevisiae strain displaying phytase on the cell surface, which could effectively reduce the content of phytate, improve the utilization value of vinasse and reduce the discharge of phosphorus. The strain reported here represents a useful novel engineering platform for developing an environment-friendly system for bioethanol production from a corn substrate.
6-Phytase ; metabolism ; Biofuels ; Ethanol ; chemistry ; Fermentation ; Industrial Microbiology ; Saccharomyces cerevisiae ; metabolism ; Starch ; chemistry ; Zea mays ; chemistry

OBJECTIVETo elucidate the natural occurrence of masked deoxynivalenol (DON-3-G) and other multi-mycotoxins in cereals from parts of China.

METHODSA total of 446 corn and wheat samples harvested in 2007 and 2008 collected from Henan, Hebei, Guangxi, Anhui, Sichuan, Chongqing and Jiangsu provinces were analyzed for DON-3-G and other multi-mycotoxins (including deoxynivalenol (DON), zearalenone (ZEN), nivalenol (NIV), et al) by UPLC-MS/MS.

RESULTSCorn and wheat samples were mainly contaminated by DON and its derivatives as well as ZEN.88% (169/192) of wheat samples were positive for DON (range: 1.5 - 590.7 µg/kg; median: 30.8 µg/kg); 22.9% (44/192) of wheat samples were contaminated with ZEN (range: 1.7 - 3425.0 µg/kg; median: 8.0 µg/kg) and six samples contained ZEN concentration higher than the ZEN tolerance limit of 60 µg/kg. DON was detected in 50.5% (103/204) corn samples (range: 1.6 - 4374.4 µg/kg; median: 94.9 µg/kg); Seven samples contained DON exceeding the tolerance limit of 1000 µg/kg for DON. Additionally, ZEN was found in 41.7% (85/204) corn samples with the concentration between 1.6 µg/kg and 4808.7 µg/kg (median: 48.5 µg/kg) and there were 37 corn samples with ZEN level in the excess of tolerance limit for ZEN (60 µg/kg). DON-3-G was detected in corn and wheat samples for the first time in China with the median level of 21.4 µg/kg and 34.6 µg/kg for wheat and corn, respectively. Wheat was more heavily contaminated with DON-3-G than both 3-acetyl-DON (3-A-DON, median: 4.1 µg/kg) and 15-acetyl-DON (15-A-DON, median: 3.1 µg/kg) (t values were 5.111 and 5.966, respectively, both P values < 0.01). While, the level of 15-A-DON (median: 48.6 µg/kg) in corn was higher than 3-A-DON (median: 6.8 µg/kg) (t = -3.579, P < 0.01). The concentration of DON, DON-3-G, 3-A-DON, 15-A-DON and ZEN in corn were higher than that in wheat (Z values were -3.492, -1.960, -2.467, -8.711 and -6.272, respectively, all P values < 0.05). Wheat (median: 29.0 µg/kg) contained higher NIV in comparison with corn (median: 18.2 µg/kg, Z = -2.086, P < 0.05).

CONCLUSIONWheat and corn samples from parts of China were contaminated with multi-mycotoxins and DON was the predominant;in comparison of wheat, corn was more heavily contaminated with DON, DON-3-G, 3-A-DON, 15-A-DON and ZEN.

China ; Edible Grain ; chemistry ; microbiology ; Food Contamination ; Food Microbiology ; Fusarium ; isolation & purification ; Mycotoxins ; isolation & purification ; Trichothecenes ; isolation & purification ; Triticum ; chemistry ; microbiology ; Zea mays ; chemistry ; microbiology

Corn, one of the most important forage crops worldwide, has proven to be a useful expression vehicle due to the availability of established transformation procedures for this well-studied plant. The exotoxin Apx, a major virulence factor, is recognized as a common antigen of Actinobacillus (A.) pleuropneumoniae, the causative agent of porcine pleuropneumonia. In this study, a cholera toxin B (CTB)-ApxIIA#5 fusion protein and full-size ApxIIA expressed in corn seed, as a subunit vaccine candidate, were observed to induce Apx-specific immune responses in mice. These results suggest that transgenic corn-derived ApxIIA and CTB-ApxIIA#5 proteins are potential vaccine candidates against A. pleuropneumoniae infection.
Actinobacillus Infections/microbiology/*prevention & control ; Actinobacillus pleuropneumoniae ; Animals ; Antigens, Bacterial/immunology ; Bacterial Proteins/*immunology ; Bacterial Vaccines/*immunology ; Cholera Toxin/*chemistry ; Female ; Hemolysin Proteins/*immunology ; Immunization, Secondary ; Mice ; Mice, Inbred ICR ; Plants, Genetically Modified ; Zea mays/*genetics

Biomass carbohydrates assimilation and lipid accumulation by Mortierella isabellina M2 strain were investigated. Corn fiber hydrolysate was specially studied. The results showed M. isabellina M2 strain achieved growth and lipid accumulation while glucose, xylose, mannose and arabinose were introduced as single carbon source, respectively. When M. isabellina M2 strain was cultivated on corn fiber hydrolysate with 6% sugars concentration, the biomass reached 18.2 g/L, the lipid content of dry mycelia was 45.7%, and the lipid yield achieved 8.3 g/L. It provided a promising perspective for microbial oils production with biomass hydrolysates.
Biomass ; Carbohydrate Metabolism ; Carbon ; metabolism ; Fermentation ; Industrial Microbiology ; methods ; Lipids ; biosynthesis ; Mortierella ; metabolism ; Zea mays ; metabolism

This research aimed to study the effect of distillage recycling on ethanol fermentation, the key glycolytic enzymes and cell composition of the self-flocculating yeast. With the self-flocculating yeast SPSC01 and medium composed of 220 g/L glucose, 8 g/L yeast extract and 6 g/L peptone, continuous ethanol fermentation was carried out at the dilution rate of 0.04 h(-1) with a 1.5 L tank bioreactor. Fermentation broth was collected every 3 days, and ethanol and other volatile byproducts were removed by distillation, but the stillage with high boiling byproducts was recycled to prepare the medium instead of fresh water. The system was run for 20 days, during which ethanol and biomass concentrations in the effluent decreased continuously, indicating the significant inhibition of the high boiling byproducts accumulated within the system. Thus, the activities of the key enzymes of the glycolytic pathway: hexokinase, 6-phosphofructose kinase, and pyruvate kinase were analyzed, and it was observed that all of them were inhibited. Furthermore, the biosynthesis of the stress response metabolites glycerol and trehalose was investigated, and it was found that glycerol production that can protect yeast cells against osmotic pressure stress was enhanced, but trehalose biosynthesis that can protect yeast cells against ethanol inhibition was not improved, correspondingly. And in the meantime, the biosynthesis of the major intracellular components proteins and hydrocarbons was adjusted, correspondingly.
Bioreactors ; microbiology ; Ethanol ; metabolism ; Fermentation ; Flocculation ; Glycerol ; metabolism ; Glycolysis ; Hexokinase ; metabolism ; Industrial Microbiology ; methods ; Phosphofructokinase-1 ; metabolism ; Saccharomyces cerevisiae ; enzymology ; genetics ; metabolism ; Schizosaccharomyces ; enzymology ; genetics ; metabolism ; Trehalose ; metabolism ; Triticum ; metabolism ; Zea mays ; metabolism

Biohydrogen production from corncob by dark fermentation was reported for the first time. The effects of the pretreatment condition, substrate concentration and initial pH on the hydrogen production were investigated in batch cultivations. The maximum hydrogen yield of 107.9 mL/g-TVS and hydrogen production rate of 4.2 mL/g-TVS .h(-) were obtained under the condition of 1% HCl pretreating substrate for 30 min, 10 g/L substrate concentration and initial pH8.0. The content of hemicellulose in corncob decreased significantly from 42.2% to 3.0% after HC1 pretreatment. The contents of cellulose, hemicellulose and lignin in the acid pretreated corncob decreased slightly in hydrogen producing process. The results indicate that the acid pretreatment of the substrate plays a key role in the conversion of corncob into biohydrogen. Fourier transform infrared spectroscopy (FTIR) was used to study the changes in the corncob composition during the treatment of chemical-microbial process. It was shown that the amorphous domains of cellulose and hemicellulose were hydrolyzed into fermentable asccharides through HCl pretreatment and the microorganisms had a devastating effect on the crystallinitiy of the cellulose.
Anaerobiosis ; Bioelectric Energy Sources ; Bioreactors ; microbiology ; Fermentation ; Hydrogen ; metabolism ; Spectroscopy, Fourier Transform Infrared ; Zea mays ; metabolism

Rice bacterial leaf streak,caused by Xanthomonas oryzae pv. oryzicola is a destructive bacterial disease in China. Single-gene resistance to X. oryzae pv. oryzicola has not been found in rice germplasm. A cloned non-host gene from maize with resistance to bacterial leaf streak, Rxo1, was transferred into four Chinese rice varieties through an Agrobacterium-mediated system, including Zhonghua11, 9804, C418 and Minghui86. PCR and Southern analysis of the transgenic plants revealed the integration of the Rxo1 gene into the rice genomes. The integrated Rxo1 was stably inherited, and segregated in a 3:1 (Resistance:Susceptible) ratio in the selfed T1 generations derived from some T0 plants, indicating that Rxo1 inherited as a dominate gene in rice. Transgenic T0 plants and PCR-positive T1 plants were resistant to X. oryzae pv. oryzicola on the basis of artificial inoculation.
Bacterial Proteins ; genetics ; metabolism ; Genes, Plant ; genetics ; Oryza ; genetics ; Plant Diseases ; genetics ; microbiology ; Plants, Genetically Modified ; genetics ; Rhizobium ; genetics ; Transformation, Genetic ; Xanthomonas ; genetics ; Zea mays ; genetics ; microbiology

OBJECTIVETo realize the contamination of total aflatoxins in corn, peanut, rice, walnut and pine nut in China, and provide the base data for establishing a China tolerance limit standard and an international control practice for total aflatoxins.

METHODSThe samples of corn, peanut, rice, walnut and pine nut from Chongqing, Fujian, Guangdong, Guangxi, Hubei, Jiangsu, Shanghai and Zhejiang provinces and municipalities were collected randomly from markets, with the totally 284 samples. The samples were grounded and added to acetonitrile/water mixture. After filtering, the extract was transferred into a purifying column and pressed slowly. Then the purified liquid was derivatized with trifluoroacetic acid (TFA) and detected by using a high performance liquid chromatography (HPLC).

RESULTSThere was 70.27% corn having been detected out an average level of aflatoxins of 36.51 microg/kg and the highest level was 1098.36 microg/kg. At the same time, there was 14.86% corn exceeding the China national tolerance limit. In peanut, the aflatoxins detected rate was 24.24%. The average level was 80.27 microg/kg and the highest level was 437.09 microg/kg. While there was 3.03% peanut exceeding the China national and Codex tolerance limits. All of the rice, walnut and pine nut samples met the China tolerance limit for aflatoxins.

CONCLUSIONCorn and peanut might be the severely contaminated foods with aflatoxins in China. The aflatoxin B(1) in foods might be can not delegate the contamination of aflatoxins completely. Surveillance of total aflatoxins in foods suggested an actual need of establishing the China national and international standards for total aflatoxins.

Aflatoxins ; analysis ; Arachis ; China ; Chromatography, High Pressure Liquid ; Food Contamination ; analysis ; prevention & control ; Food Microbiology ; Nuts ; Oryza ; Zea mays