Survival of Escherichia coli O157:H7 in Soils from Vegetable Fields with Different Cultivation Patterns

Escherichia coli O157:H7 survived longer in soils from plastic-greenhouse cultivation than soils from the open field. Soil pH, organic carbon levels, and the ratio of bacterial phospholipid fatty acids (PLFAs) to fungal PLFAs played the significant roles in survival of O157:H7. Greater attention should be paid to the control of pathogen contamination under conditions of plastic-greenhouse cultivation.     

Characterization and expression of gamma-interferon-inducible lysosomal thiol reductase (GILT) gene in rainbow trout (Oncorhynchus mykiss) with implications for GILT in innate immune response

The interferon-γ-inducible lysosomal thiol reductase (GILT) has been demonstrated to play an important role in the processing and presentation of MHC class II-restricted antigen (Ag) by catalyzing disulfide bond reduction. In this study, a rainbow trout cDNA (designated as rGILT) was cloned and identified from Oncorhynchus mykiss. The open reading frame of rGILT consists of 759 bases encoding a protein of 253 amino acids with an estimated molecular mass of 28.23 kDa and a theoretical isoelectric point of 4.94. The rGILT exhibited a characteristic GILT signature sequence CQHGX₂ECX₂NX₄C and CXXC motif. Phylogenetic analysis suggested that rGILT had been derived from a common ancestor with other GILT proteins. RT-PCR results showed that rGILT and rIFN-γ (rainbow trout IFN-γ) mRNA was expressed in a tissue-specific manner and obviously up-regulated in splenocytes and the cells from head kidney after induction with LPS. Recombinant rGILT fused with His6 tag was efficiently expressed in Escherichia coli BL21 (DE3) and purified by Ni-NTA affinity chromatography. Further study revealed that rGILT was capable of catalyzing the reduction of the interchain disulfide bonds from intact IgG. This study shows that rGILT may be involved in the immune response to bacteria challenge and maintain first line of innate immune defense at basal level in O. mykiss. It also provides the basis for investigating on the role of GILT using O. mykiss as an animal model for related studies.     

Assessment of Microbiome Variation During the Perioperative Period in Liver Transplant Patients: a Retrospective Analysis

Understanding the composition of the microbial populations in the intestines of liver transplant patients is important to preventing postoperative infection. We investigated the relationship between the risk of postoperative infection and variation in the predominant fecal microbial composition during the perioperative period. We prospectively analyzed the predominant intestinal microbiome of five asymptomatic adult carriers of hepatitis B virus (as controls without any antibiotics) at four weekly follow-up visits and 12 patients before operation and at three weekly postoperative follow-up visits within the first month. Analysis was by denaturing gradient gel electrophoresis (DGGE) and sequencing with digital processing of DGGE profiles using BioNumerics software. Our results showed that the predominant intestinal microbial diversity decreased substantially in eight patients during the perioperative period. Among these, five patients experienced infection with a postoperative hospital stay of more than 30 days. The rest of the four patients who experienced shorter postoperative hospital stays showed only slight variation in predominant intestinal bacterial composition and temporal stability similar to asymptomatic controls. Postoperative fecal DGGE profiles showed mostly bands assigned to Bacteroides and Firmicutes. We conclude that an empiric prophylaxis strategy that destructs gut microecological balance will not be effective in reducing the risk of postoperative infection. Instead, the destruction of intestinal microbiota might result in the appearance of opportunistic pathogens such as Bifidobacterium dentium which rarely appears in the intestinal DGGE profiles of normal humans. Cognizance of the variation of intestinal microbial profiles during the perioperative period is a critical aspect of caring for liver transplant recipients.     

Major QTL for Fusarium crown rot resistance in a barley landrace

Fusarium crown rot (FCR) is a serious cereal disease in semi-arid regions worldwide. In assisting the effort of breeding cultivars with enhanced resistance, we identified several barley genotypes with high levels of FCR resistance. One of these genotypes, AWCS079 which is a barley landrace originating from Japan, was investigated by developing and assessing three populations of recombinant inbred lines. Two QTL, one located on the long arm of chromosome 1H (designated as Qcrs.cpi-1H) and the other on 3HL (designated as Qcrs.cpi-3H), were found to be responsible for the FCR resistance of this genotype. Qcrs.cpi-1H is novel as no other FCR loci have been reported on this chromosome arm. Qcrs.cpi-3H co-located with a reduced height (Rht) locus and the effectiveness of the former was significantly affected by the latter. The total phenotypic variance explained by these two QTL was over 60 %. Significant effects were detected for each of the QTL in each of the three populations assessed. The existence of these loci with major effects should not only facilitate breeding and exploitation of FCR-resistant barley cultivars but also their further characterization based on fine mapping and map-based gene cloning.     

Anther extrusion and plant height are associated with Type I resistance to Fusarium head blight in bread wheat line ‘Shanghai-3/Catbird’

Fusarium head blight (FHB) is a destructive wheat disease of global importance. Resistance breeding depends heavily on the Fhb1 gene. The CIMMYT line Shanghai-3/Catbird (SHA3/CBRD) is a promising source without this gene. A recombinant inbred line (RIL) population from the cross of SHA3/CBRD with the German spring wheat cv. Naxos was evaluated for FHB resistance and related traits in field trials using spray and spawn inoculation in Norway and point inoculation in China. After spray and spawn inoculation, FHB severities were negatively correlated with both anther extrusion (AE) and plant height (PH). The QTL analysis showed that the Rht-B1b dwarfing allele co-localized with a QTL for low AE and increased susceptibility after spawn and spray inoculation. In general, SHA3/CBRD contributed most of the favorable alleles for resistance to severity after spray and spawn inoculation, while Naxos contributed more favorable alleles for reduction in FDK and DON content and resistance to severity after point inoculation. SHA3/CBRD contributed a major resistance QTL close to the centromere on 2DLc affecting FHB severity and DON after all inoculation methods. This QTL was also associated with AE and PH, with high AE and tall alleles contributed by SHA3/CBRD. Several QTL for AE and PH were detected, and low AE or reduced PH was always associated with increased susceptibility after spawn and spray inoculation. Most of the other minor FHB resistance QTL from SHA3/CBRD were associated with AE or PH, while the QTL from Naxos were mostly not. After point inoculation, no other QTL for FHB traits was associated with AE or PH, except the 2DLc QTL which was common across all inoculation methods. Marker-assisted selection based on the 2DLc QTL from SHA3/CBRD combined with phenotypic selection for AE is recommended for resistance breeding based on this valuable source of resistance.     

A Method for Molecular Analysis of Catalase Gene Diversity in Seawater

Catalase plays an important role in the metabolism of marine bacteria and has potential impact on the marine environment. Four PCR primers were designed to amplify the catalase gene fragments in marine bacteria by applying metagenomic DNA from Yellow Sea surface water as the template. Of the four reproducible target PCR products, the longest one with 900 bp were chosen for catalase gene library construction by the T-vector and the white Escherichia coli colonies in the library was screened through restriction-digesting the reamplified insert fragments by the selected restriction endonuclease MboI, and then the bands of the resulting products were displayed in the agarose gel by electrophoresis. The unique restriction fragment length polymorphism (RFLP) pattern was selected and the corresponding catalase gene fragments were sequenced, which verified that every unique RFLP pattern represented one type of catalase. This PCR–RFLP method above was established to investigate the bacterial catalase diversity in seawater.     

Linking carbon and nitrogen metabolism to depth distribution of submersed macrophytes using high ammonium dosing tests and a lake survey

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Microbiological Identification and Analysis of Swine Lungs Collected from Carcasses in Swine Farms, China

The primary objective of this 3 years study was to determine the prevalence of porcine pathogens of the lungs of swine in swine farms in southern China. A total of 5,420 samples were collected from 200 swine farms. The bacterium that was most commonly isolated was Streptococcus suis, with 10.24 % of the samples being positive, 114 lungs (2.1 %) were positive for pseudorabies virus and 263 (4.85 %) were positive for classical swine fever virus; much lower than positive for PRRSV (15.1 %, p = 0.023) and PCV2 (13.8 %, p = 0.038). lungs that were positive for PRRSV and/or PCV-2 have significantly increased odds of being positive for any of the S. suis (9.79 vs. 0.44 %, p = 0.003).