Antimicrobial activity of Lactobacillus reuteri DPC16 supernatants against selected food borne pathogens

Lactobacillus reuteri DPC16 is a human-isolated strain recently patented in New Zealand. The antimicrobial activity of cell-free supernatants from different fermentation processes, with or without glycerol supplementation was studied. When grown in just MRS broth, the cultural supernatant significantly inhibited the growth of selected food-borne pathogens, possibly due to acidic effect as this activity was pH-dependent. The cell-free supernatants from secondary fermentation of DPC16 resting cells in glycerol-supplemented media have shown very different antimicrobial activities. A very potent antimicrobial activity gradually developed during the fermentation process which was observed only when growing in MRS-glycerol broth (such supernatant is denoted MRSg). This strong antimicrobial activity was pH-independent, dose-dependant and affected both Gram-negative and Gram-positive pathogens. Reuterin detected in MRSg is believed to be responsible for these activities. The susceptibility of the selected pathogens (grown to stationary phase) to MRSg was tested and found that exposure to MRSg for 180 min led to a significant reduction in cell viability in all pathogens. These results suggest that this is a reuterin-producing strain, which has potent antimicrobial activity against both Gram-negative and Gram-positive pathogens. These findings have indicated a clear potential of this novel strain in industrial applications.     

Comparative analysis on the diversity of <Emphasis Type="Italic">Auricularia auricula</Emphasis>-<Emphasis Type="Italic">judae</Emphasis> by physiological characteristics,somatic incompatibility and TRAP fingerprinting

Phenotypic traits (physiological characteristics and somatic incompatibility) and genotypic traits (target region amplification polymorphism TRAP) were used to study the diversity of 32 main cultivars of Auricularia auricula-judae in China. Twenty seven important and stable physiological indexes were evaluated; somatic incompatibility test (SIT) reaction was described from three aspects: type, pigment, and intensity; 16 pairs of TRAP primer combinations produced 535 unambiguous and reproducible DNA fragments, of these 524 (97.9%) were polymorphic. Dendrograms were constructed by Unweighted Pair-group Method with Arithmetic Averages (UPGMA) method, and the principal coordinate analysis (PCO) of the three methods (physiological characteristics, SIT intensity and TRAP) exhibited similar clustered patterns, revealing that all the tested strains could be divided into three distinct groups, each of which was correlated with different geographical regions. Most strains originated from the same area were with a narrow genetic basis and could possibly be domesticated from the local wild-type strains, some strains were suspected to be synonymous. The grouping information obtained in the present work provides significant information for further genetic improvement of A. auricula-judae.     

Identification of alkaline stress-responsive genes of CBL family in sweet sorghum (Sorghum bicolor L.)

Calcineurin B-like proteins play important roles in the calcium perception and signal transduction of abiotic stress. In this study, the bioinformatic analysis of molecular characteristics of Sorghum bicolor calcineurin B-like protein (SbCBL) revealed that sequences of SbCBL are highly conserved, and most SbCBLs have three typical EF-hands structures. Among the SbCBL proteins, four of which, SbCBL01, 04, 05, 08, have a conserved N-myristoylation domain. Stress-responsive and phytohormone-responsive cis-elements were found in the promoter regions of SbCBL genes. Real-time quantitative polymerase chain reaction (RTqPCR) analysis showed that SbCBL genes have different tissue-specific expression patterns under normal growth conditions in sweet sorghum (Sorghum bicolor L. Moench). Interestingly, when treated with sodium carbonate, SbCBL genes also show various sodium carbonate stress responsive patterns in sweet sorghum seedlings. These results suggest that SbCBLs may participate in regulating sodium carbonate stress-specific cellular adaptation responses and influencing growth and developmental patterns in sweet sorghum.     

Effects of domestic wastewater slow infiltration on the growth of poplar 'Zhonglin 2001' plantation

A slow infiltration experiment with different hydraulic loads (0, 3, 6, 9, 12, and 15 cm per week) of domestic wastewater was conducted in a 'Zhonglin 2001' poplar plantation to study the effects of the wastewater slow infiltration on the growth of the plantation. Comparing with the control (0 cm), the other five treatments increased the soil organic matter, total N, total P, total K, and Na+ contents in the plantation averagely by 1.940 g x kg(-1), 0.115 g x kg(-1), 0.029 g x kg(-1), 1.454 g x kg(-1) and 0.030 g x kg(-1), respectively. At lower hydraulic loads (3-12 cm per week), the poplar biomass growth and the N, P and Na+ contents in different poplar organs averagely increased by 17.583 t x hm(-2) x a(-1), 3.086 g x kg(-1), 0.645 g x kg(-1), and 0.121 g x kg(-1), with the maximum (36.252 t x hm(-2) x a(-1), 13.162 g x kg(-1), 5.137 g x kg(-1), and 0.361 g x kg(-1), respectively) at hydraulic loads 6-12 cm per week. The further increase of the hydraulic load decreased the poplar biomass growth and the N, P and Na+ contents in different poplar organs. The K content in different poplar organs decreased with increasing hydraulic load. Treating with domestic wastewater increased the leaf length, decreased the leaf asymmetry, and delayed leaf-falling. At high hydraulic load (15 cm per week), the higher soil Na+ and water contents would threat the poplar growth. The proper domestic wastewater hydraulic loads for the growth of poplar 'Zhonglin 2001' plantation would be 3-12 cm per week.     

Spectrofluorimetric determination of bilirubin in serum samples

A new spectrofluorimetric method was developed for determination of trace amount of bilirubin. Using oxytetracycline–Eu³⁺ as a fluorescent probe, in the buffer solution of pH = 7.3, bilirubin can reduce remarkably the fluorescence intensity of the oxytetracycline–Eu³⁺ complex at λ = 612 nm and the reduced fluorescence intensity was in proportion to the concentration of bilirubin. Optimum conditions for the determination of bilirubin were also investigated. The linear range and limit of detection for the determination of bilirubin were 5.0 × 10^?7, 3.0 × 10^?5 and 7.7 × 10^?8 mol L^?1, respectively. This method is simple, practical and relatively free of interference from coexisting substances and can be successfully applied to assess bilirubin in serum samples and compared with the modified Jendrassik–Grof method in clinical analysis. The quenching mechanism of the fluorescence intensity in the system is also discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

A defensin‐like antimicrobial peptide from the venoms of spider,Ornithoctonus hainana

The defensin‐like antimicrobial peptides have been characterized from various other arthropods including insects, scorpions, and ticks. But no natural spider defensin‐like antimicrobial peptides have ever been isolated from spiders, except couple of cDNA and DNA sequences of five spider species revealed by previous genomic study. In this work, a defensin‐like antimicrobial peptide named Oh‐defensin was purified and characterized from the venoms of the spider, Ornithoctonus hainana. Oh‐defensin is composed of 52 amino acid (aa) residues including six Cys residues that possibly form three disulfide bridges. Its aa sequence is MLCKLSMFGAVLGV PACAIDCLPMGKTGGSCEGGVCGCRKLTFKILWDKKFG. By BLAST search, Oh‐defensin showed significant sequence similarity to other arthropod antimicrobial peptides of the defensin family. Oh‐defensin exerted potent antimicrobial activities against tested microorganisms including Gram‐positive bacteria, Gram‐negative bacteria, and fungi. The cDNA encoding Oh‐defensin precursor was also cloned from the cDNA library of O. hainana. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Flower-specific expression of <Emphasis Type="Italic">Arabidopsis</Emphasis><Emphasis Type="Italic">PCS1</Emphasis> driven by <Emphasis Type="Italic">AGAMOUS</Emphasis> second intron in tobacco decreases the fertility of transgenic plants

The PROMOTION OF CELL SURVIVAL 1 (PCS1) gene, encoding an aspartic protease, has an important role in determining the fate of cells in embryonic development and reproduction processes in Arabidopsis. To explore the potential function of the PCS1 gene in generating reproductive sterility, we placed the PCS1 gene under the control of an 1,869-bp nucleotide sequence from the 3′ end of the second intron (AG-I) of Arabidopsis AGAMOUS and CaMV 35S (–60) minimal promoter [AG-I-35S (–60)::PCS1], and introduced it into tobacco. RT–PCR results demonstrated that the PCS1 gene driven by AG-I-35S (–60) chimeric promoter was expressed only in anthers and carpels in the reproductive tissues of transgenic tobacco. Compared to wild-type plants, all AG-I-35S (–60) and AG-I-35S (–60)::PCS1 transgenic lines showed a normal phenotype throughout the vegetative growth phase. However, during the reproductive stage, most AG-I-35S (–60)::PCS1 transgenic plant anthers displayed delayed dehiscence, failed dehiscence, petalody and hypoplasia, and the pollen grains had different shapes and sizes with a distorted, shrunken, or collapsed morphology. Moreover, three transgenic lines, PCS1-1, PCS1-3 and PCS1-4, showed higher sterility than wild-type and AG-I-35S (–60) transgenic plants, respectively. These results showed that the construct of AG-I-35S (–60)::PCS1 was partially effective at preventing seed set and provided a novel sterility strategy.