Identification and Antimicrobial Activity Detection of Lactic Acid Bacteria Isolated from Corn Stover Silage

Dongxia Li,Kuikui Ni,Huili Pang,Yanping Wang,Yimin Cai,Qingsheng Jin 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.5

A total of 59 lactic acid bacteria (LAB) strains were isolated from corn stover silage. According to phenotypic and chemotaxonomic characteristics, 16S ribosomal DNA (rDNA) sequences and recA gene polymerase chain reaction amplification, these LAB isolates were identified as five species: Lactobacillus (L.) plantarum subsp. plantarum, Pediococcus pentosaceus, Enterococcus mundtii, Weissella cibaria and Leuconostoc pseudomesenteroides, respectively. Those strains were also screened for antimicrobial activity using a dual-culture agar plate assay. Based on excluding the effects of organic acids and hydrogen peroxide, two L. plantarum subsp. plantarum strains ZZU 203 and 204, which strongly inhibited Salmonella enterica ATCC 43971T, Micrococcus luteus ATCC 4698T and Escherichia coli ATCC 11775T were selected for further research on sensitivity of the antimicrobial substance to heat, pH and protease. Cell-free culture supernatants of the two strains exhibited strong heat stability (60 min at 100°C), but the antimicrobial activity was eliminated after treatment at 121°C for 15 min. The antimicrobial substance remained active under acidic condition (pH 2.0 to 6.0), but became inactive under neutral and alkaline condition (pH 7.0 to 9.0). In addition, the antimicrobial activities of these two strains decreased remarkably after digestion by protease K. These results preliminarily suggest that the desirable antimicrobial activity of strains ZZU 203 and 204 is the result of the production of a bacteriocin-like substance, and these two strains with antimicrobial activity could be used as silage additives to inhibit proliferation of unwanted microorganism during ensiling and preserve nutrients of silage. The nature of the antimicrobial substances is being investigated in our laboratory.

Identification and Antimicrobial Activity Detection of Lactic Acid Bacteria Isolated from Corn Stover Silage

Li, Dongxia,Ni, Kuikui,Pang, Huili,Wang, Yanping,Cai, Yimin,Jin, Qingsheng Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.5

A total of 59 lactic acid bacteria (LAB) strains were isolated from corn stover silage. According to phenotypic and chemotaxonomic characteristics, 16S ribosomal DNA (rDNA) sequences and recA gene polymerase chain reaction amplification, these LAB isolates were identified as five species: Lactobacillus (L.) plantarum subsp. plantarum, Pediococcus pentosaceus, Enterococcus mundtii, Weissella cibaria and Leuconostoc pseudomesenteroides, respectively. Those strains were also screened for antimicrobial activity using a dual-culture agar plate assay. Based on excluding the effects of organic acids and hydrogen peroxide, two L. plantarum subsp. plantarum strains ZZU 203 and 204, which strongly inhibited Salmonella enterica ATCC $43971^T$, Micrococcus luteus ATCC $4698^T$ and Escherichia coli ATCC $11775^T$ were selected for further research on sensitivity of the antimicrobial substance to heat, pH and protease. Cell-free culture supernatants of the two strains exhibited strong heat stability (60 min at $100^{\circ}C$), but the antimicrobial activity was eliminated after treatment at $121^{\circ}C$ for 15 min. The antimicrobial substance remained active under acidic condition (pH 2.0 to 6.0), but became inactive under neutral and alkaline condition (pH 7.0 to 9.0). In addition, the antimicrobial activities of these two strains decreased remarkably after digestion by protease K. These results preliminarily suggest that the desirable antimicrobial activity of strains ZZU 203 and 204 is the result of the production of a bacteriocin-like substance, and these two strains with antimicrobial activity could be used as silage additives to inhibit proliferation of unwanted microorganism during ensiling and preserve nutrients of silage. The nature of the antimicrobial substances is being investigated in our laboratory.

Fermentation characteristics, chemical composition and microbial community of tropical forage silage under different temperatures

Dongxia Li,Kuikui Ni,Yingchao Zhang,Yanli Lin,Fuyu Yang 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.5

Objective: In tropical regions, as in temperate regions where seasonality of forage production occurs, well-preserved forage is necessary for animal production during periods of forage shortage. However, the unique climate conditions (hot and humid) and forage characteristics (high moisture content and low soluble carbohydrate) in the tropics make forage preservation more difficult. The current study used natural ensiling of tropical forage as a model to evaluate silage characteristics under different temperatures (28°C and 40°C). Methods: Four tropical forages (king grass, paspalum, white popinac, and stylo) were ensiled under different temperatures (28°C and 40°C). After ensiling for 30 and 60 days, samples were collected to examine the fermentation quality, chemical composition and microbial community. Results: High concentrations of acetic acid (ranging from 7.8 to 38.5 g/kg dry matter [DM]) were detected in silages of king grass, paspalum and stylo with relatively low DM (ranging from 23.9% to 30.8% fresh material [FM]) content, acetic acid production was promoted with increased temperature and prolonged ensiling. Small concentrations of organic acid (ranging from 0.3 to 3.1 g/kg DM) were detected in silage of white popinac with high DM content (50.8% FM). The microbial diversity analysis indicated that Cyanobacteria originally dominated the bacterial community for these four tropical forages and was replaced by Lactobacillus and Enterobacter after ensiling. Conclusion: The results suggested that forage silages under tropical climate conditions showed enhanced acetate fermentation, while high DM materials showed limited fermentation. Lactobacillus and Enterobacter were the most probable genera responsible for tropical silage fermentation.

Interleukin-17 Indirectly Promotes M2 Macrophage Differentiation through Stimulation of COX-2/PGE2 Pathway in the Cancer Cells

Qingli Li,Lunxu Liu,Qiuyang Zhang,Sen Liu,Dongxia Ge,Zongbing You 대한암학회 2014 Cancer Research and Treatment Vol.46 No.3

PurposeInterleukin-17 (IL-17) is a proinflammatory cytokine that plays important roles ininflammation, autoimmunity, and cancer. The purpose of this study was to determineif IL-17 indirectly regulates macrophage differentiation through up-regulation ofcyclooxygenase-2 (COX-2) expression in the cancer cell lines. Materials and MethodsHuman cervical cancer HeLa, human lung cancer A549, and mouse prostate cancerMyc-CaP/CR cell lines were treated with recombinant IL-17; Western blot analysis,enzyme-linked immunosorbent assay, and quantitative real-time polymerase chainreaction analysis were utilized to examine the cellular responses. ResultsIL-17 up-regulated expression of COX-2 mRNA and protein in HeLa, A549, and Myc-CaP/CR cell lines. IL-17’s effects were mediated through nuclear factor-κB andERK1/2 signaling pathways as the inhibitors of these pathways could inhibit IL-17-induced COX-2 expression. The conditional medium obtained from the cancer cellscontained prostaglandin E2, the levels of which were increased by IL-17 treatment. When treated with the conditional medium, particularly with the IL-17-induced conditionalmedium, mouse RAW264.7 macrophages and human THP-1 monocytes expressedhigher levels of IL-10 (a marker of M2 macrophages) than inducible nitricoxide synthase or tumor necrosis factor α (markers of M1 macrophages). In contrast,when RAW264.7 and THP-1 cells were treated directly with IL-17, expression of thesemarker genes was not markedly changed. ConclusionThe results of this study suggest that IL-17 indirectly promotes M2 macrophagedifferentiation through stimulation of the COX-2/PGE2 pathway in the cancer cells,thus IL-17 plays an indirect role in regulating the tumor immune microenvironment.

Facile synthesis of AgPt nano-pompons for efficient methanol oxidation: Morphology control and DFT study on stability enhancement

Tao Shao,Dehong Bai,Mingzhu Qiu,Yu Li,Qiankun Zhang,Ziyu Xue,Shijie He,Dongxia Zhang,Xibin Zhou 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.108 No.-

Facile synthesis of more dendritic and uniform Pt-based nanostructures with carbon materials couldgreatly reduce cost and increase Pt utilization for methanol oxidation reaction (MOR) in direct methanolfuel cell (DMFC). This study reports a novel one-pot method to fabricate AgPt nano-pompons (AgPt NPs)with the guidance of N-GQDs through AA reduce the precursor of Ag and Pt. Morphology characterizationdescribes N-GQDs as morphology guiding and dispersing agents to regulate the dendrite formation ofnano-pompons. Under the optimized conditions, the AgPt NPs (Ag1Pt2) display above 11 times improvementin electrocatalytic activity and higher stability for the MOR compared with Pt/C catalysts. Densityfunction theory (DFT) studies prove that the introduction of Ag can greatly enhance the adsorption of COon Pt and promote the transformation of CO to COOH. The facile synthetic method and excellent MORperformance endow AgPt NPs with great application prospect in DMFCs as an anode catalyst.

A Novel Method for Survivability Test Based on End Nodes in Large Scale Network

( Ming Liang ),( Zhao Gang ),( Wang Dongxia ),( Huang Minhuan ),( Li Xiang ),( Miao Qing ),( Xu Fei ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.2

Survivability is a necessary property of network system in disturbed environment. Recovery ability is a key actor of survivability. This paper concludes network survivability into a novel composite metric, i.e. Network Recovery Degree (NRD). In order to measure this metric in quantity, a concept of Source-Destination Pair (SD Pair), is created to abstract end-to-end activity based on end nodes in network, and the quality of SD Pair is also used to describe network performance, such as connectivity, quality of service, link degree, and so on. After that, a Survivability Test method in large scale Network based on SD pairs, called STNSD, is provided. How to select SD Pairs effectively in large scale network is also provided. We set up simulation environment to validate the test method in a severe destroy scenario and evaluate the method scalability in different large scale network scenarios. Experiment and analysis shows that the metric NRD correctly reflects the effort of different survivability strategy, and the proposed test method STNSD has good scalability and can be used to test and evaluate quantitative survivability in large scale network.