ABSTRACT
The antifungal properties and mechanism of three types of chitosan against the rice sheath blight pathogen, Rhizoctonia solani, were evaluated. Each chitosan had strong antifungal activity against R. solani and protected rice seedlings from sheath blight, in particular, two types of acid-soluble chitosan caused a 60-91 % inhibition in mycelial growth, 31-84 % inhibition of disease incidence, and 66-91 % inhibition in lesion length. The mechanism of chitosan in protection of rice from R. solani pathogen was attributed to direct destruction of the mycelium, evidenced by scanning and transmission electron microscopic observations and pathogenicity testing; indirect induced resistance was evidenced by the changes in the activities of the defense-related phenylalanine ammonia lyase, peroxidase and polyphenol oxidase in rice seedling. To our knowledge, this is the first report on the antifungal activity of chitosan against rice R. solani.
Subject(s)
Antifungal Agents/pharmacology , Chitosan/pharmacology , Rhizoctonia/drug effects , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Mycelium/drug effects , Mycelium/ultrastructure , Oryza/microbiology , Plant Diseases/microbiology , Rhizoctonia/isolation & purification , Rhizoctonia/ultrastructureABSTRACT
Infections by Enterobacter species are common and are multidrug resistant. The use of bactericidal surface materials such as copper has lately gained attention as an effective antimicrobial agent due to its deadly effects on bacteria, yeast, and viruses. The aim of the current study was to assess the antibacterial activity of copper surfaces against Enterobacter species. The antibacterial activity of copper surfaces was tested by overlying 5×10(6) CFU/ml suspensions of representative Enterobacter strains and comparing bacterial survival counts on copper surfaces at room temperature. Iron, stainless steel, and polyvinylchloride (PVC) were used as controls. The mechanisms responsible for bacterial killing on copper surfaces were investigated by a mutagenicity assay of the D-cycloserin (cyclA gene), single cell gel electrophoresis, a staining technique, and inductively coupled plasma mass spectroscopy. Copper yielded a significant decrease in the viable bacterial counts at 2 h exposure and a highly significant decrease at 4 h. Loss of cell integrity and a significantly higher influx of copper into bacterial cells exposed to copper surfaces, as compared to those exposed to the controls, were documented. There was no increase in mutation rate and DNA damage indicating that copper contributes to bacterial killing by adversely affecting cellular structure without directly targeting the genomic DNA. These findings suggest that copper's antibacterial activity against Enterobacter species could be utilized in health care facilities and in food processing plants to reduce the bioburden, which would increase protection for susceptible members of the community.
Subject(s)
Anti-Infective Agents/pharmacology , Copper/pharmacology , Drug Resistance, Multiple, Bacterial/drug effects , Enterobacter/drug effects , Colony Count, Microbial , Cycloserine/toxicity , Electrophoresis , Mass Spectrometry , Microbial Viability/drug effects , Staining and Labeling , Temperature , Time FactorsABSTRACT
Stenotrophomonas maltophilia is an endophyte which plays important roles in agricultural production as a plant growth-promoting bacterium. Here, we present the draft genome sequence of strain RR-10, which was isolated from a rice root in a rice field of China.
Subject(s)
DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Genome, Bacterial , Oryza/microbiology , Plant Roots/microbiology , Stenotrophomonas maltophilia/genetics , Stenotrophomonas maltophilia/isolation & purification , China , Endophytes/genetics , Endophytes/isolation & purification , Molecular Sequence Data , Sequence Analysis, DNAABSTRACT
Acidovorax avenae subsp. avenae is a phytobacterium which is the causative agent of several plant diseases with economic significance. Here, we present the draft genome sequence of strain RS-1, which was isolated from rice shoots in a rice field in China. This strain can cause bacterial stripe of rice.
Subject(s)
Comamonadaceae/genetics , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Genome, Bacterial , Sequence Analysis, DNA , China , Comamonadaceae/isolation & purification , Comamonadaceae/metabolism , Molecular Sequence Data , Oryza/microbiology , Plant Diseases/microbiology , Plant Shoots/microbiologyABSTRACT
Enterobacter mori is a plant-pathogenic enterobacterium responsible for the bacterial wilt of Morus alba L. Here we present the draft genome sequence of the type strain, LMG 25706. To the best of our knowledge, this is the first genome sequence of a plant-pathogenic bacterium in the genus Enterobacter.
Subject(s)
Enterobacter/genetics , Genome, Bacterial , Morus/microbiology , Plant Diseases/microbiology , Base Sequence , Enterobacter/classification , Enterobacter/isolation & purification , Molecular Sequence Data , Sequence Analysis, DNAABSTRACT
Thirty-six pathogenetic bacterial strains were isolated from wilted mulberry plants in Hangzhou, Zhejiang province of China. The six representative strains were confirmed to be involved in more than one Enterobacter species by common bacteriological test, electron microscope observation, hypersensitive reaction, Koch's postulates, physiological and biochemical test, biology, fatty acid methyl esters analysis (FAMEs), enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR), 16s rRNA sequences analysis, and comparative analysis with 7 type strains and 3 reference strains. This is the first report on mulberry disease caused by Enterobacter spp. in the world providing new evidence on induction of the plant disease in this genus. The results are not only important in the mulberry disease management but also have significant scientific value for further studies of opportunistic human pathogens and environmental strains in Enterobacter.
