Biocontrol science最新文献

This study was to survey the capturing rate in Japanese dental clinics of the Lasioderma serricorne (cigarette beetles) , and to evaluate the beetle's potential as a carrier for transmission of nosocomial pathogens. L. serricorne imagoes were captured in pheromone traps in 14 Japanese dental clinics in August and September 2012 and 2013, and their numbers recorded. Polymerase chain reaction (PCR) for the bacterial antibiotic-resistant genes mecA, vanA, vanB, blaIMP, and blaVIM was performed on the captured L. serricorne imagoes. Bacterial species in the captured specimens were identified by 16S rRNA PCR and sequencing analysis. The L. serricorne imagoes were captured from 10 dental clinics (71.4%) . We failed to detect the presence of nosocomial antibiotic-resistant pathogens in L. serricorne imagoes. The bacterial species detected most commonly in the imagoes was Wolbachia sp., an intracellular proteobacterium infecting certain insect species. Monitoring of insects including L. serricorne should be incorporated into regiment of the infection control.

Fumigation has been the most convenient method in the field of pest control in museums. In this study, as fumigants, ethanol 70%, deltamethrin (commercial pesticide (CP) ) , essential oil (EO) from Pinus regida, and low oxygen microenvironment (0.1%, (LOM) ) were tested individually and jointly against museum fungal strain Alternaria alternata. Three concentrations of each CP and EO were chosen for evaluating the individual effect. In the joint action fumigation process, three lower concentrations of CP and EO were tested in LOM. The rate of mycelial growth inhibition at each fumigation process was determined by two steps: 1) directly after the fumigation process and 2) after 7 d of the inoculation of the fumigated spores in new medium and incubating it in normal condition. The results demonstrated that applying of each chemical (CP or EO) in LOM enhanced its fungicidal activity and that effect of EO improved from fungistatic to fungicidal by jointing with LOM.

We analyzed the contamination of environmental water samples with Legionella spp. using a conventional culture method, real-time quantitative PCR (qPCR), and real-time qPCR combined with an amoebic co-culture method. Samples (n = 110) were collected from 19 cooling towers, 31 amenity water facilities, and 60 river water sources of tap water in Japan. Legionella was detected in only three samples (3/110, 2.7%) using the culture method. The rate of Legionella detection using amoebic co-culture followed by qPCR was 74.5%, while that using qPCR without amoebic co-culture was 75.5%. A higher than 10-fold bacterial count was observed in 19 samples (19/110, 17.3%) using real-time qPCR subsequent to amoebic co-culture, compared with identical samples analyzed without co-culture. Of these 19 samples, 13 were identified as Legionella spp., including L. pneumophila and L. anisa, and the non-culturable species were identified as L. lytica and L. rowbothamii. This study showed that the detection of Legionella spp., even in those samples where they were not detected by the culture method, was possible using real-time qPCR and an amoebic co-culture method. In addition, this analytical test combination is a useful tool to detect viable and virulent Legionella spp..

Striped catfish (Pangasianodon hypophthalmus) farming in the Mekong Delta Vietnam (MKDVN) importantly contributes to national aquaculture export. Currently, however, diseases occur more frequently across the entire MKDVN region. One of the most common types is hemorrhagic septicemia caused by Aeromonas hydrophila. In this study, isolation and selection of the phages for control in vitro Aeromonas hydrophila were conducted. 24 phages were isolated from 100 striped catfish pond water samples. Next, lytic activity of these phages was clarified. Four phages with short latent period (about 25 to 40 min) and/or high burst size (about 67 to 94 PFU/ cell) were selected to evaluate their infection activity to different phage-resistant A. hydrophila strains. Two phages termed as TG25P and CT45P were subjected to the phage cocktail to inactivate A. hydrophila. Re-growth of the host bacteria appeared about eight hours after treatment. Usage of the phage cocktail that attach different host bacterial receptors is not always much effective than usage of single phage. This is the first report about phage therapy to control A. hydrophila isolated from striped catfish. Some challenges in the phage cocktail were shown to achieve strategies in prospective studies in the context of high antibiotic resistance of A. hydrophila.

　Legionella spp. exist naturally in association with amoeba in water environments and are known to be the etiological agent of a severe form of pneumonia. To detect diverse Legionella populations in cooling tower water systems, amoebic coculturing was performed for 15 water samples obtained from five different kinds of facilities in six geographically different locations. The growth of Legionella in coculture with Acanthamoeba sp. cells was monitored by quantitative PCR targeting Legionella-specific 16S rRNA genes. Seven out of the 15 samples were positive for Legionella growth and subjected to clone library analysis. A total of 333 clones were classified into 14 operational taxonomic units composed of seven known species and seven previously undescribed groups. Four of the seven Legionella-growth-positive samples harbored detectable levels of free-living amoeba and were predominated by either L. drozanskii or L. lytica, by both L. bozemanii and L. longbeachae, or by a not-yet-described group named OTU 4. The Legionella-growth- positive samples contained higher ATP levels (>980 pM) than the growth-negative samples (<160 pM) , suggesting that ATP content would be a good indicator of the presence of viable but nonculturable Legionella populations able to grow with amoeba.

Role of Trichoderma species is well documented as antagonists as well as plant growth enhancers. Presently, the fungicidal potential of three Trichoderma species namely, T. koningii (FCBP769) , T. viride (FCBP904) , and T. harzianum (FCBP1277) was assessed against Alternaria alternata that causes leaf necrotic spots of Syzygium cumini and broad range of other plants using 0, 15, 30, 45, 60 and 75% dilutions of filtrates. There was a significant reduction of around 40-95%, 22-86% and 52-91% in fungal biomass by T. koningii, T. viride and T. harzianum, respectively. In fractionation bioassays, Trichoderma metabolites were partitioned using organic solvents viz., n-butanol, n-hexane, chloroform and ethyl acetate. Antifungal activity at different concentrations (10, 20, 30, 40 and 50 ppm) was assessed against the pathogen. Ethyl acetate fraction of T. koningii extract displayed the most promising activity resulting in 10-90% suppression in biomass. In case of T. viride butanol fraction proved the most effective in retarding the growth of pathogen from 20 to 80%. While T. harzianum extract revealed 55-85% arrest in fungal biomass due to n-hexane fraction. Present study concludes that test Trichoderma species demonstrated a strong fungicidal activity against A. alternata. Current research offers the possibility of developing strategies for controlling pathogens with bioactive metabolites of Trichoderma.