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Effect of Heat Sterilization on the Bioactivity of Antibacterial Metabolites Secreted by Xenorhabdus nematophila  [PDF]
Floyd L. Inman,Leonard Holmes
Pakistan Journal of Biological Sciences , 2012,
Abstract: Photorhabdus luminescens and Xenorhabdus nematophila are entomopathogenic bacterial symbionts of beneficial nematodes Heterorhabditis bacteriophora and Steinernema carpocapsae, respectively. These bacterial symbionts are known to secrete an array of toxins, enzymes and antimicrobials that kill, bioconvert and protect the insect host for optimal nematode growth and reproduction. The present study explores heat stability of antibacterial metabolites secreted by X. nematophila. Permeate of a liquid X. nematophila culture was subjected to various sterilization treatments to observe the effects of heat sterilization on antibacterial activity. Activity was measured as bacterial sensitivity which is assayed utilizing a modified-version of the Kirby-Bauer disk diffusion method. Results demonstrate that X. nematophila produces both heat-labile and heat-stabile antibacterials that are effective against different species of bacteria. Results also indicated that heat-stabile components are more active than heat-labile components. The discovery of an environmental organism that produces both heat-stabile and heat-labile antibacterials can be exploited to manufacture these compounds for potential medical applications for human and animal use.
Diversity of Xenorhabdus and Photorhabdus spp. and Their Symbiotic Entomopathogenic Nematodes from Thailand  [PDF]
Aunchalee Thanwisai,Sarunporn Tandhavanant,Natnaree Saiprom,Nick R. Waterfield,Phan Ke Long,Helge B. Bode,Sharon J. Peacock,Narisara Chantratita
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043835
Abstract: Xenorhabdus and Photorhabdus spp. are bacterial symbionts of entomopathogenic nematodes (EPNs). In this study, we isolated and characterized Xenorhabdus and Photorhabdus spp. from across Thailand together with their associated nematode symbionts, and characterized their phylogenetic diversity. EPNs were isolated from soil samples using a Galleria-baiting technique. Bacteria from EPNs were cultured and genotyped based on recA sequence. The nematodes were identified based on sequences of 28S rDNA and internal transcribed spacer regions. A total of 795 soil samples were collected from 159 sites in 13 provinces across Thailand. A total of 126 EPNs isolated from samples taken from 10 provinces were positive for Xenorhabdus (n = 69) or Photorhabdus spp. (n = 57). Phylogenetic analysis separated the 69 Xenorhabdus isolates into 4 groups. Groups 1, 2 and 3 consisting of 52, 13 and 1 isolates related to X. stockiae, and group 4 consisting of 3 isolates related to X. miraniensis. The EPN host for isolates related to X. stockiae was S. websteri, and for X. miraniensis was S. khoisanae. The Photorhabdus species were identified as P. luminescens (n = 56) and P. asymbiotica (n = 1). Phylogenenic analysis divided P. luminescens into five groups. Groups 1 and 2 consisted of 45 and 8 isolates defined as subspecies hainanensis and akhurstii, respectively. One isolate was related to hainanensis and akhurstii, two isolates were related to laumondii, and one isolate was the pathogenic species P. asymbiotica subsp. australis. H. indica was the major EPN host for Photorhabdus. This study reveals the genetic diversity of Xenorhabdus and Photorhabdus spp. and describes new associations between EPNs and their bacterial symbionts in Thailand.
The Entomopathogenic Bacterial Endosymbionts Xenorhabdus and Photorhabdus: Convergent Lifestyles from Divergent Genomes  [PDF]
John M. Chaston, Garret Suen, Sarah L. Tucker, Aaron W. Andersen, Archna Bhasin, Edna Bode, Helge B. Bode, Alexander O. Brachmann, Charles E. Cowles, Kimberly N. Cowles, Creg Darby, Limaris de Léon, Kevin Drace, Zijin Du, Alain Givaudan, Erin E. Herbert Tran, Kelsea A. Jewell, Jennifer J. Knack, Karina C. Krasomil-Osterfeld, Ryan Kukor, Anne Lanois, Phil Latreille, Nancy K. Leimgruber, Carolyn M. Lipke, Renyi Liu, Xiaojun Lu, Eric C. Martens, Pradeep R. Marri, Claudine Médigue, Megan L. Menard, Nancy M. Miller, Nydia Morales-Soto, Stacie Norton, Jean-Claude Ogier, Samantha S. Orchard, Dongjin Park, Youngjin Park, Barbara A. Qurollo, Darby Renneckar Sugar, Gregory R. Richards, Zoé Rouy, Brad Slominski, Kathryn Slominski, Holly Snyder, Brian C. Tjaden, Ransome van der Hoeven, Roy D. Welch, Cathy Wheeler, Bosong Xiang, Brad Barbazuk, Sophie Gaudriault, Brad Goodner, Steven C. Slater, Steven Forst, Barry S. Goldman, Heidi Goodrich-Blair
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027909
Abstract: Members of the genus Xenorhabdus are entomopathogenic bacteria that associate with nematodes. The nematode-bacteria pair infects and kills insects, with both partners contributing to insect pathogenesis and the bacteria providing nutrition to the nematode from available insect-derived nutrients. The nematode provides the bacteria with protection from predators, access to nutrients, and a mechanism of dispersal. Members of the bacterial genus Photorhabdus also associate with nematodes to kill insects, and both genera of bacteria provide similar services to their different nematode hosts through unique physiological and metabolic mechanisms. We posited that these differences would be reflected in their respective genomes. To test this, we sequenced to completion the genomes of Xenorhabdus nematophila ATCC 19061 and Xenorhabdus bovienii SS-2004. As expected, both Xenorhabdus genomes encode many anti-insecticidal compounds, commensurate with their entomopathogenic lifestyle. Despite the similarities in lifestyle between Xenorhabdus and Photorhabdus bacteria, a comparative analysis of the Xenorhabdus, Photorhabdus luminescens, and P. asymbiotica genomes suggests genomic divergence. These findings indicate that evolutionary changes shaped by symbiotic interactions can follow different routes to achieve similar end points.
Entomopathogenic nematode Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), a new member of Slovenian fauna
iga Laznik, Tímea Tóth, Tamás Lakatos, Stanislav Trdan
Acta agriculturae Slovenica , 2008, DOI: 10.2478/v10014-008-0015-4
Abstract: In April 2008, 120 soil samples from 24 locations were collected in Gorenjska, Notranjska and Primorska regions as well as in Ljubljansko barje. The presence of entomopathogenic nematodes was confirmed in 9 samples from 6 locations. Only the sample C101, which was taken in the village Svino in the area of Breginjski kot (western part of Slovenia, the vicinity of Italian border), was sent to genetic analysis. Molecular biological analysis was proved the identity of the sample with the species Steinernema carpocapsae (Weiser). This was the first record of Steinernema carpocapsae in Slovenia. In preceding researches on the fauna of entomopathogenic nematodes in Slovenia, which started in 2007, we already established the occurrence of Steinernema affine (Bovien) and Steinernema feltiae (Filipjev).
Variable fragment of 23S rDNA for classification and identification of Xenorhabdus
以23S rDNA一个多变区作为分子标记对致病杆菌属细菌进行分类鉴定

Zhao Jingxiu,Liu Chunlin,Qiu Lihong,Pang Yi,
Zhao J
,Liu C,Qiu L,Pang Y

微生物学报 , 2012,
Abstract: Objective]Members of Xenorhabdus are symbiotic bacteria of entomopathogenic nematodes Steinernema,and can be applied as biopesticides against insects.Therefore,a rapid and accurate method for classification and identification of Xenorhabdus is essential.Methods] An 845bp-fragment of 23S rDNA sequence of 26 strains of Xenorhabdus representing 20 described species was PCR amplified and sequenced.A phylogenetic tree of Xenorhabdus based on the sequences obtained was constructed and compared to that based on nearly complete 16S rDNA sequences for suitability as molecular maker for classification and identification of Xenorhabdus.Results] The 23S rDNA fragment contained more variable and parsimony-informative sites proportionally,and with greater pairwise distances among sequences compared to those of 16S rDNA.Conclusion] The 23S rDNA fragment can be used to identify Xenorhabdus,especially for a large number of Xenorhabdus strains obtained from field survey.
Entomopathogenic nematode Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) recorded for the first time in Slovenia
iga Laznik, Timea Tóth, Tamás Lakatos, Stanislav Trdan
Acta agriculturae Slovenica , 2008, DOI: 10.2478/v10014-008-0004-7
Abstract: In Slovenia only recently entomopathogenic nematodes were recorded for the first time. In the beginning of 2007, the presence of Steinernema affine was confirmed. During the further investigations in the same year Steinernema feltiae was recorded on the arable field near Cerknica. In the previous year this field was planted with chicory. In Slovenia, until now the entomopathogenic nematodes had a status of an exotic agents and their use was allowed only in the laboratory experiments. We expect that in Slovenia the use of these biological agents against insect pests will become important alternative to insecticides as it is known in many other countries of the world.
Synthesis of szentiamide, a depsipeptide from entomopathogenic Xenorhabdus szentirmaii with activity against Plasmodium falciparum  [cached]
Friederike I. Nollmann,Andrea Dowling,Marcel Kaiser,Klaus Deckmann
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.60
Abstract: The synthesis of the recently characterized depsipeptide szentiamide (1), which is produced by the entomopathogenic bacterium Xenorhabdus szentirmaii, is described. Whereas no biological activity was previously identified for 1, the material derived from the efficient synthesis enabled additional bioactivity tests leading to the identification of a notable activity against insect cells and Plasmodium falciparum, the causative agent of malaria.
Evaluation in vitro of the infection times of engorged females of Rhipicephalus (Boophilus) microplus by the entomopathogenic nematode Steinernema glaseri CCA strain
Carvalho, Leandro Barbiéri de;Furlong, John;Prata, Márcia Cristina de Azevedo;Reis, éder Sebasti?o dos;Batista, Elder Sim?es de Paula;Faza, Aline Pasqualini;Leite, R?mulo Cerqueira;
Ciência Rural , 2010, DOI: 10.1590/S0103-84782010000400030
Abstract: studies have shown that ticks are susceptible to infection by entomopathogenic nematodes. these studies indicate different susceptibilities of ticks to infection by these fungi, depending on the tick species, development phase, entomopathogenic nematodes species and strains and the time the ticks are exposed to them. usually this period ranges from 24 to 72 hours. the aim of this study was to evaluate the infection times in vitro of engorged rhipicephalus (boophilus) microplus females by the entomopathogenic nematodes steinernema glaseri cca strain, by analysis of the ticks' biological parameters. the results show that a 2-hour exposure time was sufficient for the engorged r. microplus females to be infected by s. glaseri cca, but that a minimum exposure time of 24 hours was necessary to generate treatment efficacy above 90%.
Analysis of biological parameters of Boophilus microplus Canestrini, 1887 exposed to entomopathogenic nematodes Steinernema carpocapsae Santa Rosa and All strains (Steinernema: Rhabditida)
Freitas-Ribeiro, Gláucia Marques;Furlong, John;Vasconcelos, Viviane Oliveira;Dolinski, Cláudia;Loures-Ribeiro, Alan;
Brazilian Archives of Biology and Technology , 2005, DOI: 10.1590/S1516-89132005000800007
Abstract: engorged and partially engorged females of boophilus microplus were exposed to 600; 3,000; 6,000 and 30,000 infective juveniles of steinernema carpocapsae weiser, 1955 santa rosa and all strains per dish, under lab conditions. eggs weight, pre-laying period, laying period, survival period, reproductive efficiency rate, percentage of larval eclosion and lethal concentrations of 50% and 90% (cl50 and cl90) were calculated for engorged females. in the case of partially engorged females, only egg weight, survival period and cl50 and cl90 were calculated. all biological parameters of engorged or partially engorged females were altered by exposition of s. carpocapsae infective juveniles (ijs), santa rosa and all strains (p<0.05). the increase in the response was directly proportional to the increase of ijs concentration per petri dish (p<0.05). results suggested that entomopathogenic nematodes could have a positive role in the control of cattle tick.
Yuliantoro Baliadi,Ika Rocdjatun Sastrahidayat,Syamsudin Djauhari,Bambang Tri Rahardjo
Agrivita : Journal of Agricultural Science , 2011,
Abstract: The pathogenicity, development and reproduction of Steinernema sp., isolate Skpr-20/Str, were studied using Tenebrio molitor. Results revealed that pathogenicity, development and reproduction were significantly influenced by nematode doses. Although the number of invading IJs increased with increasing dose, percentage penetration declined. The IJs reached adulthood within 3 days. Females laid eggs from day 4-7. All eggs remaining inside uterus develop inside the maternal body. The first female bearing endotokia matricida was observed on day 5. In a sand-based assay, nematode was more pathogenic at lower dose instead of higher ones, where optimum dose was 80 nematodes per larva and average number of progeny per female was 5438. Under crowded conditions, development proceeds to IJ stage instead of the J3. The average length and width decreased with increasing of nematode doses. The IJ produced in cadavers infested with 640 nematodes per larva was significantly smaller (492 ± 6.4 μm) than offspring from other doses. The number of days which nematodes first emerged from the cadavers decreased with increasing dose. IJ first emerged at the average of 10-13 days at high IJ densities. It is concluded that the wide experimental characteristic of EPNs is also true for Steinernema sp., isolate Skpr-20/Str.
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