Stability and Activities of Antibiotics Produced during Infection of the Insect
            <i>Galleria mellonella</i>
            by Two Isolates of
            <i>Xenorhabdus nematophilus</i>

Maxwell, Philip W.; Chen, Genhui; Webster, John; Dunphy, Gary B.

doi:10.1128/aem.60.2.715-721.1994

Cited by 89 publications

(34 citation statements)

References 21 publications

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“…In this context, the formulation of both tryptone soya broth and BYP broth include complex organic nitrogen sources and sodium chloride. Our data also verified the previous reports by Maxwell et al [19] and Ji et al [20] regarding the high productivity of fermentation media that contain complex organic nitrogen sources. Chen [21] suggested that the use of different media may change the levels of the expressed antibiotic activity.…”

Section: Effect Of Growth Mediumsupporting

confidence: 93%

Enhanced production of di-(2-ethylhexyl) phthalate (DEHP) by Bacillus subtilis AD35 using response surface methodology (RSM)

Lotfy

Hassan

El-Aal

et al. 2019

Biotechnology & Biotechnological Equipment

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Our previous study demonstrated that a new Bacillus subtilis AD35 was the first Bacillus sp. so far possessing the capability to produce the antibacterial compound di-(2-ethylhexyl) phthalate (DEHP) [Lotfy WA, Mostafa SW, Adel AA, et al. Production of DEHP by Bacillus subtilis AD35: isolation, purification, characterization and biological activities. Microb Pathog. 2018;124:89-100]. In this study, we investigate the process parameters influencing DEHP production by B. subtilis AD35. The best culture medium, carbon and nitrogen source that significantly affected DEHP synthesis were beef-yeast-peptone medium, starch and L-asparagine, respectively. A fractional factorial design (FFD) was applied to screen the fermentation conditions affecting DEHP formation. Agitation rate, inoculum size and sodium chloride concentration were found to be the major factors affecting the synthesis of DEHP. Sequentially, response surface methodology (RSM) was implemented and a polynomial model was developed to predict maximum DEHP activities against Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), Salmonella typhimurium, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Pseudomonas aeruginosa and Aeromonas hydrophila. At optimized conditions, agitation rate, 220 rpm; inoculum size, 0.075% (v/v) and sodium chloride concentration, 0.75% (w/v), DEHP activity markedly increased to 24.7 AU, which represents an approximately 707% increase when compared to the pre-optimized conditions. The work reported here represents the first optimization of the process parameters influencing DEHP synthesis by B. subtilis AD35. ARTICLE HISTORY

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Section: Effect Of Growth Mediumsupporting

confidence: 93%

Enhanced production of di-(2-ethylhexyl) phthalate (DEHP) by Bacillus subtilis AD35 using response surface methodology (RSM)

Lotfy

Hassan

El-Aal

et al. 2019

Biotechnology & Biotechnological Equipment

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“…Xcn1 and Xcn2 ( Fig. 1A) are major antibiotics produced by X. nematophila in broth culture (McInerney et al, 1991) and in insects (Maxwell et al, 1994). The NRPS gene, xcnA, previously designated nrps1, was shown to be highly expressed in an ompR strain that displayed a high level of antibiotic activity (Park and Forst, 2006).…”

Section: Identification Of Genes Involved In Xenocoumacin Productionmentioning

confidence: 98%

Genetic analysis of xenocoumacin antibiotic production in the mutualistic bacterium Xenorhabdus nematophila

Park

Ciezki

Hoeven

et al. 2009

Molecular Microbiology

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SummaryXenocoumacin 1 (Xcn1) and xenocoumacin 2 (Xcn2) are the major antimicrobial compounds produced by Xenorhabdus nematophila. To study the role of Xcn1 and Xcn2 in the life cycle of X. nematophila the 14 gene cluster (xcnA-N) required for their synthesis was identified. Overlap RT-PCR analysis identified six major xcn transcripts. Individual inactivation of the non-ribosomal peptide synthetase genes, xcnA and xcnK, and polyketide synthetase genes, xcnF, xcnH and xcnL, eliminated Xcn1 production. Xcn1 levels and expression of xcnA-L were increased in an ompR strain while Xcn2 levels and xcnMN expression were reduced. Xcn1 production was also increased in a strain lacking acetyl-phosphate that can donate phosphate groups to OmpR. Together these findings suggest that OmpR-phosphate negatively regulates xcnA-L gene expression while positively regulating xcnMN expression. HPLC-MS analysis revealed that Xcn1 was produced first and was subsequently converted to Xcn2. Inactivation of xcnM and xcnN eliminated conversion of Xcn1 to Xcn2 resulting in elevated Xcn1 production. The viability of the xcnM strain was reduced 20-fold relative to the wild-type strain supporting the idea that conversion of Xcn1 to Xcn2 provides a mechanism to avoid self-toxicity. Interestingly, inactivation of ompR enhanced cell viability during prolonged culturing.

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“…Mutants were analysed for motility as described by Vivas and Goodrich-Blair (2001). Plate assays were performed to observe protease activity (Boemare et al, 1997), lipase activity (Sierra, 1956) and antibiotic activity (Maxwell et al, 1994;Vivas and Goodrich-Blair, 2001). Haemolytic activity was assayed using blood agar plates (Rowe and Welch, 1994) with 5% defibrinated sheep blood (Colorado Serum).…”

Section: Phenotypic Assays For Colonization Mutantsmentioning

confidence: 99%

Identification of Xenorhabdus nematophila genes required for mutualistic colonization of Steinernema carpocapsae nematodes

Heungens¹,

Cowles

Goodrich‐Blair³

2002

Molecular Microbiology

184

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SummaryOne stage in the symbiotic interaction between the bacterium Xenorhabdus nematophila and its nematode host, Steinernema carpocapsae , involves the species-specific colonization of the nematode intestinal vesicle by the bacterium. To characterize the bacterial molecular determinants that are essential for vesicle colonization, we adapted and applied a signature-tagged mutagenesis (STM) screen to this system. We identified 15 out of 3000 transposon mutants of X. nematophila with at least a 15-fold reduction in average vesicle colonization. These 15 mutants harbour disruptions in nine separate loci. Three of these loci have predicted open reading frames (ORFs) with similarity to genes ( rpoS , rpoE , lrp ) encoding regulatory proteins; two have predicted ORFs with similarity to genes ( aroA , serC ) encoding amino acid biosynthetic enzymes; one, designated nilB (nematode intestine localization), has an ORF with similarity to a gene encoding a putative outer membrane protein (OmpU) in Neisseria ; and three, nilA , nilC and nilD , have no apparent homologues in the public database. nilA , nilB and nilC are linked on a single 4 kb locus. nilB and nilC are > 10 4 -fold reduced in their ability to colonize the nematode vesicle and are predicted to encode membrane-localized proteins. The nilD locus contains an extensive repeat region and several small putative ORFs. Other than reduced colonization, the nilB , nilC and nilD mutants did not display alterations in any other phenotype tested, suggesting a specific role for these genes in allowing X. nematophila to associate with the nematode host.

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Stability and Activities of Antibiotics Produced during Infection of the Insect Galleria mellonella by Two Isolates of Xenorhabdus nematophilus

Cited by 89 publications

References 21 publications

Enhanced production of di-(2-ethylhexyl) phthalate (DEHP) by Bacillus subtilis AD35 using response surface methodology (RSM)

Enhanced production of di-(2-ethylhexyl) phthalate (DEHP) by Bacillus subtilis AD35 using response surface methodology (RSM)

Genetic analysis of xenocoumacin antibiotic production in the mutualistic bacterium Xenorhabdus nematophila

Identification of Xenorhabdus nematophila genes required for mutualistic colonization of Steinernema carpocapsae nematodes

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