Exserohilum rostratum: characterization of a cross-kingdom pathogen of plants and humans.

Pathogen host shifts represent a major source of new infectious diseases. There are several examples of cross-genus host jumps that have caused catastrophic epidemics in animal and plant species worldwide. Cross-kingdom jumps are rare, and are often associated with nosocomial infections. Here we provide an example of human-mediated cross-kingdom jumping of Exserohilum rostratum isolated from a patient who had received a corticosteroid injection and died of fungal meningitis in a Florida hospital in 2012. The clinical isolate of E. rostratum was compared with two plant pathogenic isolates of E. rostratum and an isolate of the closely related genus Bipolaris in terms of morphology, phylogeny, and pathogenicity on one C3 grass, Gulf annual rye grass (Lolium multiflorum), and two C4 grasses, Japanese stilt grass (Microstegium vimineum) and bahia grass (Paspalum notatum). Colony growth and color, as well as conidia shape and size were the same for the clinical and plant isolates of E. rostratum, while these characteristics differed slightly for the Bipolaris sp. isolate. The plant pathogenic and clinical isolates of E. rostratum were indistinguishable based on morphology and ITS and 28S rDNA sequence analysis. The clinical isolate was as pathogenic to all grass species tested as the plant pathogenic strains that were originally isolated from plant hosts. The clinical isolate induced more severe symptoms on stilt grass than on rye grass, while this was the reverse for the plant isolates of E. rostratum. The phylogenetic similarity between the clinical and plant-associated E. rostratum isolates and the ability of the clinical isolate to infect plants suggests that a plant pathogenic strain of E. rostratum contaminated the corticosteroid injection fluid and was able to cause systemic disease in the affected patient. This is the first proof that a clinical isolate of E. rostratum is also an effective plant pathogen.

Synthesis, antimicrobial evaluation, and structure-activity relationship of α-pinene derivatives.

Several (+)- and (-)-α-pinene derivatives were synthesized and evaluated for their antimicrobial activity toward Gram-positive bacteria Micrococcus luteus and Staphylococcus aureus, Gram-negative bacterium Escherichia coli, and the unicellular fungus Candida albicans using bioautographic assays. (+)-α-Pinene 1a showed modest activity against the test organisms, whereas (-)-α-pinene 1b showed no activity at the tested concentration. Of all the α-pinene derivatives evaluated, the ß-lactam derivatives (10a and 10b) were the most antimicrobial. The increase in the antimicrobial activity of 10a compared to 1a ranged from nearly 3.5-fold (C. albicans) to 43-fold (S. aureus). The mean ± standard deviation for the zone of inhibition (mm) for 10a (C. albicans) was 31.9 ± 4.3 and that for S. aureus was 51.1 ± 2.9. Although (-)-α-pinene 1b was not active toward the test microorganisms, the corresponding ß-lactam 10b, amino ester 13b, and amino alcohol 14b showed antimicrobial activity toward the test microorganisms. The increase in the antimicrobial activity of 10b compared to 1b ranged from 32-fold (S. aureus) to 73-fold (M. luteus). The mean ± standard deviation for the zone of inhibition (mm) for 10b (S. aureus) was 32.0 ± 0.60 and that for M. luteus was 73.2 ± 0.30.

Complete genome sequence of Paenibacillus sp. strain JDR-2.

Paenibacillus sp. strain JDR-2, an aggressively xylanolytic bacterium isolated from sweetgum (Liquidambar styraciflua) wood, is able to efficiently depolymerize, assimilate and metabolize 4-O-methylglucuronoxylan, the predominant structural component of hardwood hemicelluloses. A basis for this capability was first supported by the identification of genes and characterization of encoded enzymes and has been further defined by the sequencing and annotation of the complete genome, which we describe. In addition to genes implicated in the utilization of ß-1,4-xylan, genes have also been identified for the utilization of other hemicellulosic polysaccharides. The genome of Paenibacillus sp. JDR-2 contains 7,184,930 bp in a single replicon with 6,288 protein-coding and 122 RNA genes. Uniquely prominent are 874 genes encoding proteins involved in carbohydrate transport and metabolism. The prevalence and organization of these genes support a metabolic potential for bioprocessing of hemicellulose fractions derived from lignocellulosic resources.

Mutation in Caenorhabditis elegans Krüppel-like factor, KLF-3 results in fat accumulation and alters fatty acid composition.

In vertebrates, adipose tissue stores energy in the form of fat. Fat storage is tightly controlled by and dynamically balanced with energy expenditure under physiological settings; the perturbation of fat in either excess (obese) or deficit (lipodystrophy) has devastating pathologic consequences in the fueling of homeostasis and organismal fitness. The process by which fat storage is coordinated through positive and negative feedback signals is still poorly understood. To address potential mechanisms underlying fat storage we study a Caenorhabditis elegans Krüppel-like transcription factor, Ce-klf-3 and demonstrate that klf-3 is a hitherto unrecognized key regulator of fat metabolism in C. elegans. The Ce-klf-3 is highly expressed during larval development and predominantly present in intestine: the site of fat digestion, absorption, storage, and utilization. We found a strong positive correlation between klf-3 expression and fat deposition in a worm's intestine. Significantly, a klf-3 (ok1975) loss-of-function mutation, characterized by the deletion of a 1658-bp sequence spanning the 3' end of exon 2 through to the 5' end of exon 3 of klf-3, enhanced fat deposition in the intestine and caused severe defects in worm reproduction. Although klf-3 mutants seemed very similar to wild type worms in appearance and life span, 70% of mutants became semi-sterile, each producing 40-50 viable progenies, and the remaining 30% were rendered completely sterile toward adulthood. Notably, both mutant types displayed extensive deposition of fat in the intestine. Our study also demonstrates that klf-3 is critical for maintaining normal fatty acid composition by regulating genes involved in a fatty acid desaturation pathway. Strikingly, klf-3 mutant animals with impaired fatty acid beta-oxidation pathway genes resulted in fat accumulation in the mutant worm. We present the first clear in vivo evidence supporting essential regulatory roles of KLF-3 in fat storage in C. elegans and shed light on the human equivalent in disease-gene association.

Reclassification of subspecies of Acidovorax avenae as A. Avenae (Manns 1905) emend., A. cattleyae (Pavarino, 1911) comb. nov., A. citrulli Schaad et al., 1978) comb. nov., and proposal of A. oryzae sp. nov.

The bacterium Acidovorax avenae causes disease in a wide range of economically important monocotyledonous and dicotyledonous plants, including corn, rice, watermelon, anthurium, and orchids. Genotypic and phenotypic relatedness among strains of phytopathogenic A. avenae subsp. avenae, A. avenae subsp. citrulli, A. avenae subsp. cattleyae and A. konjaci, as well as all other Acidovorax species, including A. facilis, the type strain of Acidovorax, was determined. The 16s rDNA sequencing confirmed previous studies showing the environmental species to be very distant from the phytopathogenic species. DNA/DNA reassociation assays on the different strains of A. avenae revealed four (A, B, C, and D) distinct genotypes. Taxon A included six A. avenae subsp. avenae strains from corn that had a mean reciprocal similarity of 81%; taxon B included six A. avenae subsp. avenae strains from rice that had a mean reciprocal similarity of 97%; taxon C contained 11 A. avenae subsp. citrulli strains from cucurbits (cantaloupe, watermelon, and pumpkin) that had a mean reciprocal similarity of 88%, and taxon D contained four A. avenae subsp. cattleyae strains from orchids that had a mean similarity of 98%. The mean reciprocal relatedness between taxa A, B, C, and D was less than 70%. Sequence analysis of 16S rDNA and the 16S-23S rDNA internally transcribed spacer region, as well as AFLP analysis, revealed the same four taxa. All four were easily differentiated phenotypically from each other and from all other recognized Acidovorax species. Strains of A. avenae did not contain 3-hydroxyoctanoic acid, which was found in all other species. On the basis of these and previous genetic and phenotypic results, we propose an emendation of the species A. avenae. A. avenae subsp. citrulli (C strains) and A. avenae subsp. cattleyae (D strains) should be elevated to species rank as A. citrulli and A. cattleyae, respectively. We further propose a new taxon for the B strains, A. oryzae sp. nov. with FC-143T = ICPB 30003T = ICMP 3960T = ATCC 19882T as the type strain.

A Leaf Spot and Blight of Greenhouse Tomato Seedlings Incited by a Herbaspirillum sp.

A leaf spot and blighting were observed on leaves of tomato transplants from a producer in Florida in 2001 and 2002. A nonfluorescent bacterium was isolated consistently from affected tissue. The typical bacterium was a gram negative, strictly aerobic, slightly curved rod with one or two flagella. Sequence analysis of the 16S rRNA indicated that two representative strains, F1 and SE1, had greater than 99% nucleotide sequence identity with Herbaspirillum huttiense and H. rubrisubalbicans. The cellular fatty acid composition of the total of 16 tomato strains was very similar to H. huttiense and H. rubrisubalbicans. Based on carbon utilization, six of nine strains tested with the Biolog system were identified as Herbaspirillum spp. The tomato strains were oxidase positive and grew at 40°C, but were negative for levan production, pectate hydrolysis, and arginine dihydrolase activity. Based upon this polyphasic analysis, we concluded that the strains were most closely related to H. huttiense, although placement in this species would require further analyses. However, the tomato strains and H. rubrisubalbicans, but not H. huttiense, caused confluent necrosis when infiltrated at high concentrations into tomato leaves and were able to produce leaf spot symptoms on inoculated tomato seedlings in the greenhouse. Using pulsed-field gel electrophoresis, we determined that there was considerable variability between the strains collected in 2001 and 2002.