Characterization of three Francisella tularensis genomes from Oklahoma, USA.

Francisella tularensis , the causative agent for tularaemia, is a Tier 1 select agent, and a pan-species pathogen of global significance due to its zoonotic potential. Consistent genome characterization of the pathogen is essential to identify novel genes, virulence factors, antimicrobial resistance genes, for studying phylogenetics and other features of interest. This study was conducted to understand the genetic variations among genomes of F. tularensis isolated from two felines and one human source. Pan-genome analysis revealed that 97.7 % of genes were part of the core genome. All three F. tularensis isolates were assigned to sequence type A based on single nucleotide polymorphisms (SNPs) in sdhA. Most of the virulence genes were part of the core genome. An antibiotic resistance gene coding for class A beta-lactamase was detected in all three isolates. Phylogenetic analysis showed that these isolates clustered with other isolates reported from Central and South-Central USA. Assessment of large sets of the F. tularensis genome sequences is essential in understanding pathogen dynamics, geographical distribution and potential zoonotic implications.

Whole-Genome Sequence of Multidrug-Resistant Bibersteinia trehalosi Strain OADDL-BT1.

The genome of a multidrug-resistant strain of Bibersteinia trehalosi isolated from a calf with chronic pneumonia is presented. The draft genome sequences have been deposited at DDBJ/ENA/GenBank.

The Genome of a Thermo Tolerant, Pathogenic Albino Aspergillus fumigatus.

Biotechnologists are interested in thermo tolerant fungi to manufacture enzymes active and stable at high temperatures, because they provide improved catalytic efficiency, strengthen enzyme substrate interactions, accelerate substrate enzyme conversion rates, enhance mass transfer, lower substrate viscosity, lessen contamination risk and offer the potential for enzyme recycling. Members of the genus Aspergillus live a wide variety of lifestyles, some embrace GRAS status routinely employed in food processing while others such as Aspergillus fumigatus are human pathogens. A. fumigatus produces melanins, pyomelanin protects the fungus against reactive oxygen species and DHN melanin produced by the pksP gene cluster confers the gray-greenish color. pksP mutants are attenuated in virulence. Here we report on the genomic DNA sequence of a thermo tolerant albino Aspergillus isolated from rain forest composted floors. Unexpectedly, the nucleotide sequence was 95.7% identical to the reported by Aspergillus fumigatus Af293. Genome size and predicted gene models were also highly similar, however differences in DNA content and conservation were observed. The albino strain, classified as Aspergillus fumigatus var. niveus, had 160 gene models not present in A. fumigatus Af293 and A. fumigatus Af293 had 647 not found in the albino strain. Furthermore, the major pigment generating gene cluster pksP appeared to have undergone genomic rearrangements and a key tyrosinase present in many aspergilli was missing from the genome. Remarkably however, despite the lack of pigmentation A. fumigatus var. niveus killed neutropenic mice and survived macrophage engulfment at similar rates as A. fumigatus Af293.

Proteomic and bioinformatic analyses of putative Mannheimia haemolytica secretome by liquid chromatography and tandem mass spectrometry.

Mannheimia haemolytica is a major bacterial contributor to bovine respiratory disease complex that costs the livestock industry a billion dollars a year in USA. Commercial vaccines are only partially efficacious under field conditions. Earlier studies found that outer membrane protein preparations and culture supernatants can induce immune responses that enhance resistance to challenge by M. haemolytica strains. The objective of this study was to characterize secretome of two M. haemolytica stains grown under two different media. Bacteria-free concentrated supernatants from M. haemolytica culture was subjected to LC-MS/MS. The secretome of M. haemolytica from both strains yielded 923 proteins. Using bioinformatic tools, 283 were identified as secreted proteins. Further breakdown of 283 proteins showed that 114 (40.2%), 184 (65.0%), 138(48.7%), 151 (53.3%) and 172 (60.7%) were characterized as secreted proteins by SignalP 4.1, SecretomeP 2.0, LipoP, Phobius, and PRED-TAT, respectively. A total of 95 (33.56%) proteins were characterized as being secreted via non-classical pathway as opposed to the majority that were secreted in signal peptide dependent pathway. The demonstrated proteins include all previously immunologically characterized M. haemolytica proteins. The potential of using secretome analysis in the design and development of a multivalent vaccine is discussed.

Myceliophthora thermophila M77 utilizes hydrolytic and oxidative mechanisms to deconstruct biomass.

Biomass is abundant, renewable and useful for biofuel production as well as chemical priming for plastics and composites. Deconstruction of biomass by enzymes is perceived as recalcitrant while an inclusive breakdown mechanism remains to be discovered. Fungi such as Myceliophthora thermophila M77 appear to decompose natural biomass sources quite well. This work reports on this fungus fermentation property while producing cellulolytic enzymes using natural biomass substrates. Little hydrolytic activity was detected, insufficient to explain the large amount of biomass depleted in the process. Furthermore, this work makes a comprehensive account of extracellular proteins and describes how secretomes redirect their qualitative protein content based on the nature and chemistry of the nutritional source. Fungus grown on purified cellulose or on natural biomass produced secretomes constituted by: cellobiohydrolases, cellobiose dehydrogenase, ß-1,3 glucanase, ß-glucosidases, aldose epimerase, glyoxal oxidase, GH74 xyloglucanase, galactosidase, aldolactonase and polysaccharide monooxygenases. Fungus grown on a mixture of purified hemicellulose fractions (xylans, arabinans and arabinoxylans) produced many enzymes, some of which are listed here: xylosidase, mixed ß-1,3(4) glucanase, ß-1,3 glucanases, ß-glucosidases, ß-mannosidase, ß-glucosidases, galactosidase, chitinases, polysaccharide lyase, endo ß-1,6 galactanase and aldose epimerase. Secretomes produced on natural biomass displayed a comprehensive set of enzymes involved in hydrolysis and oxidation of cellulose, hemicellulose-pectin and lignin. The participation of oxidation reactions coupled to lignin decomposition in the breakdown of natural biomass may explain the discrepancy observed for cellulose decomposition in relation to natural biomass fermentation experiments.