Pan-Genome Portrait of Bacillus mycoides Provides Insights into the Species Ecology and Evolution

Bacillus mycoides is poorly known despite its frequent occurrence in a wide variety of environments. To provide direct insight into its ecology and evolutionary history, a comparative investigation of the species pan-genome and the functional gene categorization of 35 isolates obtained from soil samples from northeastern Poland was performed. The pan-genome of these isolates is composed of 20,175 genes and is characterized by a strong predominance of adaptive genes (∼83%), a significant amount of plasmid genes (∼37%), and a great contribution of prophages and insertion sequences. The pan-genome structure and phylodynamic studies had suggested a wide genomic diversity among the isolates, but no correlation between lineages and the bacillus origin was found. Nevertheless, the two B. mycoides populations, one from Białowieża National Park, the last European natural primeval forest with soil classified as organic, and the second from mineral soil samples taken in a farm in Jasienówka, a place with strong anthropogenic pressure, differ significantly in the frequency of genes encoding proteins enabling bacillus adaptation to specific stress conditions and production of a set of compounds, thus facilitating their colonization of various ecological niches. Furthermore, differences in the prevalence of essential stress sigma factors might be an important trail of this process. Due to these numerous adaptive genes, B. mycoides is able to quickly adapt to changing environmental conditions.Izabela Święcicka: [email protected] Fiedoruk - Department of Microbiology, Medical University of Bialystok, Bialystok, PolandJustyna M. 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Royal Jelly Aliphatic Acids Contribute to Antimicrobial Activity of Honey

Honey is valued for its therapeutic qualities which are attributed among others to its antibacterial multifactorial properties. However, all the factors that influence these properties have not been identified. The present study is focused on the antibacterial action of fatty acids originating from royal jelly, the larval food of honeybees. Aliphatic C8-C12 acids characteristic of this bee product had previously been identified in more than fifty different samples of honey originating from seven countries and in eleven samples of Polish herbhoney. Experiments were performed to ascertain the influence of acidity on the antimicrobial activity of the acids. In acidic nutrient media all tested aliphatic hydroxyacids and unsaturated dicarboxylic acids demonstrated antibacterial action against different microbes with minimal inhibitory concentrations between 0.048 and 3.125 mM. Our results confirm that part of the antibacterial activity of honey contributes to these compounds of bee origin

Chemical Composition and Biological Activity of Argentinian Propolis of Four Species of Stingless Bees

The chemical composition of propolis of four species of stingless bees (SLBs) from Argentina was determined, and its antibacterial and anticancer activity was evaluated on selected types of microbes and cancer cell lines. Volatile secretions of all propolis samples are formed by 174 C2–C15 organic compounds, mainly mono- and sesquiterpenes and their derivatives. The chromatograms of ether extracts showed 287 peaks, of which 210 were identified. The most representative groups in the extracts of various propolis samples were diterpenoids (mainly resin acids), triterpenoids and phenolic compounds: long-chain alkenyl phenols, resorcinols and salicylates. The composition of both volatile and extractive compounds turned out to be species-specific; however, in both cases, the pairwise similarity of the propolis of Scaptotrigona postica and Tetragonisca fiebrigi versus that of Tetragona clavipes and Melipona quadrifasciata quadrifasciata was observed, which indicated the similarity of the preferences of the respective species when choosing plant sources of resin. The composition of the studied extracts completely lacked flavonoids and phenolcarboxylic acids, which are usually associated with the biological activity and medicinal properties of propolis. However, tests on selected microbial species and cancer cell lines showed such activity. All propolis samples tested against Paenibacillus larvae, two species of Bacillus and E. coli showed biofilm inhibition unrelated to the inhibition of bacterial growth, leading to a decrease in their pathogenicity. Testing the anticancer activity of ether extracts using five types of cell cultures showed that all four types of propolis studied inhibit the growth of cancer cells in a dose- and time-dependent manner. Propolis harvested by T. clavipes demonstrated the highest cytotoxicity on all tested cell lines

Melanin-like pigment production in Luria-Bertoni broth by <i>B</i>. <i>weihenstephanensis</i>.

<p><i>B</i>. <i>cereus</i> ATCC 10987 was used as the negative control.</p

PFGE fingerprints of melanin-positive <i>B</i>. <i>weihenstephanensis</i> isolates and reference strains.

<p>Genomic DNA was digested using NotI. M1, PFG Lambda Ladders; M2, PFG Yeast chromosomes. The values on the left and right are molecular weight marker in kb.</p

The phenotypic similarity and phylogeny among <i>B</i>. <i>weihenstephanensis</i> producing melanin-like pigment and reference strains.

<p>Comparisons between strains based on biochemical API 50CH and API 20E tests were made using simple matching coefficient and clustered with the UPGMA algorithm (A). Phylogenetic trees were constructed based on 16S rDNA gene (B) and seven concatenated housekeeping loci (MLST) (C) using the Neighbor-Joining (NJ) method implemented in MEGA6 software, where branch quality was evaluated using 1,000 replicates bootstraps.</p

Melanin-Like Pigment Synthesis by Soil <i>Bacillus weihenstephanensis</i> Isolates from Northeastern Poland

<div><p>Although melanin is known for protecting living organisms from harmful physical and chemical factors, its synthesis is rarely observed among endospore-forming <i>Bacillus cereus sensu lato</i>. Here, for the first time, we reported that psychrotolerant <i>Bacillus weihenstephanensis</i> from Northeastern Poland can produce melanin-like pigment. We assessed physicochemical properties of the pigment and the mechanism of its synthesis in relation to <i>B</i>. <i>weihenstephanensis</i> genotypic and phenotypic characteristics. Electron paramagnetic resonance (EPR) spectroscopy displayed a stable free radical signal of the pigment from environmental isolates which are consistent with the commercial melanin. Fourier transform infrared spectroscopy (FT-IR) and physicochemical tests indicated the phenolic character of the pigment. Several biochemical tests showed that melanin-like pigment synthesis by <i>B</i>. <i>weihenstephanensis</i> was associated with laccase activity. The presence of the gene encoding laccase was confirmed by the next generation whole genome sequencing of one <i>B</i>. <i>weihenstephanensis</i> strain. Biochemical (API 20E and 50CHB tests) and genetic (Multi-locus Sequence Typing, 16S rRNA sequencing, and Pulsed-Field Gel Electrophoresis) characterization of the isolates revealed their close relation to the psychrotrophic <i>B</i>. <i>weihenstephanensis</i> DSMZ 11821 reference strain. The ability to synthesize melanin-like pigment by soil <i>B</i>. <i>weihenstephanensis</i> isolates and their psychrotrophic character seemed to be a local adaptation to a specific niche. Detailed genetic and biochemical analyses of melanin-positive environmental <i>B</i>. <i>weihenstephanensis</i> strains shed some light on the evolution and ecological adaptation of these bacteria. Moreover, our study raised new biotechnological possibilities for the use of water-soluble melanin-like pigment naturally produced by <i>B</i>. <i>weihenstephanensis</i> as an alternative to commercial non-soluble pigment.</p></div