Draft Genome Sequence of the Symbiotic Frankia sp. strain B2 isolated from root nodules of Casuarina cunninghamiana found in Algeria

Frankia sp. strain B2 was isolated from Casuarina cunninghamiana nodules. Here, we report the 5.3-Mbp draft genome sequence of Frankia sp. strain B2 with a G+C content of 70.1 % and 4,663 candidate protein-encoding genes. Analysis of the genome revealed the presence of high numbers of secondary metabolic biosynthetic gene clusters

Exploring cultivable Bacteria from the prokaryotic community associated with the carnivorous sponge Asbestopluma hypogea

Combining culture-dependent and independent approaches, we investigated for the first time the cultivable fraction of the prokaryotic community associated with the carnivorous sponge Asbestopluma hypogea. The heterotrophic prokaryotes isolated from this tiny sponge were compared between specimens freshly collected from cave and maintained in aquarium. Overall, 67 isolates obtained in pure culture were phylogenetically affiliated to the bacterial phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. This cultivable diversity was lower than the prokaryotic diversity obtained by previous pyrosequencing study and comparable to that of another Mediterranean demosponge, the filter-feeding Phorbas tenacior. Furthermore, using fluorescence in situ hybridization, we visualized bacterial and archaeal cells, confirming the presence of both prokaryotes in A.hypogea tissue. Approximately 16% of the bacterial isolates tested positive for chitinolytic activity, suggesting potential microbial involvement in the digestion processes of crustacean prey by this carnivorous sponge. Additionally, 6% and 16% of bacterial isolates revealed antimicrobial and antioxidant activities, respectively. One Streptomyces sp. S1CA strain was identified as a promising candidate for the production of antimicrobial and antioxidant secondary metabolites as well as chitinolytic enzymes. Implications in the context of the sponge biology and prey-feeding strategy are discussed

Molecular Methods for Research on Actinorhiza

International audienceActinorhizal root nodules result from the interaction between a nitrogen-fixing actinomycete from the genus Frankia and roots of dicotyledonous trees and shrubs belonging to 25 genera within 8 plant families. Most actinorhizal plants can reach high rates of nitrogen fixation comparable to those found in root nodule symbiosis of the legumes. As a consequence, these trees are able to grow in poor and disturbed soils and are important elements in plant communities worldwide. While the basic knowledge of these symbiotic associations is still poorly understood, actinorhizal symbioses emerged recently as original systems to explore developmental strategies to form nitrogen-fixing nodules. Many tools have been developed in recent years to explore the interaction between Frankia and actinorhizal plants including molecular biology, biochemistry, and genomics. However, technical difficulties are often encountered to explore these symbiotic interactions, mainly linked to the woody nature of the plant species and to the lack of genetic tools for their bacterial symbionts. In this chapter, we report an inventory of the main recent molecular tools and techniques developed for studying actinorhizae

Characterization of Leucocin B-KM432Bz from Leuconostoc pseudomesenteroides isolated from Boza, and comparison of its efficiency to Pediocin PA-1

Publication of this article was funded by the Stellenbosch University Open Access Fund.The original publication is available at http://www.plosone.org/A bacteriocin-producing bacterium was isolated from boza and identified as Leuconostoc pseudomesenteroides KM432Bz. The antimicrobial peptide was purified and shown to be identical to other class IIa bacteriocins: leucocin A from Leuconostoc gelidum UAL-187 and Leuconostoc pseudomesenteroides QU15 and leucocin B from Leuconostoc carnosum Ta11a. The bacteriocin was named leucocin B-KM432Bz. Leucocin B-KM432Bz gene cluster encodes the bacteriocin precursor (lcnB), the immunity protein (lcnI) and the dedicated export machinery (lcnD and lcnE). A gene of unknown and non-essential function (lcnC), which is interrupted by an insertion sequence of the IS30 family, is localized between lcnB and lcnD. The activity of leucocin B-KM432Bz requires subunit C of the EIIt Man mannose permease, which is the receptor for entry into target cells. The determination of the minimum inhibitory concentrations revealed the lowest values for leucocin B-KM432Bz over Listeria strains, with 4 to 32 fold better efficiency than pediocin PA-1.Stellenbosch UniversityPublishers' versio

Exploring cultivable Bacteria

Combining culture-dependent and independent approaches, we investigated for the first time the cultivable fraction of the prokaryotic community associated with the carnivorous sponge Asbestopluma hypogea. The heterotrophic prokaryotes isolated from this tiny sponge were compared between specimens freshly collected from cave and maintained in aquarium. Overall, 67 isolates obtained in pure culture were phylogenetically affiliated to the bacterial phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. This cultivable diversity was lower than the prokaryotic diversity obtained by previous pyrosequencing study and comparable to that of another Mediterranean demosponge, the filter-feeding Phorbas tenacior. Furthermore, using fluorescence in situ hybridization, we visualized bacterial and archaeal cells, confirming the presence of both prokaryotes in A.hypogea tissue. Approximately 16% of the bacterial isolates tested positive for chitinolytic activity, suggesting potential microbial involvement in the digestion processes of crustacean prey by this carnivorous sponge. Additionally, 6% and 16% of bacterial isolates revealed antimicrobial and antioxidant activities, respectively. One Streptomyces sp. S1CA strain was identified as a promising candidate for the production of antimicrobial and antioxidant secondary metabolites as well as chitinolytic enzymes. Implications in the context of the sponge biology and prey-feeding strategy are discussed