Inhibition of Fungal Growth and Induction of a Novel Volatilome in Response to Chromobacterium vaccinii Volatile Organic Compounds.

The study of chemical bioactivity in the rhizosphere has recently broadened to include microbial metabolites, and their roles in niche construction and competition via growth promotion, growth inhibition, and toxicity. Several prior studies have identified bacteria that produce volatile organic compounds (VOCs) with antifungal activities, indicating their potential use as biocontrol organisms to suppress phytopathogenic fungi and reduce agricultural losses. We sought to expand the roster of soil bacteria with known antifungal VOCs by testing bacterial isolates from wild and cultivated cranberry bog soils for VOCs that inhibit the growth of four common fungal and oomycete plant pathogens, and Trichoderma sp. Twenty one of the screened isolates inhibited the growth of at least one fungus by the production of VOCs, and isolates of Chromobacterium vaccinii had broad antifungal VOC activity, with growth inhibition over 90% for some fungi. Fungi exposed to C. vaccinii VOCs had extensive morphological abnormalities such as swollen hyphal cells, vacuolar depositions, and cell wall alterations. Quorum-insensitive cviR - mutants of C. vaccinii were significantly less fungistatic, indicating a role for quorum regulation in the production of antifungal VOCs. We collected and characterized VOCs from co-cultivation assays of Phoma sp. exposed to wild-type C. vaccinii MWU328, and its cviR - mutant using stir bar sorptive extraction and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (SBSE-GC × GC-TOFMS). We detected 53 VOCs that differ significantly in abundance between microbial cultures and media controls, including four candidate quorum-regulated fungistatic VOCs produced by C. vaccinii. Importantly, the metabolomes of the bacterial-fungal co-cultures were not the sum of the monoculture VOCs, an emergent property of their VOC-mediated interactions. These data suggest semiochemical feedback loops between microbes that have co-evolved for sensing and responding to exogenous VOCs.

Draft Genome Sequence of Pseudomonas sp. Strain MWU12-2323, Isolated from a Wild Cranberry Bog in Truro, Massachusetts.

Exploration of novel environments such as low-pH wild cranberry bog soils yields a rich diversity of bacteria, including Pseudomonas spp. Here, we present the draft genome sequence of Pseudomonas sp. strain MWU12-2323, isolated from wild cranberry plant rhizosphere. The genome has secondary metabolite genes encoding carbohydrate polymer-degrading enzymes.

16S rRNA Amplicon Profiling of Cranberry (Vaccinium macrocarpon Ait.) Flower and Berry Surfaces.

Bacterial populations associated with the surfaces of cranberry flowers and early fruits in wetlands bogs in Eastern Massachusetts were examined using pyrosequencing. The composition of bacterial populations was highly dependent on sample site, but the dominant phyla on both flower and berry surfaces were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes.

Draft Genome Sequences of Pseudomonas MWU13-2625 and MWU12-2115, Isolated from a Wild Cranberry Bog at the Cape Cod National Seashore.

Two highly similar Pseudomonas sp. genome sequences from wetland bog soil isolates with draft genomes of ~6.3 Mbp are reported. Although the exact taxonomic placement and environmental roles of these bacteria are unclear, predicted genes for stress tolerance, antibiotic resistance, and a type VI secretion system were detected.

Draft Genome Sequence of Pseudomonas sp. Strain MWU13-2860, Isolated from a Wild Cranberry Bog in Truro, Massachusetts.

Pseudomonas sp. strain MWU13-2860 was isolated from the rhizosphere of wild cranberry plants and is not closely related to Pseudomonas spp. frequently isolated from soil. Its genome is 7.2 Mbp, with 61.24% G+C content, and contains homologs that may encode the carbohydrate-degrading enzymes xylanase, laccase, cellulase, alginate lyase, amylase, and chitinase.

Draft Genome Sequence of Pseudomonas sp. Strain MWU12-2534b, Isolated from a Wild Cranberry Bog in Truro, Massachusetts.

An unknown Pseudomonas sp. most closely related to Pseudomonas ficuserectae and Pseudomonas protegens was isolated from the rhizospheres of wild cranberry plants in the Cape Cod National Seashore, in the United States. The draft genome of MWU12-2534b is 6.7 Mbp, has 63.32% GC content, and contains multiple potential virulence and antibiotic resistance genes.

Draft Genome Sequence of Aquitalea sp. Strain MWU14-2217, Isolated from a Wild Cranberry Bog in Provincetown, Massachusetts.

Aquitalea sp. strain MWU14-2217 was isolated from wild cranberry bog soils in the Cape Cod National Seashore. The draft genome is 4.3 Mbp with 4,133 coding sequences and contains predicted genes for phenazines, colicins, siderophores, and putative exporters of these compounds and genes responsible for motility and biofilm formation.