Bdellovibrio and like organisms (BALO) are obligate predators of Gram-negative bacteria, belonging to the a-and d-proteobacteria. BALO prey using either a periplasmic or an epibiotic predatory strategy, but the genetic background underlying these phenotypes is not known. Here we compare the epibiotic Bdellovibrio exovorus and Micavibrio aeruginosavorus to the periplasmic B. bacteriovorus and Bacteriovorax marinus. Electron microscopy showed that M. aeruginosavorus, but not B. exovorus, can attach to prey cells in a non-polar manner through its longitudinal side. Both these predators were resistant to a surprisingly high number of antibiotic compounds, possibly via 26 and 19 antibiotic-resistance genes, respectively, most of them encoding efflux pumps. Comparative genomic analysis of all the BALOs revealed that epibiotic predators have a much smaller genome (ca. 2.5 Mbp) than the periplasmic predators (ca. 3.5 Mbp). Additionally, periplasmic predators have, on average, 888 more proteins, at least 60% more peptidases, and one more rRNA operon. Fifteen and 219 protein families were specific to the epibiotic and the periplasmic predators, respectively, the latter clearly forming the core of the periplasmic 'predatome', which is upregulated during the growth phase. Metabolic deficiencies of epibiotic genomes include the synthesis of inosine, riboflavin, vitamin B6 and the siderophore aerobactin. The phylogeny of the epibiotic predators suggests that they evolved by convergent evolution, with M. aeruginosavorus originating from a non-predatory ancestor while B. exovorus evolved from periplasmic predators by gene loss.

Abiraterone acetate (AA) is an inhibitor of androgen biosynthesis, though this cannot fully explain its efficacy against androgen-independent prostate cancer. Here, we demonstrate that androgen deprivation therapy depletes androgen-utilizing Corynebacterium spp. in prostate cancer patients and that oral AA further enriches for the health-associated commensal, Akkermansia muciniphila. Functional inferencing elucidates a coinciding increase in bacterial biosynthesis of vitamin K2 (an inhibitor of androgen dependent and independent tumor growth). These results are highly reproducible in a host-free gut model, excluding the possibility of immune involvement. Further investigation reveals that AA is metabolized by bacteria in vitro and that breakdown components selectively impact growth. We conclude that A. muciniphila is a key regulator of AA-mediated restructuring of microbial communities, and that this species may affect treatment response in castrate-resistant cohorts. Ongoing initiatives aimed at modulating the colonic microbiota of cancer patients may consider targeted delivery of poorly absorbed selective bacterial growth agents.

Oral candidiasis is a disease caused by opportunistic species of Candida that normally reside on human mucosal surfaces. The transition of Candida from budding yeast to filamentous hyphae allows for covalent attachment to oral epithelial cells, followed by biofilm formation, invasion and tissue damage. In this study, combinations of Lactobacillus plantarum SD5870, Lactobacillus helveticus CBS N116411 and Streptococcus salivarius DSM 14685 were assessed for their ability to inhibit the formation of and disrupt Candida albicans biofilms. Co-incubation with probiotic supernatants under hyphae-inducing conditions reduced C. albicans biofilm formation by .75 % in all treatment groups. Likewise, combinations of live probiotics reduced biofilm formation of C. albicans by .67 %. When live probiotics or their supernatants were overlaid on preformed C. albicans biofilms, biofilm size was reduced by .63 and .65 % respectively. Quantitative real-time PCR results indicated that the combined supernatants of SD5870 and CBS N116411 significantly reduced the expression of several C. albicans genes involved in the yeast-hyphae transition: ALS3 (adhesin/invasin) by 70 % (P,0.0001), EFG1 (hyphae-specific gene activator) by 47 % (P50.0061), SAP5 (secreted protease) by 49 % (P,0.0001) and HWP1 (hyphal wall protein critical to biofilm formation) by .99 % (P,0.0001). These findings suggest the combination of L. plantarum SD5870, L. helveticus CBS N116411 and S. salivarius DSM 14685 is effective at both preventing the formation of and removing preformed C. albicans biofilms. Our novel results point to the downregulation of several Candida genes critical to the yeast-hyphae transition, biofilm formation, tissue invasion and cellular damage.

Bdellovibrio and like organisms (BALOs) are a group of Gram-negative bacterial predators that are defined as having a periplasmic life cycle, whereby the predator enters into the periplasm of a prey cell. Recently, a predator of Caulobacter crescentus with a novel epibiotic life cycle was identified as a new species - Bdellovibrio exovorus. Therefore, this raises the question as to what determines the type of life cycle of a predator. Six bacterial strains susceptible to predation by B. exovorus JSS were isolated from soil, sewage, and activated sludge. 16S rRNA gene sequence analysis revealed these prey cells to be Acinetobacter johnsonii, Acinetobacter junii, Aeromonas hydrophila, and Delftia acidovorans. The life cycle of B. exovorus was epibiotic on all these prey cells. Environmental samples were enriched with these prey cells; new BALOs were isolated and their life cycle assessed. All new isolates had a periplasmic life cycle. BALOs generally have diverse prey ranges, and thus, not all new prey cells could be used by each new predator. Overall, each prey cell was able to support the growth of predators with either life cycle. Therefore it was confirmed that it is the predator and not the prey that determines the type of life cycle.