Lignin-derived (e.g. phenolic) compounds can compromise the bioconversion of lignocellulosic biomass to fuels and chemicals due to their toxicity and recalcitrance. The lipid-accumulating bacterium Rhodococcus opacus PD630 has recently emerged as a promising microbial host for lignocellulose conversion to value-added products due to its natural ability to tolerate and utilize phenolics. To gain a better understanding of its phenolic tolerance and utilization mechanisms, we adaptively evolved R. opacus over 40 passages using phenol as its sole carbon source (up to 373% growth improvement over wild-type), and extensively characterized two strains from passages 33 and 40. The two adapted strains showed higher phenol consumption rates (∼20 mg/l/h) and ∼2-fold higher lipid production from phenol than the wild-type strain. Whole-genome sequencing and comparative transcriptomics identified highly-upregulated degradation pathways and putative transporters for phenol in both adapted strains, highlighting the important linkage between mechanisms of regulated phenol uptake, utilization, and evolved tolerance. Our study shows that the R. opacus mutants are likely to use their transporters to import phenol rather than export them, suggesting a new aromatic tolerance mechanism. The identified tolerance genes and pathways are promising candidates for future metabolic engineering in R. opacus for improved lignin conversion to lipid-based products.

Activating and inhibiting receptors of lymphocytes collect valuable information about their mikròs kósmos. This information is essential to initiate or to turn off complex signaling pathways. Irrespective of these advances, our knowledge on how these intracellular activation cascades are coordinated in a spatiotemporal manner is far from complete. Amongst multiple explanations, the scaffolding proteins have emerged as a critical piece of this evolutionary tangram. Amongst many, IQGAP1 is one of the essential scaffolding proteins that coordinate multiple signaling pathways. IQGAP1 possesses multiple protein interaction motifs to achieve its scaffolding functions. Using these domains, IQGAP1 has been shown to regulate a number of essential cellular events. This includes actin polymerization, tubulin multimerization, MTOC formation, calcium/calmodulin signaling, Pak/Raf/Mek1/2-mediated Erk1/2 activation, formation of maestrosome, E-cadherin and CD44-mediated signaling and GSK3/APC-mediated β-catenin activation. In this review we summarize the recent developments and exciting new findings of cellular functions of IQGAP1.

Antimicrobial resistance threatens the efficacy of antimicrobial treatment options, including last-line-of-defense drugs. Understanding how this resistance develops can help direct antimicrobial stewardship efforts and is critical to designing the next generation of antimicrobial therapies. Here we determine how Corynebacterium striatum, a skin commensal and opportunistic pathogen, evolved high-level resistance to a drug of last resort, daptomycin. Through a single mutation, this pathogen was able to remove the daptomycin’s target, phosphatidylglycerol (PG), from the membrane and evade daptomycin’s bactericidal activity. We found that additional compensatory changes were not necessary to support the removal of PG and replacement with phosphatidylinositol (PI). The ease with which C. striatum evolved high-level resistance is cause for alarm and highlights the importance of screening new antimicrobials against a wide range of clinical pathogens which may harbor unique capacities for resistance evolution.

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MRSA infections of surgically implanted subcutaneous vascular catheters (SISVCs) cause serious morbidity in patients with chronic illnesses. Previous in vitro and murine models demonstrated synergistic interaction of equimolar concentrations of meropenem/piperacillin/tazobactam (M/P/T; VIO-001) against MRSA infection. We investigated the pharmacokinetics (PK) and efficacy of VIO-001 for treatment of MRSA bacteremia in immunocompetent rabbits with SISVCs. In PK studies, we determined that optimal dosing to achieve T/4×MIC T/MIC for the duration of 3-3.30h required 1h-infusion with Q4h dosing. Study groups in efficacy experiments consisted of M/P/T combination of 100/150/100 (MPT100), 200/300/200 (MPT200), 400/600/400 (MPT400) mg/kg, vancomycin (VAN) at 15 mg/kg, and untreated controls (UC). The inoculum of MRSA isolate USA300-TCH1516 (1×10 3 ) was administered via the SISCV on Day-1 and locked for 24h. The 8-day therapy started 24h post-inoculation. There was significant reduction of MRSA in blood cultures from the SISVCs in all treatment groups with full clearance on Day-4 vs UC (p<0.05). Consistent with clearance of SISVC-related infection, full eradication of MRSA was achieved in lungs, heart, liver, spleen, and kidneys at end of study vs UC (p <0.01). These results strongly correlated with time-kill data, where MPT in the range of 4/6/4 to 32/48/32 μg/mL demonstrated significant six-log decrease in bacterial burden vs UC (p<0.01). In summary, VIO-001 demonstrated a favorable PK/PD profile and activity against SISCV MRSA infection, bacteremia, and disseminated infection. This rabbit model provides a new system for understanding new antimicrobial agents against MRSA SISVC-related infection and these data provide a basis for future clinical investigation.