More Like this

1. An essential periplasmic protein coordinates lipid trafficking and is required for asymmetric polar growth in mycobacteria

   https://doi.org/10.7554/eLife.80395  

   Gupta, Kuldeepkumar R; Gwin, Celena M; Rahlwes, Kathryn C; Biegas, Kyle J; Wang, Chunyan; Park, Jin Ho; Liu, Jun; Swarts, Benjamin M; Morita, Yasu S; Rego, E Hesper (November 2022, eLife)

   Mycobacteria, including the human pathogen Mycobacterium tuberculosis , grow by inserting new cell wall material at their poles. This process and that of division are asymmetric, producing a phenotypically heterogeneous population of cells that respond non-uniformly to stress (Aldridge et al., 2012; Rego et al., 2017). Surprisingly, deletion of a single gene – lamA – leads to more symmetry, and to a population of cells that is more uniformly killed by antibiotics (Rego et al., 2017). How does LamA create asymmetry? Here, using a combination of quantitative time-lapse imaging, bacterial genetics, and lipid profiling, we find that LamA recruits essential proteins involved in cell wall synthesis to one side of the cell – the old pole. One of these proteins, MSMEG_0317, here renamed PgfA, was of unknown function. We show that PgfA is a periplasmic protein that interacts with MmpL3, an essential transporter that flips mycolic acids in the form of trehalose monomycolate (TMM), across the plasma membrane. PgfA interacts with a TMM analog suggesting a direct role in TMM transport. Yet our data point to a broader function as well, as cells with altered PgfA levels have differences in the abundance of other lipids and are differentially reliant on those lipids for survival. Overexpression of PgfA, but not MmpL3, restores growth at the old poles in cells missing lamA . Together, our results suggest that PgfA is a key determinant of polar growth and cell envelope composition in mycobacteria, and that the LamA-mediated recruitment of this protein to one side of the cell is a required step in the establishment of cellular asymmetry. 

   more » « less
2. Stable isotope values of consumers, producers, and organic matter in the Shark River Slough and Taylor Slough, Everglades National Park (FCE LTER), Florida, USA, 2019 – ongoing

   https://doi.org/10.6073/pasta/da36c97eccd5461ba32eecce23a53892  

   Rezek, Ryan (January 2024, Environmental Data Initiative)

   {"Abstract":["Wetland food webs have often been characterized as detrital-based ‘brown’ energy pyramids, whereas the relative role of autotrophic (‘green’) vs. microbial (‘brown’) energy sources falls along a continuum set by physical drivers, as well as autochthonous and allochthonous inputs (Moore et al. 2004; Evans-White & Halvorson 2017) that change with ecosystem development (Schmitz et al. 2006). In the Florida Coastal Everglades (FCE), metabolic imbalances, including the collapse of calcareous periphyton mats, begin with a loss of foundation species primary production and legacy organic matter (Gaiser et al. 2006). This process likely enhances heterotrophic microbial productivity (Schulte 2016) and the supply of detrital energy to consumers by changing bioavailable and recalcitrant carbon supplies (Baggett et al. 2013). A shift from complex periphyton communities to transient planktonic communities under elevated P exposure reduces habitat structure and animal refuges but increases ‘green’ energy supplies and edibility (Trexler et al. 2015; Naja et al. 2017). Multiple sites (n=9) within the FCE were selected to document changes in coastal food webs as a result of eutrophication and increasing hydrologic variability. The project began in 2019 and is currently ongoing.\n \n References:\n Baggett, L. P., Heck, K. L., Frankovich, T. A., Armitage, A. R., & Fourqurean, J. W. (2013). Stoichiometry, growth, and fecundity responses to nutrient enrichment by invertebrate grazers in sub-tropical turtle grass (Thalassia testudinum) meadows. Marine biology, 160, 169-180.\n Evans-White, M. A., and H. M. Halvorson. 2017. Comparing the Ecological Stoichiometry in Green and Brown Food Webs – A Review and Meta-analysis of Freshwater Food Webs. Frontiers in Microbiology 8:1184. \n Gaiser, E. E., Childers, D. L., Jones, R. D., Richards, J. H., Scinto, L. J., & Trexler, J. C. (2006). Periphyton responses to eutrophication in the Florida Everglades: cross‐system patterns of structural and compositional change. Limnology and Oceanography, 51(1part2), 617-630.\n Moore, J. C., E. L. Berlow, D. C. Coleman, P. C. Ruiter, Q. Dong, A. Hastings, N. C. Johnson, K. S. McCann, K. Melville, P. J. Morin, K. Nadelhoffer, A. D. Rosemond, D. M. Post, J. L. Sabo, K. M. Scow, M. J. Vanni, and D. H. Wall. 2004. Detritus, trophic dynamics and biodiversity: Detritus, trophic dynamics and biodiversity. Ecology Letters 7:584–600. \n Naja, M., Childers, D. L., & Gaiser, E. E. (2017). Water quality implications of hydrologic restoration alternatives in the Florida Everglades, United States. Restoration Ecology, 25, S48-S58.\n Schmitz, O. J., Kalies, E. L., & Booth, M. G. (2006). Alternative dynamic regimes and trophic control of plant succession. Ecosystems, 9, 659-672.\n Schulte, Nicholas O., "Controls on Benthic Microbial Community Structure and Assembly in a Karstic Coastal Wetland" (2016). FIU Electronic Theses and Dissertations. 2447. 10.25148/etd.FIDC000233\n Trexler, J. C., Gaiser, E. E., Kominoski, J. S., & Sanchez, J. (2015). The role of periphyton mats in consumer community structure and function in calcareous wetlands: lessons from the Everglades. Microbiology of the everglades ecosystem, 155-179."]} 

   more » « less
3. Antimicrobial Activity of, and Cellular Pathways Targeted by, p -Anisaldehyde and Epigallocatechin Gallate in the Opportunistic Human Pathogen Pseudomonas aeruginosa

   https://doi.org/10.1128/AEM.02482-19  

   Adewunmi, Yetunde; Namjilsuren, Sanchirmaa; Walker, William D.; Amato, Dahlia N.; Amato, Douglas V.; Mavrodi, Olga V.; Patton, Derek L.; Mavrodi, Dmitri V.; Kivisaar, Maia (February 2020, Applied and Environmental Microbiology)

   ABSTRACT Plant-derived aldehydes are constituents of essential oils that possess broad-spectrum antimicrobial activity and kill microorganisms without promoting resistance. In our previous study, we incorporated p -anisaldehyde from star anise into a polymer network called proantimicrobial networks via degradable acetals (PANDAs) and used it as a novel drug delivery platform. PANDAs released p -anisaldehyde upon a change in pH and humidity and controlled the growth of the multidrug-resistant pathogen Pseudomonas aeruginosa PAO1. In this study, we identified the cellular pathways targeted by p -anisaldehyde by generating 10,000 transposon mutants of PAO1 and screened them for hypersensitivity to p -anisaldehyde. To improve the antimicrobial efficacy of p -anisaldehyde, we combined it with epigallocatechin gallate (EGCG), a polyphenol from green tea, and demonstrated that it acts synergistically with p -anisaldehyde in killing P. aeruginosa . We then used transcriptome sequencing to profile the responses of P. aeruginosa to p -anisaldehyde, EGCG, and their combination. The exposure to p -anisaldehyde altered the expression of genes involved in modification of the cell envelope, membrane transport, drug efflux, energy metabolism, molybdenum cofactor biosynthesis, and the stress response. We also demonstrate that the addition of EGCG reversed many p -anisaldehyde-coping effects and induced oxidative stress. Our results provide insight into the antimicrobial activity of p -anisaldehyde and its interactions with EGCG and may aid in the rational identification of new synergistically acting combinations of plant metabolites. Our study also confirms the utility of the thiol-ene polymer platform for the sustained and effective delivery of hydrophobic and volatile antimicrobial compounds. IMPORTANCE Essential oils (EOs) are plant-derived products that have long been exploited for their antimicrobial activities in medicine, agriculture, and food preservation. EOs represent a promising alternative to conventional antibiotics due to their broad-range antimicrobial activity, low toxicity to human commensal bacteria, and capacity to kill microorganisms without promoting resistance. Despite the progress in the understanding of the biological activity of EOs, our understanding of many aspects of their mode of action remains inconclusive. The overarching aim of this work was to address these gaps by studying the molecular interactions between an antimicrobial plant aldehyde and the opportunistic human pathogen Pseudomonas aeruginosa . The results of this study identify the microbial genes and associated pathways involved in the response to antimicrobial phytoaldehydes and provide insights into the molecular mechanisms governing the synergistic effects of individual constituents within essential oils. 

   more » « less
4. One-Step Oxidation of Orange Peel Waste to Carbon Feedstock for Bacterial Production of Polyhydroxybutyrate

   https://doi.org/10.3390/polym15030697  

   Davaritouchaee, Maryam; Mosleh, Imann; Dadmohammadi, Younas; Abbaspourrad, Alireza (February 2023, Polymers)

   Orange peels are an abundant food waste stream that can be converted into useful products, such as polyhydroxyalkanoates (PHAs). Limonene, however, is a key barrier to building a successful biopolymer synthesis from orange peels as it inhibits microbial growth. We designed a one-pot oxidation system that releases the sugars from orange peels while eliminating limonene through superoxide (O2• −) generated from potassium superoxide (KO2). The optimum conditions were found to be treatment with 0.05 M KO2 for 1 h, where 55% of the sugars present in orange peels were released and recovered. The orange peel sugars were then used, directly, as a carbon source for polyhydroxybutyrate (PHB) production by engineered Escherichia coli. Cell growth was improved in the presence of the orange peel liquor with 3 w/v% exhibiting 90–100% cell viability. The bacterial production of PHB using orange peel liquor led to 1.7–3.0 g/L cell dry weight and 136–393 mg (8–13 w/w%) ultra-high molecular weight PHB content (Mw of ~1900 kDa) during a 24 to 96 h fermentation period. The comprehensive thermal characterization of the isolated PHBs revealed polymeric properties similar to PHBs resulting from pure glucose or fructose. Our one-pot oxidation process for liberating sugars and eliminating inhibitory compounds is an efficient and easy method to release sugars from orange peels and eliminate limonene, or residual limonene post limonene extraction, and shows great promise for extracting sugars from other complex biomass materials. 

   more » « less
5. Nutritional Profile and Ecological Interactions of Yeast Symbionts Associated with North American Spruce Beetle (Dendroctonus rufipennis)

   https://doi.org/10.1007/s00248-022-02158-7  

   Davis, Thomas S.; Stewart, Jane E.; Clark, Caitlin; Van Buiten, Charlene (December 2022, Microbial Ecology)

   To better understand functional ecology of bark beetle-microbial symbioses, we characterized yeast associates of North American spruce beetle (Dendroctous rufipennis Kirby) across populations. Seven yeast species were detected; Wickerhamomyces canadensis (Wickerham) Kurtzman et al. (Sachharomycetales: Saccharomycetaceae) was the most common (74% of isolates) and found in all populations. Isolates of W. canadensis were subsequently tested for competitive interactions with symbiotic (Leptographium abietinum, = Grosmannia abietina) and pathogenic (Beauvaria bassiana) filamentous fungi, and isolates were nutritionally profiled (protein and P content). Exposure to yeast headspace emissions had isolate-dependent effects on colony growth of symbiotic and pathogenic fungi; most isolates of W. canadensis slightly inhibited growth rates of symbiotic (L. abietinum, mean effect: − 4%) and entomopathogenic (B. bassiana, mean effect: − 6%) fungi. However, overall variation was high (range: − 35.4 to + 88.6%) and some yeasts enhanced growth of filamentous fungi whereas others were consistently inhibitory. The volatile 2-phenylethanol was produced by W. canadensis and synthetic 2-phenylethanol reduced growth rates of both L. abietinum and B. bassiana by 36% on average. Mean protein and P content of Wickerhamomyces canadensis cultures were 0.8% and 7.2%, respectively, but isolates varied in nutritional content and protein content was similar to that of host tree phloem. We conclude that W. canadensis is a primary yeast symbiont of D. rufipennis in the Rocky Mountains and emits volatiles that can affect growth of associated microbes. Wickerhamomyces canadensis isolates vary substantially in limiting nutrients (protein and P), but concentrations are less than reported for the symbiotic filamentous fungus L. abietinum. 

   more » « less