Scholarworks
ScholarWorks is an open access repository for the capture of the intellectual work of Montana State University (MSU) in support of its teaching, research and service missions. MSU ScholarWorks is a central point of discovery for accessing, collecting, sharing, preserving, and distributing knowledge to the Montana State University community and the world.
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Solubility of 2,5-Furandicarboxylic Acid in Pure and Mixed Organic Solvent Systems at 293 K Predicted Using Hansen Solubility Parameters
(American Chemical Society, 2024-07) Molinaro, Jacob M.; Carroll, M.; Marchan, Gabriela T.; Wettstein, Stephanie G.
Central to the production of polyethylene furanoate (PEF), a bioplastic that could potentially replace petroleum-derived plastics, is 2,5-furandicarboxylic acid (FDCA). FDCA is a chemical derived from biomass that has low solubility in traditionally used solvents such as water. Thus, identifying solvents that can solubilize significant amounts of FDCA could allow for lower PEF production costs. In this study, FDCA solubility was investigated in nine pure solvents including H2O, acetonitrile (ACN), γ-valerolactone (GVL), γ-butyrolactone (GBL), ethanol (EtOH), methanol (MeOH), dimethyl sulfoxide (DMSO), sulfolane (SULF), and tetrahydrofuran (THF), eight binary, and three ternary solvent blends at 293 K. For all binary systems excluding DMSO and MeOH, the solubility of FDCA increased 1.5–65 times compared to the pure organic solvent, and the FDCA solubility was at least 10 times higher when compared to pure water. Specifically, the 20/80 w/w H2O/DMSO system solubilized 23.1 wt % FDCA, the highest of any binary blend studied, and 190 times more solubility than in pure water. In 20/80 w/w H2O/THF, the FDCA solubility was 60 times higher than pure water. In ternary blends that included DMSO, H2O, and either GVL, THF, or SULF, solubility increased by at least 6.6 times relative to the pure secondary organic component and 54 times relative to pure water. Using Hansen solubility parameters (HSPs), the radius of interaction (Ri, j) was found to be more strongly correlated to FDCA solubility than individual HSPs or the total solubility parameter. A MATLAB-based optimization code was developed and successful in minimizing the Ri, j of a solvent blend to maximize FDCA solubility in binary and ternary aqueous solvents.
Microcosm Assessment of a DNA Probe Applied to Aerobic Degradation of cis-1,2-Dichloroethene by Polaromonas sp. Strain JS666
(Wiley, 2010-05) Giddings, Clolle G.S.; Jennings, Laura K.; Gossett, James M.
A molecular biological tool based on an organism-specific DNA sequence does not necessarily indicate in situ activity but serves important functions of evaluating the potential for biodegradation and mapping the distribution of an organism. Currently, DNA-based probes are accepted as evaluative tools for site assessment. However, these techniques are far from standardized, and information on precision is usually lacking. Here, we present the development and evaluation of a DNA probe for Polaromonas sp. strain JS666, a bacterium that couples growth to aerobic oxidation of cis-1,2-dichloroethene (cDCE), and is therefore a promising candidate for bioaugmentation at sites where cDCE has accumulated in aerobic zones. The DNA probe was used in conjunction with quantitative polymerase chain reaction to track the abundance of JS666 in microcosms. This series of studies has allowed explicit resolution of the accuracy and precision of the probe and its correlation with variations in microcosm performance. We determined that the method is sufficient to monitor distribution of JS666 at bioaugmented sites. We found within environmental, mixed cultures, that the DNA target does not persist long after cell death, demonstrating that positive result from the probe is a strong indicator that degradation can occur in suitable environmental conditions. Finally, in the absence of suspected predation, the probe accurately and precisely tracks growth. Collectively, the studies appear to validate the utility of the molecular probe for site assessment in a bioaugmentation context.
Polyamines and linear DNA mediate bacterial threat assessment of bacteriophage infection
(Proceedings of the National Academy of Sciences, 2023-02) de Mattos, Camilla D.; Faith, Dominick R.; Nemudryi, Artem; Schmidt, Amelia K.; Bublitz, DeAnna C.; Hammond, Lauren R.; Kinnersley, Margie; Schwartzkopf, Caleb M.; Robinson, Autumn J.; Joyce, Alex; Michaels, Lia A.; Brzozowski, Robert S.; Coluccio, Alison; Xing, Denghui David; Uchiyama, Jumpei; Jennings, Laura K.; Eswara, Prahathees; Wiedenheft, Blake; Secor, Patrick R.
Monitoring the extracellular environment for danger signals is a critical aspect of cellular survival. However, the danger signals released by dying bacteria and the mechanisms bacteria use for threat assessment remain largely unexplored. Here, we show that lysis of Pseudomonas aeruginosa cells releases polyamines that are subsequently taken up by surviving cells via a mechanism that relies on Gac/Rsm signaling. While intracellular polyamines spike in surviving cells, the duration of this spike varies according to the infection status of the cell. In bacteriophage-infected cells, intracellular polyamines are maintained at high levels, which inhibits replication of the bacteriophage genome. Many bacteriophages package linear DNA genomes and linear DNA is sufficient to trigger intracellular polyamine accumulation, suggesting that linear DNA is sensed as a second danger signal. Collectively, these results demonstrate how polyamines released by dying cells together with linear DNA allow P. aeruginosa to make threat assessments of cellular injury.
The Depletion Mechanism Actuates Bacterial Aggregation by Exopolysaccharides and Determines Species Distribution & Composition in Bacterial Aggregates
(Frontiers Media SA, 2022-06) Secor, Patrick R.; Michaels, Lia A.; Bublitz, DeAnna C.; Jennings, Laura K.; Singh, Pradeep K.
Bacteria in natural environments and infections are often found in cell aggregates suspended in polymer-rich solutions, and aggregation can promote bacterial survival and stress resistance. One aggregation mechanism, called depletion aggregation, is driven by physical forces between bacteria and high concentrations of polymers in the environment rather than bacterial activity per se. As such, bacteria aggregated by the depletion mechanism will disperse when polymer concentrations fall unless other adhesion mechanisms supervene. Here we investigated whether the depletion mechanism can actuate the aggregating effects of Pseudomonas aeruginosa exopolysaccharides for suspended (i.e. not surface attached) bacteria, and how depletion affects bacterial inter-species interactions. We found that cells overexpressing the exopolysaccharides Pel and Psl remained aggregated after short periods of depletion aggregation whereas wild-type and mucoid P. aeruginosa did not. In co-culture, depletion aggregation had contrasting effects on P. aeruginosa’s interactions with coccus- and rod-shaped bacteria. Depletion caused S. aureus (cocci) and P. aeruginosa (rods) to segregate from each other and S. aureus to resist secreted P. aeruginosa antimicrobial factors resulting in species co-existence. In contrast, depletion aggregation caused P. aeruginosa and Burkholderia sp. (both rods) to intermix, enhancing type VI secretion inhibition of Burkholderia by P. aeruginosa, leading to P. aeruginosa dominance. These results show that in addition to being a primary cause of aggregation in polymer-rich suspensions, physical forces inherent to the depletion mechanism can promote aggregation by some self-produced exopolysaccharides and determine species distribution and composition of bacterial communities.
A Filamentous Bacteriophage Protein Inhibits Type IV Pili To Prevent Superinfection of Pseudomonas aeruginosa
(American Society for Microbiology, 2022-02) Schmidt, Amelia K.; Fitzpatrick, Alexa D.; Schwartzkopf, Caleb M.; Faith, Dominick R.; Jennings, Laura K.; Coluccio, Alison; Hunt, Devin J.; Michaels, Lia A.; Hargil, Aviv; Chen, Qingquan; Bollyky, Paul L.; Dorward, David W.; Wachter, Jenny; Rosa, Patricia A.; Maxwell, Karen L.; Secor, Patrick R.
Pseudomonas aeruginosa is an opportunistic pathogen that causes infections in a variety of settings. Many P. aeruginosa isolates are infected by filamentous Pf bacteriophage integrated into the bacterial chromosome as a prophage. Pf virions can be produced without lysing P. aeruginosa. However, cell lysis can occur during superinfection, which occurs when Pf virions successfully infect a host lysogenized by a Pf prophage. Temperate phages typically encode superinfection exclusion mechanisms to prevent host lysis by virions of the same or similar species. In this study, we sought to elucidate the superinfection exclusion mechanism of Pf phage. Initially, we observed that P. aeruginosa that survive Pf superinfection are transiently resistant to Pf-induced plaquing and are deficient in twitching motility, which is mediated by type IV pili (T4P). Pf utilize T4P as a cell surface receptor, suggesting that T4P are suppressed in bacteria that survive superinfection. We tested the hypothesis that a Pf-encoded protein suppresses T4P to mediate superinfection exclusion by expressing Pf proteins in P. aeruginosa and measuring plaquing and twitching motility. We found that the Pf protein PA0721, which we termed Pf superinfection exclusion (PfsE), promoted resistance to Pf infection and suppressed twitching motility by binding the T4P protein PilC. Because T4P play key roles in biofilm formation and virulence, the ability of Pf phage to modulate T4P via PfsE has implications in the ability of P. aeruginosa to persist at sites of infection.