Search Results (5)

Hydrocarbon fuel biofouling and biocorrosion require expensive cleanup of aviation infrastructures unless appropriate sustainment measures are applied. The identification of novel biological control agents offers promising alternatives to the current chemical biocides used in fuel sustainment. In this study, 496 microbial fuel isolates from our in-house repository were screened to identify new endogenously produced antimicrobial compounds. Using agar plug screening, liquid culture growth testing, and Jet A fuel culture assays, the two fuel-isolate strains Pseudomonas protegens #133, and Bacillus subtilis #232 demonstrated promising biocontrol activity against bacteria, yeast, and filamentous fungi. Liquid chromatography-quadrupole time of flight tandem mass spectrometry (LC-QTOF-MS/MS) of #232 culture filtrate identified several common lipopeptide antimicrobials including gageostatin C, gageopeptin B, and miscellaneous macrolactins. In contrast, LC-QTOF-MS/MS identified the siderophore pyochelin as one of the predominant compounds in #133 culture filtrate with previously demonstrated antimicrobial effect. Jet fuel microbial consortium culture testing of #133 culture filtrate including flow-cytometry live/dead cell mechanism determination demonstrated antimicrobial action against Gram-positive bacteria. The study concludes that antimicrobial compounds secreted by #133 have bactericidal effects against Gordonia sp. and cause cell death through bacterial lysis and membrane damage with potential applications in the biocidal treatment of hydrocarbon-based aviation fuels. Full article

The model organism Caenorhabditis elegans is used in a variety of applications ranging from fundamental biological studies, to drug screening, to disease modeling, and to space-biology investigations. These applications rely on conducting whole-organism phenotypic assays involving animal behavior and locomotion. In this study, we report a 3D printed compact imaging platform (CIP) that is integrated with a smart-device camera for the whole-organism phenotyping of C. elegans. The CIP has no external optical elements and does not require mechanical focusing, simplifying the optical configuration. The small footprint of the system powered with a standard USB provides capabilities ranging from plug-and-play, to parallel operation, and to housing it in incubators for temperature control. We demonstrate on Earth the compatibility of the CIP with different C. elegans substrates, including agar plates, liquid droplets on glass slides and microfluidic chips. We validate the system with behavioral and thrashing assays and show that the phenotypic readouts are in good agreement with the literature data. We conduct a pilot study with mutants and show that the phenotypic data collected from the CIP distinguishes these mutants. Finally, we discuss how the simplicity and versatility offered by CIP makes it amenable to future C. elegans investigations on the International Space Station, where science experiments are constrained by system size, payload weight and crew time. Overall, the compactness, portability and ease-of-use makes the CIP desirable for research and educational outreach applications on Earth and in space. Full article

Fusarium basal rot (FBR) caused by Fusarium oxysporum f. sp. cepae (FOC) is a major threat to onion (Allium cepa L.) production and marketing worldwide. Finding new sources of FBR-resistance to develop synthetic cultivars is a priority for onion breeders. As there are no FBR-resistant short-day onion cultivars, 85 U.S. National Plant Germplasm System plant introduction onion accessions that originated from 23 different countries were screened for their FBR susceptibility. To compare FBR susceptibility of these accessions at their seedling and mature bulb stages, a susceptible check cultivar, NuMex Crimson, a partially resistant check cultivar, Serrana and its selected population, Serrana-sel, were included in the study. The seedling screening was performed after inoculating silica-sand media with a virulent FOC isolate ‘CSC-515’ at 1.0 × 10⁴ macroconidia g⁻¹ of sand. Each entry was evaluated twice in growth chambers, and percent survival was adjusted to the number of seedlings that germinated in the uninoculated trays. Mature bulbs produced in the field were screened by inoculating transversely cut basal plates with potato dextrose agar plugs containing spores of the same isolate at 3.0 × 10⁴ macroconidia mL⁻¹. FBR severity and incidence were then calculated after 20 days of incubation. Significant variation was found among the accessions for FBR-susceptibility (p < 0.001) at both the seedling and the mature bulb stages. Two sets of 18 accessions were identified either for their higher seedling survival or higher mature bulb FBR-resistance compared to the checks. Among them, PI 256326 (‘Baia Periforme’, the originator cultivar of ‘Serrana’) had a higher seedling survival than both the checks, and a lower mature bulb severity than the susceptible check. Another accession, PI 656956 (‘S015’), exhibited higher seedling survival than the susceptible check and a low FBR severity (4.3 on a 1 to 9 scale) and incidence (41.7%). These two accessions, which were known previously for their high intra-population heterogeneity and root or bulb resistance for FBR, respectively, show promise for incorporating FBR-resistance into short-day onion cultivars. The cultivar rankings could vary in future studies with a range of FOC isolates due to a high cultivar × isolate interaction as observed in past studies. Full article

Fusarium basal rot (FBR) of onion, caused by the soil-borne fungus Fusarium oxysporum f.sp. cepae (FOC), results in a substantial storage loss of marketable bulbs. Seedling and field screening methods, which were used to generate FBR resistant long-day and intermediate-day onion cultivars, were found to be ineffective at increasing FBR resistance in short-day onion cultivars. This study attempted to improve the FBR resistance of seven commercial short-day onion cultivars and two check cultivars when evaluated at their mature bulb stage. Mature bulbs were artificially inoculated with 1 cm diameter potato dextrose agar plugs containing conidia of a virulent FOC isolate, CSC-515, at a concentration of 3 × 10⁴ spore mL⁻¹, after transversely cutting the basal plate tissue. Incubated bulbs, which had few or no FBR symptoms, were selected after 20 d using visual scoring, from 1 (no disease) to 9 (>70% basal plate is infected), and combined in seed production cages to produce the selected generation of a cultivar. Multiple cycles of phenotypic recurrent selection were conducted, and the resultant populations were compared with their respective original populations for FBR severity and incidence, from 2016 to 2019, using the same conidial inoculation method. A variable amount of progress was achieved in reducing FBR severity and incidence in the seven cultivars, with maximum improvement in the most advanced selected populations. FBR development in the advanced selected populations differed between mature bulbs of each entry and was influenced by yearly environmental variation. The progress of FOC infections was slower in resistant bulbs when compared to susceptible bulbs. These results indicated a partial or quantitative resistance against FBR. The partial FBR resistant cultivar populations could be used to develop synthetic short-day FBR resistant cultivars after multi-locational and multi-seasonal field trials. These populations could also be used to study the mechanism(s) of FBR resistance in onion, which has yet to be determined. Full article

The fungi Botrytis cinerea, Fusarium pallidoroseum, and Fusarium moniliforme are the causative agents of several plant diseases and can cause significant crop loss both before and after harvest. Fungicides are employed to control these phytopathogens, but fungicide use has led to an increase in resistance and may negatively affect the environment and human health. Hence, more environmentally sustainable solutions such as biological control methods are needed. The purpose of this study was to screen 22 bacterial isolates for inhibitory activity against fungal phytopathogens. To evaluate antifungal activity, the bacterial isolates were individually spot-inoculated onto Tryptic Soy Agar or de Man, Rogosa, Sharpe agar, and then a plug of fungal-colonized agar was placed onto the center of the isolate-inoculated plate. Plates were incubated at 24 °C for 10 days and fungal growth was evaluated. Nine of the 22 isolates screened inhibited all three fungi; inhibition by these isolates ranged from 51–62%, 60–68%, and 40–61% for B. cinerea, F. pallidoroseum, and F. moniliforme, respectively. Isolates were also screened for biosurfactant activity using the drop-collapse test. Bacillus megaterium, Bacillus coagulans, Bacillus thuringiensis and three Bacillus amyloliquefaciens isolates demonstrated strong biosurfactant activity and suppression of all three fungi, and therefore are recommended for further study. Full article