Analysis of University student responses to the pandemic in a formal microbiology assessment.

During the coronavirus pandemic, second year students on the BSc molecular biology and genetics degree at Istanbul Technical University sat an open-ended online exam for a microbiology course in which one of the compulsory questions asked how the course had helped them during the first phase of the pandemic (April-July 2020). Fifty of 69 students gave consent for their (anonymous) responses to be analysed in order to discern any key ways in which their knowledge had been applied. The aim of the study was to investigate whether taking an advanced microbiology course increases understanding of the SARS-CoV-2 pandemic and has a positive impact on student behaviours with respect to public health practices. Findings were divided into four major themes: course content (information), application of course content to behaviour change (practice), professionalism, and their 'audience' while at home in lockdown (family and friends). Social distancing, wearing facemasks, hand and surface hygiene were described as important behaviours, with this practice informed by their basic microbiology knowledge. This paper describes a scenario where rote assessment can be used to assess wider scientific literacy with respect to application in society, providing students with an opportunity to incorporate and apply their learning into real-life situations, whilst tutors can assess constructivist learning, conceptual understanding and impact on student behaviour

Evolutionary engineering and molecular characterization of cobalt-resistant Rhodobacter sphaeroides

With its versatile metabolism including aerobic and anaerobic respiration, photosynthesis, photo-fermentation and nitrogen fixation, Rhodobacter sphaeroides can adapt to diverse environmental and nutritional conditions, including the presence of various stressors such as heavy metals. Thus, it is an important microorganism to study the molecular mechanisms of bacterial stress response and resistance, and to be used as a microbial cell factory for biotechnological applications or bioremediation. In this study, a highly cobalt-resistant and genetically stable R. sphaeroides strain was obtained by evolutionary engineering, also known as adaptive laboratory evolution (ALE), a powerful strategy to improve and characterize genetically complex, desired microbial phenotypes, such as stress resistance. For this purpose, successive batch selection was performed in the presence of gradually increased cobalt stress levels between 0.1–15 mM CoCl2 for 64 passages and without any mutagenesis of the initial population prior to selection. The mutant individuals were randomly chosen from the last population and analyzed in detail. Among these, a highly cobalt-resistant and genetically stable evolved strain called G7 showed significant cross-resistance against various stressors such as iron, magnesium, nickel, aluminum, and NaCl. Growth profiles and flame atomic absorption spectrometry analysis results revealed that in the presence of 4 mM CoCl2 that significantly inhibited growth of the reference strain, the growth of the evolved strain was unaffected, and higher levels of cobalt ions were associated with G7 cells than the reference strain. This may imply that cobalt ions accumulated in or on G7 cells, indicating the potential of G7 for cobalt bioremediation. Whole genome sequencing of the evolved strain identified 23 single nucleotide polymorphisms in various genes that are associated with transcriptional regulators, NifB family-FeMo cofactor biosynthesis, putative virulence factors, TRAP-T family transporter, sodium/proton antiporter, and also in genes with unknown functions, which may have a potential role in the cobalt resistance of R. sphaeroides

Temperature resistant mutants of Rhodobacter capsulatus generated by a directed evolution approach and effects of temperature resistance on hydrogen production

Hydrogen (H-2) is a promising alternative energy carrier which can be produced biologically. Rhodobacter capsulatus, a non-sulfur purple photosynthetic bacterium, can produce H-2 under nitrogen-limited, photoheterotrophic conditions by using reduced carbon sources such as simple organic acids. Outdoor closed photobioreactors; used for biological H-2 production are located under direct sunlight, as a result; bioreactors are exposed to temperature fluctuations during day time. In this study to overcome this problem, temperature-resistant mutants (up to 42 degrees C) of R. capsulatus were generated in this study by a directed evolution approach. Eleven mutant strains of R. capsulatus DSM 1710 were obtained by initial ethyl methane sulfonate (EMS) mutagenesis of the wild-type strain, followed by batch selection at gradually increasing temperatures up to 42 degrees C under respiratory conditions. The genetic stability of the mutants was tested and eight were genetically stable. Moreover, H-2 production of mutant strains was analyzed; five mutants produced higher amounts of H-2 when compared to the DSM 1710 wild-type strain and three mutants produced less H-2 by volume. The highest H-2- producing mutant (B41) produced 24% more H-2 compared to wild type, and the mutant with lowest H-2-production capacity (A52) generated 7% less H-2 compared to the wild type. These results indicated that heat resistance of R. capsulatus can be improved by directed evolution, which is a useful tool to improve industrially important microbial properties. To understand molecular changes that confer high temperature-resistance and high hydrogen production capacity to these mutants, detailed transcriptomic and proteomic analyses would be necessary. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Physiological and genetic analysis of cellular sodium and lithium response/resistance behavior using the yeast Saccharomyces cerevisiae as a model organism

The yeast Saccharomyces cerevisiae is a simple eukaryote and an excellent model organism for molecular biology. In this study, a NaCl-resistant S. cerevisiae mutant obtained by inverse metabolic engineering was used as a model to investigate responses and resistance behavior to NaCl, LiCl, KCl, TMA, spermine and sorbitol stresses., at physiological and genetic levels. The physiological spot test results revealed that the NaCl-resistant yeast mutant showed higher resistance to LiCl and NaCl. Gene expression analysis by qRT-PCR revealed that ENA6 and NHA1 genes of the mutant were induced in the absence and presence of LiCl and NaCl. The dysfunction of Na+/H+ antiporters are related to several diseases such as hypertension, epilepsy, postischemic myocardial arrhythmia, gastric and kidney disease, diarrhea, and glaucoma. Thus, the NaCl-resistant yeast mutant could be used to understand cellular sodium and lithium resistance mechanisms and the function of Na+/H+ antiporters also in higher eukaryotic organisms, including humans

Evolutionary engineering and molecular characterization of a caffeine-resistant Saccharomyces cerevisiae strain

Caffeine is a naturally occurring alkaloid, where its major consumption occurs with beverages such as coffee, soft drinks and tea. Despite a variety of reports on the effects of caffeine on diverse organisms including yeast, the complex molecular basis of caffeine resistance and response has yet to be understood. In this study, a caffeine-hyperresistant and genetically stable Saccharomyces cerevisiae mutant was obtained for the first time by evolutionary engineering, using batch selection in the presence of gradually increased caffeine stress levels and without any mutagenesis of the initial population prior to selection. The selected mutant could resist up to 50 mM caffeine, a level, to our knowledge, that has not been reported for S. cerevisiae so far. The mutant was also resistant to the cell wall-damaging agent lyticase, and it showed cross-resistance against various compounds such as rapamycin, antimycin, coniferyl aldehyde and cycloheximide. Comparative transcriptomic analysis results revealed that the genes involved in the energy conservation and production pathways, and pleiotropic drug resistance were overexpressed. Whole genome re-sequencing identified single nucleotide polymorphisms in only three genes of the caffeine-hyperresistant mutant; PDR1, PDR5 and RIM8, which may play a potential role in caffeine-hyperresistance. Graphic abstrac