"I Like and Prefer to Work Alone": Social Anxiety, Academic Self-Efficacy, and Students' Perceptions of Active Learning

Although active learning improves student outcomes in science, technology, engineering, and mathematics (STEM) programs, it may provoke anxiety in some students. We examined whether two psychological variables, social anxiety (psychological distress relating to the fear of negative evaluation by others) and academic self-efficacy (confidence in one's ability to overcome academic challenges), interact with student perceptions of evidence-based instructional practices (EBIPs) and associate with their final grades in a STEM-related course. Human anatomy and physiology students in community college courses rated various EBIPs for their perceived educational value and their capacity to elicit anxiety (N = 227). In general, practices causing students the most anxiety (e.g., cold calling) were reported by students as having the least educational value. When controlling for students' self-reported grade point averages, socially anxious students rated several EBIPs as more anxiety inducing, whereas high-efficacy students reported less anxiety surrounding other EBIPs. Furthermore, mediation analysis revealed that individual differences in academic self-efficacy at the beginning of the term explained some of the negative association between students' social anxiety levels and final grades in the course. Our results, obtained in a community college context, support a growing body of evidence that social anxiety and academic self-efficacy are linked with how students perceive and perform in an active-learning environment.

Effects of Fatty Acids on Growth and Poly-3-hydroxybutyrate Production in Bacteria

The effects of saturated and unsaturated fatty acids (lauric acid, palmitic acid, steric acid, oleic acid, linoleic acid, soybean oil) on Sphaerotilus natans, 0B17 (Pseudomonas sp.), and recombinant Escherichia coli DH5(/pUC19/CAB were studied. Oleic acid enhances Poly-3-hydroxybutyrate (PHB) production in these three bacterial strains, suggesting that the single double bond of the acid activates the polyhydroxylkanoate accumulation enzymatic reaction. Under the effect of lauric acid and linoleic acid, the growth of S. natans and 0B17 were totally inhibited. However, the enhanced PHB accumulation in recombinant E. coli was observed.

Microbial synthesis and characterization of physiochemical properties of polyhydroxyalkanoates (PHAs) produced by bacteria isolated from activated sludge obtained from the municipal wastewater works in Hong Kong

The first objective of this study was the measurement of physical properties of P(3HB-co-3HV) copolymers with different (hydroxybutyrate) HB to (hydroxyvalerate) HV ratios produced by Bacillus cereus (TRY2) isolated from activated sludge. The 3HV PHBV copolymers were 0.05, 22.6, 39.2, 54.1, and 69.1 mol%, respectively. The second objective was to study possible waste water treatment and production of PHAs at the same time by B. cereus (TRY2) and Pseudomonas spp. (TOB17) (both were isolated from activated sludge), recombinant Bacillus DH5alpha, and a combination of the above three bacteria. The results were satisfactory; the maximum COD and TOC of the sewage sludge reduced were 53.5% and 67.5%, respectively.

Construction of recombinant Escherichia coli strains for production of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate)

Plastic wastes constitute a worldwide environmental problem, and the demand for biodegradable plastics has become high. One of the most important characteristics of microbial polyesters is that they are thermoplastic with environmentally degradable properties. In this study, pUC19/PHA was cloned and transformed into three different Escherichia coli strains. Among the three strains that were successfully expressed in the production of polyhydroxyalkanoates (PHA), E. coli HMS174 had the highest yield in the production of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (P[HB-HV]). The cell dry weight and PHA content of recombinant HMS174 reached as high as 10.27 g/L and 43% (w/w), respectively, in fed-batch fermentor culture. The copolymer of PHA, P(HB-HV), was found in the cells, and the biopolymers accumulated were identified and analyzed by gas chromatography, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. We demonstrated clearly that the E. coli host for PHA production has to be carefully selected to obtain a high yield. The results obtained indicated that a superior E. coli with high PHA production can be constructed with a desirable ratio of P(HB-HV), which has potential applications in industry and medicine.

Sphaerotilus natans isolated from activated sludge and its production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Sphaerotilus natans is a sheathed bacterium existing in the activated sludge of wastewater treatment plants. It is one of the filamentous bacteria causing the bulking and foaming difficulties of activated sludge. Isolating the strain and culturing it in an axenic environment could not only provide the metabolic knowledge of the strains that would be useful in the development of wastewater treatment methods, but also could enable us to gain an understanding of the mechanism by which poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (poly[3-HB-co-3-HV]) is produced by this strain. This article reports the screening and isolation of the strain from the activated sludge using the Nile blue staining method together with Fourier transform infrared analysis. We investigated the ability of the selected strain to produce poly(3-HB-co-3-HV) copolymer using glucose and peptone, or by adding valeric acid or sodium propionate as precursor. Proper precursor feeding could dramatically enhance its 3HV content in the copolymer P(3HB-co-3HV). By controlling the different feeding times in fed-batch fermentation, different desired copolymers were obtained with 15, 40, and 70% 3HV mole fraction of the copolymer. Polymer properties were analyzed by gas chromatography, differential scanning calorimetry, thermo-gravimetry, and nuclear magnetic resonance analysis.

Production of polyhydroxybutyrate by Bacillus species isolated from municipal activated sludge

Plastic wastes are considered to be severe environmental contaminants causing waste disposal problems. Widespread use of biodegradable plastics is one of the solutions, but it is limited by high production cost. Biologic wastewater treatment generates large quantities of biomass as activated sludge. Only a few reports focus on the potential of utilizing resident Bacillus species from activated sludge in polyhydroxbutyrate (PHB) production as well as the production of PHB from food wastes. They have attractive properties such as short generation time, absence of endotoxins, and secretion of both amylases and proteinases that can well utilize food wastes for nutrients, which can further reduce the cost of production of polyhydroxyalkanoates (PHAs). Two PHA-producing strains, HF-1 and HF-2, were isolated from activated sludge. HF-1 outperformed HF-2 in terms of growth and PHB production in hydrolyzed soy and malt wastes. The isolated bacteria was characterized by DNA sequence alignment. Cell extracts of HF-1 were also compared to Bacillus megaterium cell extracts on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The biopolymers accumulated were analyzed by gas chromatography, nuclear magnetic resonance, and Fourier transform infrared methods.

Septation in Zymomonas mobilis

Freeze-etching and thin sectioning have been used to demonstrate that the gram-negative rod, Zymomonas mobilis ATCC 29191, divides by septation. During this division process the plasma membrane and peptidoglycan grow symmetrically inwards into the cytoplasm at the cell centre, leaving the outer membrane behind at the cell surface. The outer membrane continues to grow causing it to bleb vesicles into the external milieu. Once the septum aperture has closed, the nascent peptidoglycan of the septum splits in two; next, the outer membrane travels inwards between the two new peptidoglycan layers separating the cells. Once this inward growth is finished, cell separation is complete.