A novel bacterial strain of acetic acid bacteria capable of producing riboflavin was isolated from the soil sample collected in Wuhan, China. The isolated strain was identified as Gluconobacter oxydans FBFS97 based on several phenotype characteristics, biochemicals tests, and 16S rRNA gene sequence conducted. Furthermore, the complete genome sequencing of the isolated strain has showed that it contains a complete operon for the biosynthesis of riboflavin. In order to obtain the maximum concentration of riboflavin production, Gluconobacter oxydans FBFS97 was optimized in shake flask cultures through response surface methodology employing Plackett–Burman design (PBD), and Central composite design (CCD). The results of the pre-experiments displayed that fructose and tryptone were found to be the most suitable sources of carbon and nitrogen for riboflavin production. Then, PBD was conducted for initial screening of eleven minerals (FeSO₄, FeCl₃, KH₂PO₄, K₂HPO₄, MgSO₄, ZnSO₄, NaCl, CaCl₂, KCl, ZnCl₂, and AlCl₃.6H₂O) for their significances on riboflavin production by Gluconobacter oxydans strain FBFS97. The most significant variables affecting on riboflavin production are K₂HPO₄ and CaCl₂, the interaction affects and levels of these variables were optimized by CCD. After optimization of the medium compositions for riboflavin production were determined as follows: fructose 25 g/L, tryptone 12.5 g/L, K₂HPO₄ 9 g/L, and CaCl₂ 0.06 g/L with maximum riboflavin production 23.24 mg/L.

The present study aimed to characterize melanin pigment extracted from Gluconobacter oxydans FBFS 97. After 14 days of culture at 28 °C in GY (glucose and yeast extract) liquid-state medium, G. oxydans FBFS97 produce the maximum melanin, up to about 12–15 mg/L. The physicochemical characteristics of the extracted melanin showed an ability to dissolve in 1 mol/L NaOH or 1 mol/L KOH, and insolubility in water and most organic solvents, such as chloroform and petroleum ether. The extracted melanin was confirmed to be exact melanin by ultraviolet-visible spectrophotometry, Fourier-transform infrared spectroscopy, thin-layer chromatography, elemental analysis, and scanning electron microscopy. The UV-visible spectrum of G. oxydans FBFS97 exhibited a maximum absorption peak at 230 nm. Extracted melanin demonstrated significant free radical-scavenging activity by DPPH and ABTS methods. The IC₅₀ value of the extracted melanin for scavenging 50% DPPH radicals was 36.94 μg/mL, and the IC₅₀ value of antioxidant activity for ABTS was 4.06 μg/mL. Hence, G. oxydans FBFS97 has the potential to be a new candidate for melanin production.

Authors MSc, Sport Management, School of Physical Education and Sport Training, Shanghai University of Sport, China PhD, Physical Education and Sport Coaching, Shanghai University of Sport, China, Department of Physical Activity, Albaydha University, Yemen albrahnaif@gmail.com Associate Professor, Physical Activity, Sport Media, Department of Physical Activity, Faculty of Education and Science, Albaydha University, Yemen Associate Professor,… اقرأ المزيد »Building Winning Teams: A Review of Team Trust, Conflict, and Performance in Sports Organizations

University students now use artificial intelligence (AI) tools in several academic activities, including information retrieval, writing support, and problem-solving. While these technologies may enhance learning efficiency, effective student engagement with AI requires relevant psychological characteristics as well as technology-related competencies. Earlier studies indicate that learner characteristics, including mindfulness, may relate to patterns of engagement with digital technologies. Mindfulness, AI literacy, and AI self-efficacy have been studied separately, but their combined relationships remain insufficiently examined. Accordingly, this study examined the associations among these three variables in university students and assessed whether specific dimensions of AI literacy were involved in the statistical association between mindfulness and students’ self-rated readiness to use AI-supported tools for academic purposes. The study used a cross-sectional survey design. Undergraduate students at Shandong Xiehe University in China completed an online questionnaire. After screening the responses, 929 valid questionnaires were retained for analysis. Participants were between 18 and 22 years of age. Mindfulness, AI literacy, and AI self-efficacy were assessed using established self-report scales. The analysis first summarized the main study variables using descriptive statistics. Bivariate relationships among mindfulness, AI literacy, and AI self-efficacy were examined using Pearson correlation analysis. PROCESS Model 4 was applied with 5,000 bootstrap resamples to test the proposed indirect-association model. The results indicated positive relationships between mindfulness, AI literacy, and AI self-efficacy. Regression analyses also indicated that mindfulness showed significant relationships with each AI literacy dimension, namely AI awareness, AI usage, AI evaluation, and AI ethics. Mindfulness showed significant positive associations on multiple dimensions of AI self-efficacy. The mediation analyses identified AI literacy represented a significant indirect pathway linking mindfulness with AI self-efficacy. Specifically, the dimensions of AI awareness, AI usage, and AI evaluation showed significant indirect effects, AI ethics did not show consistent indirect effects across the tested models. The findings show that mindfulness was positively associated with AI literacy and AI self-efficacy among university students. They also suggest that students reporting higher AI literacy also reported greater perceived capability in using AI-supported tools, indicating that technological understanding may be statistically related to the association between mindfulness and perceived competence. The results show links between psychological awareness, AI literacy, and students’ engagement with AI tools in higher education. The results may inform the development of AI literacy initiatives in higher education that support students’ informed, insightful, and confident use of AI tools in academic contexts.

Background: There is a lack of investigation into the dynamics of blood lipids before, during, and after diurnal fasting, especially in inactive men. Objective: This study determined dynamic changes in blood lipids in inactive men before, during, and after they underwent diurnal fasting. Methods: A total of 44 young men aged a mean 27.6 (SD 5.8) years were recruited to evaluate their habitual physical activity and diet using a questionnaire developed for this study. Body composition was evaluated using a bioelectrical impedance analysis machine (Tanita BC-980). An 8-ml blood sample was collected to evaluate blood lipids and glucose. All measurements were taken 2-3 days before Ramadan, during Ramadan (at week 2 and week 3), and 1 month after Ramadan. A 1-way repeated measures ANOVA was used to compare the measured variables before, during, and after the month of Ramadan. When a significant difference was found, post hoc testing was used. Differences were considered significant at P<.05. Results: There was a significant reduction in low-density lipoprotein during Ramadan compared to before and after Ramadan (83.49 mg/dl at week 3 vs 93.11 mg/dl before Ramadan [P=.02] and 101.59 mg/dl after Ramadan [P=.007]). There were significant elevations in fasting blood glucose (74.60 mmol/L before Ramadan vs 81.52 mmol/L at week 3 [P=.03] and 86.51 mmol/L after Ramadan [P=.01]) and blood pressure (109 mm Hg before Ramadan vs 114 mm Hg after Ramadan; P=.02) reported during and even after the month of Ramadan, although both fasting blood glucose and blood pressure were within normal levels. Conclusions: Ramadan fasting could be an independent factor in reducing low-density lipoprotein. Further investigations are encouraged to clarify the impact of diurnal fasting on blood lipids in people with special conditions.