Questiomycin A

Pseudomonas chlororaphishas been demonstrated as a valuable source of antimicrobial metabolites for plant disease biocontrol and biopesticide development. Although phenazine-1-carboxylic acid (PCA) secreted byP. chlororaphishas been commercialized as an antifungal biopesticide, it shows poor antibacterial activity. Questiomycin A, with versatile antibacterial activities, is mainly discovered in some well-known phenazine-producing strains but not inPseudomonas. Its low titer hinders practical applications. In this work, a metabolite was first identified as Questiomycin A inP. chlororaphis-derived strain HT66ΔphzBΔNat. Subsequently, Questiomycin A has been elucidated to share the same biosynthesis process with PCA by gene deletion andin vitroassays. Through rational metabolic engineering, heterologous phenoxazinone synthase introduction, and medium optimization, the titer reached 589.78 mg/L inP. chlororaphis, the highest production reported to date. This work contributes to a better understanding of Questiomycin A biosynthesis and demonstrates a promising approach to developing a new antibacterial biopesticide inPseudomonas.

Questiomycin A (1) along with three new compounds, questiomycins C-E (2-4), were isolated from culture ofAlteromonassp. D, an algicidal marine bacterium, guided by algal lethality assay using the raphidophyte,Chattonella antiqua, one of the causative organisms of harmful algal bloom. The structures of1-4were assigned on the basis of their spectrometric and spectroscopic data. Compounds1to4exhibited algicidal activity againstC. antiquawith LC50values ranging from 0.18 to 6.37 M. Co-cultivation experiment revealed that1was produced only when the microalgae and the bacterium are in close contact, suggesting that some interactions between them trigger the biosynthesis of questiomycins. These results suggested that the algicidal bacteria such asAlteromonassp. D can control microalgae chemically in marine ecosystem.

In order to provide an opportunity for community pharmacists to actively learn about infection control, this study created learning materials through a board game format and verified characteristics of learning by determining and comparing evaluation according to viewpoint and motivational effects between a lecture and the game. To create the board game, we collected cases of infection from 30 community pharmacists. The game was created using collected and created case studies, and we held a workshop on infection control. Participants were assigned to a lecture (n=32) or game group (n=27) and completed a questionnaire before and after the workshop. The questionnaire included the evaluation according to viewpoint based on the ministry's curriculum guidelines and the motivational effect of Keller's ARCS motivation model. In the evaluation according to viewpoint, the lecture group scores were significantly higher on "knowledge and understanding" than the game group scores. In the comparison of the motivational effects, the game group was significantly higher in three out of the four items of the ARCS motivation model, "Attention", "Relevance", and "Satisfaction". These results indicate that learning through the game aroused the curiosity of the learners, increased the learning outcome, and maintained certain levels of motivation. In addition, the evaluation according to viewpoint showed that the lecture group understood the key concepts and knowledge regarding infection control, whereas there was a possibility that the game group required additional motivational factors for learning and maintaining motivation level.