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The solid culture method for measuring the efficiency of ultraviolet (UV) disinfection of airborne bacteria is time-consuming, typically taking 12–48 h. To expedite such experiments, this study proposed a liquid culture method assisted by adenosine triphosphate (ATP) analysis, as a liquid culture is faster than a solid culture, and measurement of ATP does not require waiting for visible colonies to form. Escherichia coli (E. coli) was used as the experimental bacterium. This study first compared the log reduction of bacteria in liquid as measured by the proposed method and by the traditional solid culture method. The minimum liquid culture time was determined for different bacterial concentration ranges. Finally, the feasibility of the proposed method was validated by UV disinfection experiments on airborne bacteria. The results indicated that the proposed method measured a similar log reduction to that of the solid culture method in liquid experiments. The minimum liquid culture time for E. coli in 105-106 colony forming units (CFU)/mL was 2 h. The validation experiments demonstrated that the proposed method is capable of measuring the UV disinfection efficiency of airborne bacteria. The proposed method can accelerate laboratory experiments on UV disinfection of airborne bacteria, which in turn can support the effective design and utilization of UV disinfection in real life. [Display omitted] • A liquid culture assisted by adenosine triphosphate analysis method was proposed. • The minimum liquid culture time was determined for different concentration ranges. • The proposed method can be used to measure UV disinfection of airborne bacteria. [ABSTRACT FROM AUTHOR]

Involved in most aerobic biochemical processes, oxygen affects cellular functions, and organism behaviors. Protein synthesis, as the underlying biological process, is unavoidably affected by the regulation of oxygen delivery and utilization. Bypassing the cell wall, cell-free protein synthesis (CFPS) systems are well adopted for the precise oxygen regulation analysis of bioprocesses. Here a reliable flow platform was developed for measuring and analyzing the oxygen regulation on the protein synthesis processes by combining Escherichia coli-based CFPS systems and a tube-in-tube reactor. This platform allows protein synthesis reactions conducted in precisely controlled oxygen concentrations. For analysis of the intrinsic role of oxygen in protein synthesis, O2-tuned CFPS systems were explored with transcription-translation related parameters (transcripts, energy, reactive oxygen species, and proteomic pathway analysis). It was found that 2% of oxygen was the minimum requirement for protein synthesis. There was translation-related protein degradation in the high oxygen condition leading to a reduction. By combining the precise gas level controlling and open biosystems, this platform is also potential for fundamental understanding and clinical applications by diverse gas regulation in biological processes.

Mechanical cleaning of dentures is effective in preventing infections such as aspiration pneumonia and denture stomatitis. For denture wearers with a physical handicap and the elderly, however, mechanical cleaning can present problems. The aim of this study was to investigate the effect of coating denture base acrylic resin with titanium dioxide (TiO2) in the inhibition of oral microbial adhesion. We prepared uniformly sized acrylic resin plates (10 mm × 10 mm × 0·5 mm), which were divided into two groups (a non-coated group and a TiO2-coated group). The plates were immersed in cultured Streptococcus sanguinis or Candida albicans and incubated for 24 h. After incubation, each plate was washed to remove loosely adherent microorganisms, and then incubated for a further 24 h. Adenosine triphosphate (ATP) content of the microorganisms was evaluated using a reagent containing benzalkonium, which extracts intra-cellular ATP. In addition, to determine biofilm formation, we also observed each plate by scanning electron microscopy (SEM). We found that the ATP content of both S. sanguinis and C. albicans was reduced by the TiO2 coating ( P = 0·000). Observation by SEM confirmed that the TiO2 coating inhibited biofilm formation. The results indicate that a TiO2 coating on a denture base acrylic resin inhibits adhesion of S. sanguinis and C. albicans. [ABSTRACT FROM AUTHOR]

Involved in most aerobic biochemical processes, oxygen affects cellular functions, and organism behaviors. Protein synthesis, as the underlying biological process, is unavoidably affected by the regulation of oxygen delivery and utilization. Bypassing the cell wall, cell-free protein synthesis (CFPS) systems are well adopted for the precise oxygen regulation analysis of bioprocesses. Here a reliable flow platform was developed for measuring and analyzing the oxygen regulation on the protein synthesis processes by combining Escherichia coli -based CFPS systems and a tube-in-tube reactor. This platform allows protein synthesis reactions conducted in precisely controlled oxygen concentrations. For analysis of the intrinsic role of oxygen in protein synthesis, O 2 -tuned CFPS systems were explored with transcription-translation related parameters (transcripts, energy, reactive oxygen species, and proteomic pathway analysis). It was found that 2% of oxygen was the minimum requirement for protein synthesis. There was translation-related protein degradation in the high oxygen condition leading to a reduction. By combining the precise gas level controlling and open biosystems, this platform is also potential for fundamental understanding and clinical applications by diverse gas regulation in biological processes., (Copyright © 2020 Lin, Zhou, Zhu, Deng, Zhang and Lu.)