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This study aimed to characterize commensal microbiota on the skin before and after wearing masks, and to characterize the microbiota on the surface of used masks after 1 week of drying. From the 13 human subjects (age range, 19-26 years), mean bacterial concentrations of (6.1 ± 11.0) × 10

Objectives Profiling of oral microbiota has traditionally been performed using conventional methods. These methods are relatively time-consuming and labor-intensive. Metagenomic analysis of oral microbiota using high-speed next-generation sequencing is a highly promising technology. However, it is expensive. This study sought to develop a simple and cost-effective profiling method for oral microbiota using 16S rRNA gene polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of PCR-amplified 16S ribosomal RNA genes. Methods Oral isolates of 59 bacterial species from human saliva, including Streptococcus, Actinomyces, and Veillonella, were cultured anaerobically on CDC Anaerobe 5% sheep blood agar plates. Genomic DNA was extracted from single colonies and 16S rRNA genes were PCR-amplified using the 27F and 1492R universal primers. The PCR products were purified and characterized by single digestion with HpaII restriction endonuclease. 16S rRNA gene sequences were obtained from the GenBank database, and the expected restriction profiles were compared with the RFLP patterns obtained from agarose gel electrophoresis. Results Sixty-five RFLP patterns were obtained from 27 genera and 59 species. The expected fragment sizes of these species were calculated based on GenBank 16S rRNA gene sequences. Fifty-nine patterns were obtained from the analysis of GenBank sequences. The RFLP patterns produced with HpaII distinguished many oral bacterial species. RFLP patterns enabling identification of oral bacteria were generated. The 16S rRNA gene PCR-RFLP analysis did not require expensive equipment and reagents and was cost-effective. Conclusion PCR-RFLP analysis based on 16S rRNA genes could be an alternative method for oral microbiota analysis in smaller laboratories.

Breast milk is a valuable and useful source of nutrition; however, surplus milk is routinely discarded for hygiene reasons despite an unclear scientific basis. Here, we profiled the microbiota of expressed breast milk before and after feeding with an artificial nipple and examined the bacterial survival in breast milk stored at 4 °C.Eleven mother-baby pairs were included in the study. Samples of expressed breast milk were collected before and after feeding with an artificial nipple and examined both immediately (0 h) and after storage for 3 and 12 h at 4 °C. Each sample was inoculated onto a blood agar plate and incubated anaerobically and aerobically at 37 °C. Genomic DNA was extracted from individual bacterial colonies, which were identified by 16S rRNA gene sequencing.Before feeding, the bacterial counts at 0 and 12 h were (1.4 ± 1.6) × 10Bacteria were present in the breast milk before feeding. Although the main component of the microbiota shifted from Staphylococcus to Streptococcus species after feeding, these results suggest that surplus expressed breast milk may be preserved safely in a refrigerator for at least 12 h after feeding with an artificial nipple.

Objectives To clarify the characteristics and growth of bacteria that may infiltrate liquid baby formula during feeding and after storage for more than 3 h, the transfer of oral bacteria through artificial nipples, and bacterial survival in liquid baby formula and a baby drink were examined immediately after drinking and after storage at 4 °C for 12 h and 24 h. Methods Thirteen human subjects (aged 19–24 years) were asked to drink approximately 50 mL of liquid baby formula and a baby drink, via the artificial nipple of a baby bottle. Samples of the remaining liquid after storage at 4 °C for 12 h and 24 h were inoculated onto blood agar plates and incubated anaerobically at 37 °C for 7 days. Genomic DNA was extracted from individual colonies, and the bacterial species were identified by 16S rRNA gene sequencing. Results The mean concentrations of bacteria in the liquid baby formula were (2.6 ± 2.8) × 104 and (4.1 ± 6.6) × 104 colony-forming unit/mL after storage at 4 °C for 12 h and 24 h, respectively. Streptococcus (43.2%), Veillonella (9.3%), and Schaalia (8.2%) species were recovered from the remaining liquid baby formula after storage at 4 °C for 12 h. In contrast, no bacteria were detected in the remaining baby drink after storage at 37 °C for 24 h. Conclusions The levels of bacteria immediately after drinking and after storage at 4 °C for 12 h or 24 h were similar, suggesting that remaining liquid baby formula may be preserved safely in a refrigerator for more than 3 h.

The survival of bacteria in the sports drink and orange juice remaining in and at the mouth of bottles after direct drinking was examined after immediately drinking and incubation at 37 °C for 24 h.Nine healthy participants were asked to drink approximately 100 mL of a plastic bottled sports drink or orange juice. The samples were cultured anaerobically at 37 °C for 7 days. Genomic DNA was extracted from the resulting individual colonies, and bacterial species were identified using 16 S rRNA gene sequencing.The mean amount of bacteria in the remaining sports drink and orange juice, immediately after drinking, were (1.6 ± 2.3) × 10The bacterial levels differed significantly from the previously reported levels in bottled tea 24 h after drinking, suggesting that remaining drinks with low pH levels can be preserved for a longer period.