Efficacy of UVC-LED in water disinfection on Bacillus species with consideration of antibiotic resistance issue

• Published in: Journal of hazardous materials Vol. 386; p. 121968
• Main Authors: Shen, Liang, Griffith, Tiffany Maria, Nyangaresi, Paul Onkundi, Qin, Yi, Pang, Xin, Chen, Guolong, Li, Minglun, Lu, Yinghua, Zhang, Baoping
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.03.2020
• Subjects: Antibiotic resistance; Bacillus; Bacillus - drug effects; Bacillus - genetics; Bacillus - radiation effects; Disinfection; Disinfection - methods; Drug Resistance, Bacterial - genetics; Drug Resistance, Bacterial - radiation effects; Genes, Bacterial - radiation effects; Photolysis; Tetracycline; Tetracycline - pharmacology; Ultraviolet Rays; UVC-LED; Water Purification - methods; UVC-LED; Disinfection; Bacillus; Antibiotic resistance; Tetracycline
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.121968

[Display omitted] •Apply UVC-LED to treat G+ tetracycline resistant Bacillus sp. for the first time.•268 nm is more effective than 275 nm for TRB and TRG treatment.•UVC-LED can nearly 100 % remove TRB but not completely suppression TRG even at high fluences.•TRB can repair significantly after irradiation by UVC-LED.•Resistance of TRB decreased after UVC-LED irradiation and increased after repair. Ultraviolet light emitting diode (UV-LED) has attracted extensive attention as a new technology to replace traditional mercury lamp for water disinfection. This study reported for the first time the application of UVC-LEDs in range of 200−280 nm for the treatment of two Gram-positive tetracycline resistant bacteria (TRB) from Bacillus species and their tetracycline resistant gene (TRG). The results showed that UVC-LEDs can inactivate TRB up to 5.7-log and inhibit TRG expression, especially at 268 nm. The required fluence was approximate to that of the referential non-resistant bacteria using the same UVC-LED, but far less than that of TRB using mercury lamp. After UVC-LED irradiation, photoreactivation was the dominant mechanism to repair TRB, just like non-resistant bacteria. But contrary to non-resistant bacteria, the regrowth ratio of TRB was remarkably high at 24 h since the end of the irradition, nevertheless the number of the regrown bacteria in the irradiated water was still less than that in the non-irradiated water. Whereas TRB restored resistance after repair even applying 268 nm at a fluence up to 46.08 mJ/cm2 (maximum in this study). This study highlights the merits of UVC-LED to effectively inactivate TRB in a prompt, energy-efficient and resistance-reducing way, while future study on TRB regrowth and resistance resilience is needed.