Yuan-Song Zhang,Lei Yuan,Fedrick C. Mgomi,Cao-Wei Chen,Yang Wang,Zhen-Quan Yang,Xin-an Jiao
Cronobacter sakazakii, a foodborne pathogen, can contaminate powdered infant formula (PIF) and cause life-threatening meningitis, necrotizing colitis and meningoencephalitis in infants. Bacteriophages are increasingly considered an efficient approach to target pathogenic microorganisms. In the current study, four virulent phages that can infect C. sakazakii were isolated from sewage samples, and their biological and complete genomic characteristics were analyzed. A comparative genomic analysis was performed to investigate the functional genes and phylogenetic evolution of the four phages. The results revealed that all four phages belonged to the Ackermannviridae family. Notably, the viral burst size of the phages ranged from 10 to 250 PFU/cell, following a latent period of 5 min to 20 min. Moreover, phages were stable over a pH range of 4 to 10 and a temperature range of 50 ℃ to 60 ℃. The full length of the complete genomes of the four phages ranged from 41,929 bp to 146,806 bp, containing lysis genes but no virulence genes. Phylogenetic tree analysis showed that the four phages were members of two distinct genetic groups with a significant genetic evolutionary distance between each C. sakazakii phage. Furthermore, the antibacterial assay revealed that all phages could inhibit the growth of C. sakazakii for up to 24 h. Taken together, the four phages have huge prospects as additives in dairy products to counter C. sakazakii .
Hang Jia,Zewei Wang,Rui Cai,Zhouli Wang,Yahong Yuan,Tianli Yue
Bacterial drug resistance caused by the abuse of antibiotics poses a serious threat to human health. Thus, the development of alternative strategies for the replacing of antibiotics is necessary. Herein, a hierarchical three-dimensional Bi 2 S 3 (BS) nanoflowers were facile fabricated and employed as supporter for the growth of silver nanoparticles (Ag NPs). Combining the excellent antimicrobial activity of Ag NPs, the as-resulted Ag/BS exhibited broad-spectrum antibacterial activity against pathogenic bacteria. Investigation on antibacterial mechanism revealed the treatment of Ag/BS damages the bacterial cell membrane , leading to the loss of intracellular substances. The compromised membrane caused the reduction of membrane bound enzymes activity , resulting in the arrest of metabolic activity. Simultaneously, Ag/BS broke the bacterial antioxidant defense system by raising the intracellular ROS levels, caused the oxidative damage , resulting in the loss of bacterial viability. Moreover, the satisfactory biocompatibility and effective antibacterial performance of Ag/BS were confirmed by performing in vitro cytotoxicity and in vivo antibacterial assay. Accordingly, this work opens up possibility for the construction of Bi 2 S 3 based multifunctional nanomaterials and its application for pathogenic bacteria control.
危险品化学品经营许可证（带存储）