Accumulating evidence has indicated that the multiple drug resistant Vibrio parahaemolyticus may pose a serious threat to public health and economic concerns for humans globally. Here, two lytic bacteriophages, namely vB_VpS_BA3 and vB_VpS_CA8, were isolated from sewage collected in Guangzhou, China. Electron microscopy studies revealed both virions taxonomically belonged to the Siphoviridae family with icosahedral head and a long non-contractile tail. The double-stranded DNA genome of phage BA3 was composed of 58648 bp with a GC content of 46.30% while phage CA8 was 58480 bp with an average GC content of 46.42%. In total, 85 putative open reading frames (ORFs) were predicted in the phage BA3 genome while 84 were predicted in that of CA8. The ORFs were associated with phage structure, packing, host lysis, DNA metabolism, and additional functions. Furthermore, average nucleotide identity analysis, comparative genomic features and phylogenetic analysis revealed that BA3 and CA8 represented different isolates but novel members of the family, Siphoviridae. Regarding the host range of the 61 V. parahaemolyticus isolates, BA3 and CA8 had an infectivity of 8.2 and 36.1%, respectively. Furthermore, ∼100 plaque-forming units (pfu)/cell for phage BA3 and ∼180 pfu/cell for phage CA8 were determined to be the viral load under laboratory growth conditions. Accordingly, the phage-killing assay in vitro revealed that phage CA8 achieved approximately 3.65 log unit reductions. The present results indicate that CA8 is potentially applicable for biological control of multidrug resistant V. parahaemolyticus.

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A whole-cell based method was developed for the regioselective synthesis of arabinocytosine laurate. Among the seven kinds of bacteria strains tested in the acylation reaction, Pseudomonas fluorescens gave the highest productivity and a higher 5′-regioselectivity than 99%. Compared with pure organic solvents, the use of organic solvent mixtures greatly promoted the yield of the whole-cell catalyzed reaction, but showed little influence on the 5′-regioselectivity. Of all the tested solvent mixtures, the best reaction result was found in isopropyl ether/pyridine followed by isopentanol/pyridine. However, the whole-cells showed much lower thermostability in isopropyl ether/pyridine than in THF-pyridine. To better understand the toxic effects of the organic solvents on P. fluorescens whole-cells and growing cells were further examined. Significant influences of organic solvents on the biomass of the cells were found, which differed depending on the type of solvents used. SEM analysis visually revealed the changes in the surface morphology of whole-cells and growing cells cultured in media containing various organic solvents, in terms of surface smoothness, bulges and changed cell sizes. Results demonstrated that organic toxicity to cell structure played an important role in whole-cell mediated catalysis.

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The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a destructive pest that causes serious damage worldwide, particularly to maize cultivars. The microbiota of S. frugiperda might play a role in its development and adaptability to different environments. However, the dynamics of microbial communities in S. frugiperda during its life cycle remain poorly understood. In this study, we used the amplification of the 16S rRNA gene to characterize the microbiome of all developmental stages of S. frugiperda fed with maize and adults fed with an artificial diet. The microbial composition of maize leaves, soil, and artificial diet was analyzed. Alpha diversity indices indicated that the neonate and early-phase larvae had higher bacterial diversity than late-phase larvae, pupae, and adults, and the bacterial diversity of adults fed with natural leaves was higher than that of adults fed an artificial diet. Proteobacteria and Firmicutes were the major phyla found in most life stages of S. frugiperda, especially in adults, sixth instars, and pupae. Neonate and early-phase larvae harbored a higher abundance of OD1 and microbes of unassigned taxonomy. A cooccurrence network of the highly abundant genera within S. frugiperda was then constructed, which revealed a potential interaction between the microbiota in insects, such as Enterococcus and Pseudomonas, and the dietary microbiota. Dynamic changes in bacterial communities led to changes in the metabolic functions of the microbiota across developmental stages. The genera OD1, Enterococcus, Comamonas, and Elizabethkingia were estimated to contribute to most of the functional changes in the microbiota of S. frugiperda. Our findings provide a comprehensive understanding of the composition of S. frugiperda and its dynamic interaction with dietary microbiota.

Vibrio parahaemolyticus causes aquatic vibriosis. Its biofilm protects it from antibiotics; therefore, a new different method is needed to control V. parahaemolyticus for food safety. Phage therapy represents an alternative strategy to control biofilms. In this study, the lytic Vibrio phage vB_VpaP_FE11 (FE11) was isolated from the sewers of Guangzhou Huangsha Aquatic Market. Electron microscopy analysis revealed that FE11 has a typical podovirus morphology. Its optimal stability temperature and pH range were found to be 20–50 °C and 5–10 °C, respectively. It was completely inactivated following ultraviolet irradiation for 20 min. Its latent period is 10 min and burst size is 37 plaque forming units/cell. Its double-stranded DNA genome is 43,397 bp long, with a G + C content of 49.24% and 50 predicted protein-coding genes. As a lytic phage, FE11 not only prevented the formation of biofilms but also could destroy the formed biofilms effectively. Overall, phage vB_VpaP_FE11 is a potential biological control agent against V. parahaemolyticus and the biofilm it produces.

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