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The aim of this study was to investigate the prevalence of Vibrionaceae family in retail seafood products available in the Qidong market during the summer of 2023 and to characterize Vibrio parahaemolyticus isolates, given that this bacterium is the leading cause of seafood-associated food poisoning. We successfully isolated a total of 240 Vibrionaceae strains from a pool of 718 seafood samples. The breakdown of the isolates included 146 Photobacterium damselae, 59 V. parahaemolyticus, 18 V. campbellii, and 11 V. alginolyticus. Among these, P. damselae and V. parahaemolyticus were the predominant species, with respective prevalence rates of 20.3% and 8.2%. Interestingly, all 59 isolates of V. parahaemolyticus were identified as non-pathogenic. They demonstrated proficiency in swimming and swarming motility and were capable of forming biofilms across a range of temperatures. In terms of antibiotic resistance, the V. parahaemolyticus isolates showed high resistance to ampicillin, intermediate resistance to cefuroxime and cefazolin, and were sensitive to the other antibiotics evaluated. The findings of this study may offer valuable insights and theoretical support for enhancing seafood safety measures in Qidong City. [ABSTRACT FROM AUTHOR]

Pathogenic bacteria's metabolic adaptation for survival and proliferation within hosts is a crucial aspect of bacterial pathogenesis. Here, we demonstrate that citrate, the first intermediate of the tricarboxylic acid (TCA) cycle, plays a key role as a regulator of gene expression in Staphylococcus aureus. We show that citrate activates the transcriptional regulator CcpE and thus modulates the expression of numerous genes involved in key cellular pathways such as central carbon metabolism, iron uptake and the synthesis and export of virulence factors. Citrate can also suppress the transcriptional regulatory activity of ferric uptake regulator. Moreover, we determined that accumulated intracellular citrate, partly through the activation of CcpE, decreases the pathogenic potential of S. aureus in animal infection models. Therefore, citrate plays a pivotal role in coordinating carbon metabolism, iron homeostasis, and bacterial pathogenicity at the transcriptional level in S. aureus, going beyond its established role as a TCA cycle intermediate. Author summary: Citrate is the first intermediate of the TCA cycle, and its classic role is as a participant in metabolic reactions. In this study, we explored the non-metabolic role of citrate in Staphylococcus aureus. The results suggested that citrate can influence central carbon metabolism, iron homeostasis and the expression of virulence factors by modulating the regulatory activity of the catabolite control protein E (CcpE) and ferric uptake regulator (Fur). For instance, we revealed a new axis, named citrate-CcpE-pycA, was responsible for controlling the endogenous biosynthesis of aspartate, which likely resulted in changes in metabolic adaptation in the host and influenced the pathogenesis of this important human pathogen. Thus, citrate serves as a key signaling molecule for the modulation of gene expression in S. aureus. [ABSTRACT FROM AUTHOR]

The utilization of a nanoporous (NP) GaN fabricated by electrochemical etching has been demonstrated to be effective in the fabrication of a high-performance ultraviolet (UV) photodetector (PD). However, the NP-GaN PD typically exhibits a low light-dark current ratio and slow light response speed. In this study, we present three types of UV PDs based on an unetched GaN, NP-GaN distributed Bragg reflector (DBR), and NP-GaN-DBR with a Ga2O3 single-crystal film (Ga2O3/NP-GaN-DBR). The unetched GaN PD does not exhibit a significant photoresponse. Compared to the NP-GaN-DBR PD device, the Ga2O3/NP-GaN-DBR PD demonstrates a larger light-dark current ratio (6.14 × 103) and higher specific detectivity (8.9 × 1010 Jones) under 365 nm at 5 V bias due to its lower dark current (3.0 × 10−10 A). This reduction in the dark current can be attributed to the insertion of the insulating Ga2O3 between the metal and the NP-GaN-DBR, which provides a thicker barrier thickness and higher barrier height. Additionally, the Ga2O3/NP-GaN-DBR PD device exhibits shorter rise/decay times (0.33/0.23 s) than the NP-GaN-DBR PD, indicating that the growth of a Ga2O3 layer on the DBR effectively reduces the trap density within the NP-GaN DBR structure. Although the device with a Ga2O3 layer presents low photoresponsivity (0.1 A/W), it should be feasible to use Ga2O3 as a dielectric layer based on the above-mentioned reasons. [ABSTRACT FROM AUTHOR]