Horizontal transfer of antibiotic resistance genes within the bacterial communities in aquacultural environment

Very little is known about how microbiome interactions shape the horizontal transfer of antibiotic resistance genes in aquacultural environment. To this end, we first conducted 16S rRNA gene amplicon sequencing to monitor the dynamics of bacterial community compositions in one shrimp farm from 2019 to 2020. Next, co-occurrence analysis was then conducted to reveal the interactions network between Vibrio spp. and other species. Subsequently, 21 V. parahaemolyticus isolates and 15 related bacterial species were selected for whole-genome sequencing (WGS). The 16S rDNA amplicon sequencing results identified a remarkable increase of Vibrio and Providencia in September-2019 and a significant rise of Enterobacter and Shewanella in Septtember-2020. Co-occurrence analysis revealed that Vibrio spp. positively interacted with the above species, leading to the sequencing of their isolates to further understand the sharing of the resistant genomic islands (GIs). Subsequent pan-genomic analysis of V. parahaemolyticus genomes identified 278 horizontally transferred genes in 10 GIs, most of which were associated with antibiotic resistance, virulence, and fitness of metabolism. Most of the GIs have also been identified in Providencia, and Enterobacter, suggesting that exchange of genetic traits might occur in V. parahaemolyticus and other cooperative species in a specific niche. No genetic exchange was found between the species with negative relationships. The knowledge generated from this study would greatly improve our capacity to predict and mitigate the emergence of new resistant population and provide practical guidance on the microbial management during the aquacultural activities

An Integrated Experimental-Computational Investigation of Connected Spaces as Natural Ventilation Typologies

This paper investigates the impact of spatial composition on the effectiveness of passive cooling by natural ventilation in a comparative study of the conical roofed Harran houses in Turkey and a passive solar home in the Midwest of the United States. While the projects are distinct and are situated in two extreme climate zones (hot and arid and continental humid) both projects have in common open variable configurations of multiple interconnected spaces. Computational fluid dynamics (CFD) simulations using OpenFoam were used to investigate the fundamental airflow characteristics and the resulting interior temperature and velocity profiles. The simulations were initialized as well as validated with measured field data. Subsequently, we tested the impact of the interconnected spatial composition of the buildings on their cooling potentials. This was accomplished by simulating variations of the spatial connections with reduced flow path connectivity compared to the original validated cases. Preliminary results regarding changes in temperature and air velocity show higher temperatures and lower velocities in the less connected cell-like spaces and indicate the importance of spatial connectivity for effective cooling by natural ventilation based on variable interaction of vents and flow path.This conference proceeding is published as Ulrike Passe, Mirka Deza, Baskar Ganapathysubramanian, Shan He, Kyle Vansice, Songzhe Xu2, An Integrated Experimental-Computational Investigation of Connected Spaces as Natural Ventilation Typologies. at the 2016 Proceedings of the Symposium on Simulation for Architecture and Urban Design. London United Kingdom, May 16-18, 2016; Session 1; 59-66. Posted with permission.</p

Prevalence of Antibiotic-Resistant Escherichia coli in Drinking Water Sources in Hangzhou City

This study investigated the distribution of antibiotic resistant Escherichia coli (E. coli) and examined the possible relationship between water quality parameters and antibiotic resistance from two different drinking water sources (the Qiantang River and the Dongtiao Stream) in Hangzhou city of China. E. coli isolates were tested for their susceptibility to 18 antibiotics. Most of the isolates were resistant to tetracycline (TE), followed by ampicillin (AM), piperacillin (PIP), trimethoprim/sulfamethoxazole (SXT), and chloramphenicol (C). The antibiotic resistance rate of E. coli isolates from two water sources was similar; For E. coli isolates from the Qiantang River, their antibiotic resistance rates decreased from up- to downstream. Seasonally, the dry and wet season had little impact on antibiotic resistance. Spearman's rank correlation revealed significant correlation between resistance to TE and phenicols or ciprofloxacin (CIP), as well as quinolones (ciprofloxacin and levofloxacin) and cephalosporins or gentamicin (GM). Pearson's chi-square tests found certain water parameters such as nutrient concentration were strongly associated with resistance to some of the antibiotics. In addition, tet genes were detected from all 82 TE-resistant E. coli isolates, and most of the isolates (81.87%) contained multiple tet genes, which displayed 14 different combinations. Collectively, this study provided baseline data on antibiotic resistance of drinking water sources in Hangzhou city, which indicates drinking water sources could be the reservoir of antibiotic resistance, potentially presenting a public health risk