Changes in the microbial community of Litopenaeus vannamei larvae and rearing water during different growth stages after disinfection treatment of hatchery water

Effects of potassium monopersulfate on nitrification activity and bacterial community structure of sponge biocarrier biofilm in Litopenaeus vannamei aquaculture system

Effects of potassium monopersulfate (KMPS) on the nitrification activity, aquacultural water quality and bacterial community structure of sponge biocarriers with pre-cultured biofilm (SBBF) were analysed through shaking flask experiments and L. vannamei aquaculture experiments. Changes in the ammonia oxidation rate (AOR) and nitrite oxidation rate (NOR) of SBBF under six KMPS concentration treatments (0, 1, 2, 3, 4 and 5 mg/L) were studied. The results showed that the AOR and NOR of SBBF treated with high concentrations of KMPS (3, 4 and 5 mg/L) were significantly lower than those of the control group (CK) (p < 0.05). However, compared with the first dosing of NH4Cl and NaNO2, the inhibition of AOR and NOR by KMPS on AOR and NOR was weakened after the second and third dosing times. That is, AOR and NOR can recover partially or completely over time. The L. vannamei aquaculture experiment was performed using four concentrations of KMPS (0, 2, 4 and 8 mg/L). The results showed that with increasing KMPS dosage, the average and peak concentrations of NH4+-N and NO2--N in each treatment significantly increased (P < 0.05), and the final body weight of shrimp significantly decreased (P < 0.05). Furthermore the highest dose (8.0 mg/L) of KMPS reduced the survival rate by 9.33% compared to the CK. High-throughput sequencing analysis of the biofilm structure showed that the relative abundances of Nitrospirota, Nitrosomonas and Nitrococcus, which are related to nitrogen cycling, and beneficial bacteria including Firmicutes and Bacilli decreased with the addition of KMPS (p < 0.05).

Advances in 2D Materials Based Gas Sensors for Industrial Machine Olfactory Applications

The escalating development and improvement of gas sensing ability in industrial equipment, or "machine olfactory", propels the evolution of gas sensors toward enhanced sensitivity, selectivity, stability, power efficiency, cost-effectiveness, and longevity. Two-dimensional (2D) materials, distinguished by their atomic-thin profile, expansive specific surface area, remarkable mechanical strength, and surface tunability, hold significant potential for addressing the intricate challenges in gas sensing. However, a comprehensive review of 2D materials-based gas sensors for specific industrial applications is absent. This review delves into the recent advances in this field and highlights the potential applications in industrial machine olfaction. The main content encompasses industrial scenario characteristics, fundamental classification, enhancement methods, underlying mechanisms, and diverse gas sensing applications. Additionally, the challenges associated with transitioning 2D material gas sensors from laboratory development to industrialization and commercialization are addressed, and future-looking viewpoints on the evolution of next-generation intelligent gas sensory systems in the industrial sector are prospected.

Comparative Microbiome Analysis of Artemia spp. and Potential Role of Microbiota in Cyst Hatching

Brine shrimp (Artemia spp.) is a significant factor in determining aquaculture production. Since the microbiota of Artemia can colonize the gut in larvae, various microorganisms transmitted from Artemia can affect host larval health. Although the microbiota composition of Artemia would be essential in determining aquaculture productivity, our understanding on microbiome of Artemia is still insufficient. Through our study, we identified the species of Artemia cysts supplied by three different manufacturers (P1, P2, and P3) with investigation of size and hatching efficiency. The species of Artemia from P1 was identified as A. tibetiana, and P2 and P3 was A. franciscana. A. tibetiana hatched from the P1 cysts had the largest body size with the lowest hatching rate. Furthermore, we conducted a comprehensive analysis of the microbiome present in the rearing water and the nauplius whole body from each product. We observed specific microbiota compositions, both beneficial and harmful, depending on the product types and the sample types. Additionally, we found that the microbiota composition in the rearing water was associated with the manufacturing environment, while the compositions in the nauplius whole body were species-specific. Notably, we discovered that an extract containing microbiota from the nauplius sample of P3 increased the hatching rate of A. tibetiana, indicating a positive role in Artemia culture. These findings demonstrate that the microbial communities present in Artemia vary according to the product and/or species, underscoring their significance in aquaculture production.

Assessing the efficacy of bleaching powder in disinfecting marine water: Insights from the rapid recovery of microbiomes

Single-bleaching powder disinfection is a highly prevalent practice to disinfect source water for marine aquaculture to prevent diseases. However, due to the decay of active chlorine and the presence of disinfectant resistance bacteria (DRB), the effects of bleaching powder on prokaryotic community compositions (PCCs) and function in marine water remain unknown. In the present study, the source water in a canvas pond was treated with the normal dose of bleaching powder, and the impact on PCCs and functional profiles was investigated using 16S rRNA gene amplicon sequencing. The bleaching powder strongly altered the PCCs within 0.5 h, but they began to recover at 16 h, eventually achieving 76% similarity with the initial time at 72 h. This extremely rapid recovery was primarily driven by the decay of Bacillus and the regrowth of Pseudoalteromonas, both of which are DRB. Abundant community not only help PCCs recover but also provide larger functional redundancy than rare community. During the recovery of PCCs, stochastic processes drove the community assembly. After 72 h, five out of seven identified disinfectant resistance genes related to efflux pump systems were highly enriched, primarily in Staphylococcus and Bacillus. However, 15 out of the 16 identified antibiotic resistance genes (ARGs) remained unchanged compared to the initial time, indicating that bleaching powder does not contribute to ARGs removal. Overall, the findings demonstrate that single-bleaching powder disinfection cannot successfully meet the objective of disease prevention in marine aquaculture water due to the extremely rapid recovery of PCCs. Hence, secondary disinfection or novel disinfection strategies should be explored for source water disinfection.