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The indoor recirculating aquaculture system (RAS) is a sustainable alternative to traditional aquaculture systems, and a biofilter is a crucial component for the stable operation of this system. In this study, the bacterial communities within different sections of the biofilter in a full‐scale RAS for the culture of Tongue Sole Cynoglossus semilaevis were investigated using polymerase chain reaction–based 454 pyrosequencing. A total of 67,368 effective sequences of the 16S rRNA gene with V1–V3 regions were obtained from samples collected from the front section, rear section, and sludge of the biofilter. Using a 3% cut‐off level and sufficient sequencing depth, a total of 5,185 operational taxonomic units (OTUs) were identified in these sequences across all samples. However, a low shared richness of 570 OTUs (11.0% of the reads) was found in all samples, indicating a high diversity of bacterial profiles even in a single biofilter. Based on the SILVA database classifier of phylogenetic taxa, Proteobacteria (average, 35.6%) and Bacteroidetes (average, 30.7%) were found to be the predominant species in all samples, followed by Nitrospirae (6.0%) in the front section, Acidobacteria (7.9%) in the rear section, and Planctomycetes (9.7%) in the sludge. Overall, 404 genera were assigned to all samples. But among the 10 most common genera, only Nitrospira, Owenweeksia, and Marinicella were found in all samples. The results of the phylogenetic analysis suggest that the nitrifying groups of ammonia‐oxidizing bacteria belong to Nitrosomonas clusters, and the nitrite‐oxidizing bacteria are related to Nitrospira and Nitrospina clusters. In summary, our results indicate that the RAS fixed‐film biofilter is a highly species‐rich ecosystem. For this reason, a potential precision‐operated strategy to manage the microbial resources in the biological treatment section in an RAS should be adopted, with consideration being given to the peculiarities and requirements of the species being cultured.

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Objective The study was conducted to evaluate the effects of night light regimen on growth performance, antioxidant status and health of Lingnan Yellow broiler chickens from 1 to 21 days of age. Methods A completely randomized factorial design involved 2 photoperiods (constant lighting [CL], 24 L:0 D and intermittent lighting [INL], 17 L:3 D:1 L:3 D)×2 light intensities (10 lx and 30 lx). A total of one thousand six hundred and eighty 1-d-old Lingnan Yellow broiler chicks were randomly divided into 4 treatments with 6 replicates (70 birds per replicate). The experiment lasted for 21 d. Results Photoperiods and light intensities had no effect on average daily gain, feed conversion ratio, and mortality of the broiler chickens (p>0.05). The INL had a significant effect on average daily feed intake (p<0.05) of broiler chickens compared with CL. Photoperiod and light intensity had an interactive effect on melatonin (MT) concentration (p<0.05). At CL, reducing light intensity increased MT concentration; INL birds had higher MT but MT concentration was not affected by light intensity. There was an interactive effect on glutathione peroxidase (GPx) and catalase (CAT) in serum and total antioxidant capability (T-AOC) in liver between photoperiod and light intensity. With the decrease of light intensity, the activities of GPx and CAT in serum and T-AOC in liver increased in CL group (p<0.05). Broiler chickens reared under INL had better antioxidant status and 10 lx treatments had higher activities of CAT in serum than 30 lx (p<0.05). Different photoperiods and light intensities had no effect on malondialdehyde. There was an interaction between photoperiod and light intensity on serum creatine kinase (CK) concentration (p<0.05). At CL, the elevated light intensity resulted in an increase in CK content; INL birds had lower CK concentration especially in low light intensity group. Besides, INL and low light intensity significantly reduced the concentration of serum corticosterone and heat shock protein 70 (p<0.05). Serum immunoglobulin M contents were increased in broiler chickens reared under the INL compared with CL group (p<0.05). Conclusion Results above suggest that the night light regimen of INL and 10 lx could be beneficial to the broiler chickens from 1 to 21 days of age due to the better health status and electricity savings.

The interactions between environmental factors and bacterial community shift in solid-phase denitrification are crucial for optimum operation of a reactor and to achieve maximum treatment efficiency. In this study, Illumina high-throughput sequencing was applied to reveal the effects of different operational conditions on bacterial community distribution of three continuous operated poly(butylene succinate) biological denitrification reactors used for recirculating aquaculture system (RAS) wastewater treatment. The results indicated that salinity decreased OTU numbers and diversity while dissolved oxygen (DO) had no obvious influence on OTU numbers. Significant microbial community composition differences were observed among and between three denitrification reactors under varied operation conditions. This result was also demonstrated by cluster analysis (CA) and detrended correspondence analysis (DCA). Hierarchical clustering and redundancy analysis (RDA) was performed to test the relationship between environmental factors and bacterial community compositions and result indicated that salinity, DO and hydraulic retention time (HRT) were the three key factors in microbial community formation. Besides, Simplicispira was detected under all operational conditions, which worth drawing more attention for nitrate removal. Moreover, the abundance of nosZ gene and 16S rRNA were analyzed by real-time PCR, which suggested that salinity decreased the proportion of denitrifiers among whole bacterial community while DO had little influence on marine reactors. This study provides an overview of microbial community shift dynamics in solid-phase denitrification reactors when operation parameters changed and proved the feasibility to apply interval aeration for denitrification process based on microbial level, which may shed light on improving the performance of RAS treatment units.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-017-0412-3) contains supplementary material, which is available to authorized users.

Physiological mechano-acoustic signals play a pivotal role in medical diagnosis and fitness monitoring. Mechanical waves generated by natural physiological activities such as myocardial contraction, and vocal fold vibration, propagate through the tissues and fluids of the body and reveal characteristic signals of these events. Conventional methods such as stethoscope and electrocardiography (ECG) are not suitable for wearable mode and continuous monitoring. In this paper, we propose a wearable physiological sounds sensing device to monitor heart sound and detect speech and voice with high accuracy. The device consists of a MEMS (microelectromechanical systems) acoustic sensor and a low-noise amplification circuit, and both of them are packaged by silicone polymers with an air cavity to achieve conformal contact with human skin. The proposed device has advantages of light weight, sweatproof capability, resistant to noise and good stability. The wearable device has great potential in clinical diagnosis, healthcare, human-machine interaction and many other applications.