Emerging Function of Ecotype-Specific Splicing in the Recruitment of Commensal Microbiome.

In recent years, host-microbiome interactions in both animals and plants has emerged as a novel research area for studying the relationship between host organisms and their commensal microbial communities. The fitness advantages of this mutualistic interaction can be found in both plant hosts and their associated microbiome, however, the driving forces mediating this beneficial interaction are poorly understood. Alternative splicing (AS), a pivotal post-transcriptional mechanism, has been demonstrated to play a crucial role in plant development and stress responses among diverse plant ecotypes. This natural variation of plants also has an impact on their commensal microbiome. In this article, we review the current progress of plant natural variation on their microbiome community, and discuss knowledge gaps between AS regulation of plants in response to their intimately related microbiota. Through the impact of this article, an avenue could be established to study the biological mechanism of naturally varied splicing isoforms on plant-associated microbiome assembly.

[Formation Mechanism of Aerobic Granular Sludge and Removal Efficiencies in Integrated ABR-CSTR Reactor].

Anaerobic Baffled Reactor (ABR) was altered to make an integrated anaerobic-aerobic reactor. The research investigated the mechanism of aerobic sludge granulation, under the condition of continuous-flow. The last two compartments of the ABR were altered into aeration tank and sedimentation tank respectively with seeded sludge of anaerobic granular sludge in anaerobic zone and conventional activated sludge in aerobic zone. The HRT was gradually decreased in sedimentation tank from 2.0 h to 0.75 h and organic loading rate was increased from 1.5 kg x (M3 x d)(-1) to 2.0 kg x (M3 x d)(-1) while the C/N of 2 was controlled in aerobic zone. When the system operated for 110 days, the mature granular sludge in aerobic zone were characterized by compact structure, excellent sedimentation performance (average sedimentation rate was 20.8 m x h(-1)) and slight yellow color. The system performed well in nitrogen and phosphorus removal under the conditions of setting time of 0.75 h and organic loading rate of 2.0 kg (m3 x d)(-1) in aerobic zone, the removal efficiencies of COD, NH4+ -N, TP and TN were 90%, 80%, 65% and 45%, respectively. The results showed that the increasing selection pressure and the high organic loading rate were the main propulsions of the aerobic sludge granulation.

[Start-up Performance of ANAMMOX Enrichment with Different Inoculated Sludge in Anaerobic Baffled Reactor].

Two anaerobic baffled reactors (ABR) were compared for anaerobic ammonium oxidation (ANAMMOX) enrichment using synthetic wastewater with different inoculated sludge, the mixed anaerobic flocculent sludge/granular sludge (R1) and anaerobic activated sludge (R2). The research showed the ANAMMOX activity occurred in both reactors allowing continuous removal of ammonium and nitrite, in which the ammonia and nitrite nitrogen loading was about 54.5-68.0 g (m3 x d)(-1), when maintaining the temperature at 30-35 degrees C, pH at 7.5 +/- 0.5 and HRT at 26 h. However, the ANAMMOX reaction was successfully started after 120 d and 125 d, respectively. The removal rules of the two reactors were basically similar, and the enrichment processes occurred in both reactors could be divided into 4 phases, which were sluggish phase, expressive phase, enhanced phase and steady phase. In the steady phase, the average removal rates of NH4+ -N, NO2- -N were higher than 90%, and the average removal load achieved 57.3-67.9 g x (m3 x d)(-1). Moreover, the ammonium removal load in R1 was slightly higher than that in R2. Additionally, more than 90% of nitrogen was dramatically removed in the first compartment of ABR. Meanwhile, the color of sludge gradually changed from brown, litter bed brown to black along with the flow direction, which was similar to the removal rule of nitrogen. In a word, the results showed the different inoculated sludge did not cause obvious differences in the starting rule and the removal characteristics of ANAMMOX reactor.

[Research on Cultivation and Stability of Nitritation Granular Sludge in Integrated ABR-CSTR Reactor].

Abstract: The last two compartments of the Anaerobic Baffled Readtor ( ABR) were altered into aeration tank and sedimentation tank respectively to get an integrated anaerobic-aerobic reactor, using anaerobic granular sludge in anaerobic zone and aerobic granular sludge in aerobic zone as seed sludge. The research explored the condition to cultivate nitritation granular sludge, under the condition of continuous flow. The C/N rate was decreased from 1 to 0.4 and the ammonia nitrogen volumetric loading rate was increased from 0.89 kg x ( m3 x d)(-1) to 2.23 kg x (m3 x d)(-1) while the setting time of 1 h was controlled in the aerobic zone. After the system was operated for 45 days, the mature nitritation granular sludge in aerobic zone showed a compact structure and yellow color while the nitrite accumulation rate was about 80% in the effluent. The associated inhibition of free ammonia (FA) and free nitrous acid (FNA) dominated the nitritation. Part of granules lost stability during the initial period of operation and flocs appeared in the aerobic zone. However, the flocs were transformed into newly generated small particles in the following reactor operation, demonstrating that organic carbon was benefit to granulation and the enrichment of slow-growing nitrifying played an important role in the stability of granules.