Performance and dynamic characteristics of microbial communities in multi-stage anaerobic reactors treating gibberellin wastewater

Dietary supplementation with Dendrobium officinale leaves improves growth, antioxidant status, immune function, and gut health in broilers

Background

The Dendrobium officinale leaves (DOL) is an underutilized by-product with a large biomass, which have been shown to exhibit immunomodulatory and antioxidant functions. The purpose of this research was to investigate the effects of DOL on broiler growth performance, antioxidant status, immune function, and gut health.

Methods

One hundred and ninety-two 1-day-old chicks were selected and divided into 4 groups at random, 6 replicates for each group and 8 in each. Chicks were given a basal diet supplemented with different amounts of DOL: 0% (control group, NC), 1% (LD), 5% (MD), or 10% (HD). During the feeding trial (70 days), broiler body weight, feed intake, and residual feeding were recorded. On d 70, 12 broilers from each group were sampled for serum antioxidant and immune indexes measurement, intestinal morphological analysis, as well as 16S rRNA sequencing of cecal contents and short-chain fatty acid (SCFA) determination.

Results

In comparison to the NC group, the LD group had greater final body weight and average daily gain, and a lower feed conversion ratio (p < 0.05, d 1 to 70). However, in MD group, no significant change of growth performance occurred (p > 0.05). Furthermore, DOL supplementation significantly improved the levels of serum total antioxidant capacity, glutathione peroxidase, superoxide dismutase, and catalase, but reduced the level of malondialdehyde (p < 0.05). Higher serum immunoglobulin A (IgA) content and lower cytokine interleukin-2 (IL-2) and IL-6 contents were observed in DOL-fed broilers than in control chickens (p <0.05). Compared to the NC group, duodenal villus height (VH) and villus height-to-crypt depth (VH:CD) ratio were considerably higher in three DOL supplementation groups (p < 0.05). Further, 16S rRNA sequencing analysis revealed that DOL increased the diversity and the relative abundance of cecal bacteria, particularly helpful microbes like Faecalibacterium, Lactobacillus, and Oscillospira, which improved the production of SCFA in cecal content. According to Spearman correlation analysis, the increased butyric acid and acetic acid concentrations were positively related to serum antioxidant enzyme activities (T-AOC and GSH-Px) and immunoglobulin M (IgM) level (p < 0.05).

Conclusion

Overall, the current study demonstrated that supplementing the dies with DOL in appropriate doses could enhance growth performance, antioxidant capacity, and immune response, as well as gut health by promoting intestinal integrity and modulating the cecal microbiota in broilers. Our research may serve as a preliminary foundation for the future development and application of DOL as feed additive in broiler chicken diets.

Effects of Fenugreek Seed Extracts on Growth Performance and Intestinal Health of Broilers

The purpose of this experiment was to study the effects of fenugreek seed extract (FSE) on the growth performance, intestinal morphology, intestinal immunity and cecal micro-organisms in yellow-feathered broilers. A total of 240 one-day-old male yellow-feathered broilers were selected and randomly assigned to four treatments with 6 replicates per group and ten broilers per replicate. Started from the third day, birds were fed with basal diet (CON group) or basal diet supplemented with 30 mg/kg Zinc bacitracin (ZB group), or basal diet supplemented with 50 (D-FSE group) or 100 (H-FSE group) mg/kg FSE, respectively. The experiment lasted for 56 d. The results showed that dietary FSE supplementation improved average daily weight gain (ADG) and ratio of feed to weight gain (F: G) (P < 0.01), increased intestinal villus height (VH), villus height to crypt depth ratio (V/C) (P < 0.05), serum concentrations of IL-10, and the contents of secretory immunoglobulin A (sIgA) (P < 0.05), as well as decreased the activity of iNOS (P < 0.05). The high-throughput sequencing results showed that dietary FSE supplementation increased the alpha diversity of cecal microbes, and Firmicutes, Bacteroidetes, Verrucomicrobia and Proteobacteria taken up 95% of all phyla detected, FSE significantly reduced Campylobacter, Synergistes, and Lachnoclostridium abundance (P ≤ 0.05). There were significant difference in more than 30 KEGG pathways between FSE added group and control group or ZB group. FSE supplementation, in other words, maintained gut microbiota homeostasis while improving broiler growth performance. As a result, FSE has the potential to replace prophylactic antibiotic use in poultry production system.

Influence of cosubstrate and hydraulic retention time on the removal of drugs and hygiene products in sanitary sewage in an anaerobic Expanded Granular Sludge Bed reactor

Diclofenac (DCF), ibuprofen (IBU), propranolol (PRO), triclosan (TCS) and linear alkylbenzene sulfonate (LAS) can be recalcitrant in Wastewater Treatment Plants (WWTP). The removal of these compounds was investigated in scale-up (69 L) Expanded Granular Sludge Bed (EGSB) reactor, fed with sanitary sewage from the São Carlos-SP (Brazil) WWTP and 200 mg L^-1 of ethanol. The EGSB was operated in three phases: (I) hydraulic retention time (HRT) of 36±4 h; (II) HRT of 20±2 h and (III) HRT of 20±2 h with ethanol. Phases I and II showed no significant difference in the removal of LAS (63 ± 11-65 ± 12 %), DCF (37 ± 18-35 ± 11 %), IBU (43 ± 18-44 ± 16 %) and PRO (46 ± 25-51 ± 23 %) for 13±2-15 ± 2 mg L^-1, 106 ± 32-462 ± 294 μg L^-1, 166 ± 55-462 ± 213 μg L^-1 and 201 ± 113-250 ± 141 μg L^-1 influent, respectively. Higher TCS removal was obtained in phase I (72 ± 17 % for 127 ± 120 μg L^-1 influent) when compared to phase II (51 ± 13 % for 135 ± 119 μg L^-1 influent). This was due to its greater adsorption (40 %) in the initial phase. Phase III had higher removal of DCF (42 ± 10 % for 107 ± 26 μg L^-1 influent), IBU (50 ± 15 % for 164 ± 47 μg L^-1 influent) and TCS (85 ± 15 % for 185 ± 148 μg L^-1 influent) and lower removal of LAS (35 ± 14 % for 12 ± 3 mg L^-1 influent) and PRO (-142 ± 177 % for 188 ± 88 μg L^-1 influent). Bacteria similar to Syntrophobacter, Smithella, Macellibacteroides, Syntrophus, Blvii28_wastewater-sludge_group and Bacteroides were identified in phase I with relative abundance of 3.1 %-4.7 %. Syntrophobacter was more abundant (15.4 %) in phase II, while in phase III, it was Smithella (12.7 %) and Caldisericum (15.1 %). Regarding the Archaea Domain, Methanosaeta was more abundant in phases I (84 %) and II (67 %), while in phase III it was Methanobacterium (86 %).

Substrate competition and microbial function in sulfate-reducing internal circulation anaerobic reactor in the presence of nitrate

Nitrate and sulfate often coexist in organic wastewater. In this study, an internal circulation anaerobic reactor was conducted to investigate the impact of nitrate on sulfate reduction. The results showed that sulfate reduction rate dropped from 78.4% to 41.4% at NO₃^- /SO₄^2- ratios ranging from 0 to 1.03, largely attributed to the inactivity of acetate-utilizing sulfate-reducing bacteria (SRB) and preferential usage of nitrate of propionate-utilizing SRB. Meanwhile, high nitrate removal efficiency was maintained and COD removal efficiency increased with nitrate addition. Enhancement of propionate and butyrate degradation based on Modified Gompertz model and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2) analysis. Moreover, nitrate triggered the shift of microbial community and function. Twelve genera affiliated to Firmicutes, Bacteroidetes and Proteobacteria were identified as keystone genera via network analysis, which kept functional stability of the bacterial community responding to nitrate stress. Increased nitrate inhibited Desulfovibrio, but promoted the growth of Desulforhabdus. Both the predicted functional genes associated with assimilatory sulfate reduction pathway (cysC and cysNC) and dissimilatory sulfate reduction pathway (aprA, aprB, dsrA and dsrB) exhibited negative relationship with nitrate addition.

Influence of metabolic cosubstrates on methanogenic potential and degradation of triclosan and propranolol in sanitary sewage

Triclosan (TCS) and propranolol (PRO) are emerging micropollutants that are difficult to remove in wastewater treatment plants. In this study, methanogenic potential (P) of anaerobic sludge submitted to TCS (3.6 ± 0.1 to 15.5 ± 0.1 mg L^-1) and PRO (6.1 ± 0.1 to 55.9 ± 1.2 mg L^-1) in sanitary sewage, was investigated in batch reactors. The use of cosubstrates (200 mg L^-1 of organic matter) ethanol, methanol:ethanol and fumarate was evaluated for micropollutant degradation. Without cosubstrates, P values for 5.0 ± 0.1 mgTCS L^-1, 15.5 ± 0.1 mgTCS L^-1 and 55.0 ± 1.3 mgPRO L^-1 were 50.53%, 98.24% and 17.66% lower in relation to Control assay (855 ± 5 μmolCH4) with sanitary sewage, without micropollutants and cosubstrates, respectively. The use of fumarate, ethanol and methanol:ethanol favored greater methane production, with P values of 2144 ± 45 μmolCH₄, 2960 ± 185 μmolCH₄ and 2239 ± 171 μmolCH₄ for 5.1 ± 0.1 mgTCS L^-1, respectively; and of 10,827 ± 185 μmolCH₄, 10,946 ± 108 μmolCH₄ and 10,809 ± 210 μmolCH₄ for 55.0 ± 1.3 mgPRO L^-1, respectively. Greater degradation of TCS (77.1 ± 0.1% for 5.1 ± 0.1 mg L^-1) and PRO (24.1 ± 0.1% for 55.9 ± 1.2 mg L^-1) was obtained with ethanol. However, with 28.5 ± 0.5 mg PRO L^-1, greater degradation (88.4 ± 0.9%) was obtained without cosubstrates. With TCS, via sequencing of rRNA 16S gene, for Bacteria Domain, greater abundance of phylum Chloroflexi and of the genera Longilinea, Arcobacter, Mesotoga and Sulfuricurvum were identified. With PRO, the genus VadinBC27 was the most abundant. Methanosaeta was dominant in TCS with ethanol, while in PRO without cosubstrates, Methanobacterium and Methanosaeta were the most abundant. The use of metabolic cosubstrates is a favorable strategy to obtain greater methanogenic potential and degradation of TCS and PRO.

Bacterial community composition of internal circulation reactor at different heights for large-scale brewery wastewater treatment

This study analyzed bacterial community structure for large-scale brewery wastewater treatment at different heights in internal circulation (IC) reactor. Proteobacteria, Bacteroidetes and Chloroflexi were dominant bacteria, which accounted for 64.17%, 64.04%, 59.87% and 55.79% in phylum level, respectively. The unidentified bacteria were accounted for a large proportion in genus level, available data showed that Longilinea, Desulfomicrobium, Caldithrix, Geobacter and Syntrophorhabdus were relatively abundant. Organic fermentation, hydrolysis, and acidification were mainly completed at the bottom, and production of hydrogen and methane were completed in the upper and middle part of reactor. Alpha diversity and cluster distance analysis showed the bacterial community could be divided into bottom, middle and upper part of IC reactor. The IC reactor possessed the COD_Cr removal efficiency of 80% - 84.09%, and BOD₅ of 77.50% - 86% for brewery wastewater. This study would provide bacterial analysis references of IC reactor for industrial wastewater treatment in future.

Archaeal and bacterial community structures of rural household biogas digesters with different raw materials in Qinghai Plateau

The present study aims to investigate microbial community structures household biogas digesters with different raw materials in Qinghai Plateau rural. High-throughput 16S rRNA gene sequencing analysis revealed that Firmicutes, Bacteroidetes, and Proteobacteria are the most abundant bacterial phyla (64.08%). Prevotella group 7 was the most abundant genus in digester YL9 and YL10 (69.72% and 26.96%, respectively) using vegetable waste raw materials. Trichococcus exhibited the highest abundance (14.55%) in YL1 digester using sheep and pig manure. Clostridium sensu stricto 1 (13.89%) and Synergistaceae_uncultured (15.52%) comprised the highest abundances in digester YL5 with mixed raw materials (i.e., dairy manure, sheep manure, and human feces). In addition, Proteiniphilum and Pseudomonas exhibited the highest abundances among bacterial genera in YL4 digester using pig manure. Methanomicrobiales was the most dominant archaeal communities, ranging from 13.35% to 81.34% in abundance. Methanocorpusculum exhibited dominant abundances in all digesters using various raw materials. Methanogenium was the most abundant archaeal genera in YL4 and YL6 digesters, which consume pig manure as primary raw material. In addition, Methanosarcina and Methanosaeta exhibited the highest abundances in digester YL1 (55.03%) and YL9 (51.40%), respectively. Moreover, fermentation temperatures and pH both contributed to the archaeal and bacterial community structures in all the investigated digesters. Specially, fermentation temperature showed positive correlation with the abundances of Synergistaceae_uncultured, Methanogenium, and Methanosaeta, and pH was positively correlated with the abundances of Prevotella group 7 and Methanosarcina abundances.

Principal component analysis as a criterion for monitoring variable organic load of swine wastewater in integrated biological reactors UASB, SABF and HSSF-CW

The multivariate analysis to optimize the parameters of wastewater is essential to reduce costs. The aim of this study was to evaluate the use of multivariate and conventional analysis in biological system composed by upflow anaerobic sludge blanket (UASB), submerged aerated biological filters (SABF) and horizontal subsurface flow constructed wetland (HSSF-CW) reactors in the organic stabilization of swine wastewater (SW). Four loads were used in the system with alteration by COD concentration of untreated SW, and the data were evaluated by principal components (PCA). The average efficiency of COD and BOD removal increased from 45% in phase I to 67% in phase IV in the UASB, SABF and HSSF-CW reactors. The principal component analysis promoted the reduction of 13 original variables to 5, 8 and 5 principal components in the UASB, SABF and HSSF-CW reactors, respectively, optimizing the dynamics of interpretation of the data that influenced the most the stability of the wastewater system across the four phases. There was a strong negative effect of oxygen concentrations in the SABF reactor in relation to organic variables, optimizing the biological mechanisms of the HSSF-CW and, therefore, enabling better decision making and cost reduction with analysis at treatment plants.

Nitrogen removal mechanism and microbial community changes of bioaugmentation subsurface wastewater infiltration system

Limited nitrogen removal capacity (mainly nitrate, NO₃^--N) remains a major challenge for subsurface wastewater infiltration system (SWIS). Two nitrogen-removing strains have been isolated from SWIS and inoculated to SWIS to investigate the effect of bioaugmentation on nitrogen removal performance and mechanism. The results showed bioaugmentation improved the removal efficiencies of NH₄⁺-N from 86.81% to 92.86% and TN from 74.90% to 86.55% and running stability compared to unbioaugmentation SWIS. 16 s rRNA amplicon sequencing results of the bacterial indicated that bioaugmentation altered the microbial community structure especially at 150 cm depth and increased the relative abundance of bacteria associated with nitrogen removal, significantly increasing the abundance of Rhizobiales_Incertae_Sedis and Lachnospiraceae. Furthermore, the relation between internal microbial characteristics and operational factors indicated that Hyphomicrobiaceae and Gemmatimonadaceae were also closely related to nitrogen removal. Predicted function profiles revealed that bioaugmentation enhanced the activity of nitrogen removal enzymes (Hao, NorBC, NasAB, NarGHI, NirBD and NosZ).