bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.11.24.568540

Nitrite deteriorates bioreactor performance by reducing growth of Ca. Brocadia sapporoensis instead of inhibiting the anammox activity

Qiao, X.·Zhang, L.·Wu, Y.·Deng, C.·Zhang, Y.·Zhang, X.·Yan, Y.·Zhuang, W.·Yu, K.
View original source ↗Export metadata ↓

Abstract

Effects of nitrite on anammox activities have been of widespread concern. However, the molecular mechanisms of specific microorganisms in anammox systems responding to nitrite remain unexplored. This study investigated the effects of excess nitrite on core metabolism of AnAOB and symbiotic bacteria, and further elucidated the response mechanism of these effects on microbial growth and nitrogen removal performance. Specifically, nitrogen removal process in a continuous-flow anaerobic ammonia oxidation membrane bioreactor completely collapsed when the nitrite concentration reached 243 mg N/L. Integrated meta-omics analyses demonstrated that excess nitrite disrupted the energy metabolism of Ca. Brocadia sapporoensis (AMXB1), reducing the energy available for establishing tolerance. It disrupted cell replication by impairing biosynthesis process of AMXB1, especially DNA replication and the formation of vital cell structures, e.g., cell membrane and cell wall, as well as the cellular protection system, leading to the collapse of the anammox system. In addition, the cross-feeding of glycogen, lipopolysaccharide and amino acid between AMXB1 and symbiotic bacteria was hindered by excess nitrite, which also contributed to the anomalous cell proliferation and metabolism of AMXB1. These findings contribute to our understanding of the ability of anammox consortia to respond to nitrite stress and process stability in engineered ecosystems. HighlightsO_LINO --N concentration of 243 mg N/L caused the performance collapse of a continuous-flow anammox MBR. C_LIO_LIExcess nitrite likely disrupted the energy metabolism of AMXB1, reducing the energy availability for mitigating nitrite toxicity. C_LIO_LIThe cross-feeding between AMXB1 and symbiotic bacteria was hindered by excess nitrite. C_LIO_LIThe hindrance of cross-feeding was reversed as the concentration of nitrite decreased. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/568540v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@6b199forg.highwire.dtl.DTLVardef@15f2a74org.highwire.dtl.DTLVardef@dc2d8eorg.highwire.dtl.DTLVardef@132deb1_HPS_FORMAT_FIGEXP M_FIG C_FIG

Explore related subjects

bioengineeringPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Qiao, X., Zhang, L., Wu, Y., Deng, C., Zhang, Y., Zhang, X., Yan, Y., Zhuang, W., Yu, K.. 2023-11-24. Nitrite deteriorates bioreactor performance by reducing growth of Ca. Brocadia sapporoensis instead of inhibiting the anammox activity. https://doi.org/10.1101/2023.11.24.568540

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Wall stiffening is a primary contributor to motility loss in Crohn's disease: an electromechanical modeling study

Fibrotic strictures are among the most disabling complications of Crohn's disease, permanently narrowing the bowel and impairing motility, yet no approved therapy reverses them. Chronic inflammation alters pacemaker-network coupling, smooth-muscle excitability, and calcium-dependent contractility, while fibrosis thickens the bowel wall, narrows the lumen, and changes tissue mechanics. The relative contributions of these coupled electrical, contractile, and structural alterations to motility loss remain unclear. To address this gap, we develop an integrated electromechanical finite-element framework for fibrostenosing Crohn's disease that couples a fibrosis-driven growth model with a FitzHugh-Nagumo electromechanical model. A full-factorial 25 design of experiments is used to quantify the relative effects of electrical diffusivity, excitation threshold, peak active stress, wall stiffness, and hypertrophic remodeling on cyclic lumen-volume deformation. Motility is quantified by the standard deviation of lumen volume over one contraction cycle. Within the parameter ranges examined, increased wall stiffness emerged as the dominant contributor to motility loss, followed by impaired smooth-muscle contractility. Changes in excitation threshold, hypertrophic remodeling, and electrical diffusivity produced substantially smaller effects. Pairwise interactions were small relative to the dominant main effects, indicating that the mechanisms contributed largely through their individual effects. Our findings suggest that limiting wall stiffening while preserving smooth-muscle contractile function may provide a therapeutic strategy for maintaining intestinal motility in fibrostenosing Crohn's disease.

bioengineering↗
bioRxiv2026

Lactate Receptor Activation Alleviates Senescence and Preserves Homeostasis of Aged Arteries

Arteries are among the first tissues to exhibit age-related dysfunction, yet the metabolic mechanisms driving vascular senescence remain poorly understood. Here, analysis of human aortic transcriptomic data identified HCAR1, encoding the lactate receptor GPR81, as one of the genes most significantly downregulated with age. We therefore investigated whether age-associated loss of GPR81 contributes to cellular senescence within the vessel wall. Senescent human endothelial cells and vascular smooth muscle cells accumulated neutral and oxidized lipids and exhibited increased labile iron and ferroptosis. Silencing GPR81 in early-passage cells recapitulated this metabolic phenotype together with multiple hallmarks of cellular senescence. Moreover, endothelial-specific deletion of GPR81 in young mice was sufficient to induce senescent cell accumulation, impaired lipid homeostasis, endothelial dysfunction, and elastin disorganization. Conversely, pharmacological activation of GPR81 with the agonist CHBA restored fatty acid metabolism, promoted glycolytic reprogramming, and attenuated ferroptotic stress and senescence-associated phenotypes. In lamin A knock-in (LAKI) progeroid mice, CHBA reduced arterial lipid accumulation and cellular senescence, shifted vascular cell composition toward a youthful state, improved endothelial integrity, and restored extracellular matrix homeostasis. Together, these findings identify age-associated loss of GPR81 as a driver of vascular metabolic dysfunction and cellular senescence and establish pharmacological GPR81 activation as a promising therapeutic strategy for preserving vascular homeostasis and mitigating age-associated cardiovascular disease.

bioengineering↗
bioRxiv2026

Targeted and bilateral blood flow monitoring in middle cerebral artery using diffuse correlation spectroscopy

Objective: To develop and validate a dual-probe Diffuse Correlation Spectroscopy (DCS) system for non-invasive and simultaneous, monitoring of cerebral blood flow (CBF) in the bilateral Middle Cerebral Artery (MCA) territories, and expanding the utility of conventional DCS limited to cortical-volume-based CBF measurements to vessel-specific cerebral perfusion monitoring. Methods: A dual-probe DCS system was designed for non-invasive monitoring of MCA-specific perfusion. Probe placement and protocol optimization study has been performed using anatomical landmarks, motor and speech activation tasks in healthy volunteers. System stability and repeatability were further evaluated in a pilot cohort of 30 healthy (age, 25{+/-}7 years) participants using optimized probe position and protocol. A bilateral MCA ischemic Lacunar Infract stroke case report also validated the feasibility of the system in clinical settings. Results: Measurements demonstrated superior sensitivity towards MCA-territory perfusion at targeted probe locations compared to off-MCA positions. In pilot cohort, significant increase of 30.34 {+/-} 21.56% and 36.48 {+/-} 21.22% in rCBF corresponding to hand squeeze and speech task respectively showed reproducible physiological responsiveness of the system (p<0.001). Measurement done on a patient with bilateral MCA ischemic Lacunar Infract stroke showed a significant change of 30% during speech for both the MCAs but no significant change is observed for hand squeeze tasks. Conclusion: The custom built dual-probe DCS system enables non-invasive, operator-independent, targeted and continuous monitoring of rCBF within bilateral MCA territories. Significance: This approach enables the potential use of DCS system for bilateral and vessel-specific monitoring of cerebral perfusion in the MCA territories.

bioengineering↗