Metagenomic analysis of relationships between the denitrification process and carbon metabolism in a bioaugmented full-scale tannery wastewater treatment plant
WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
Authors: Emmanuel, S. Aalfin; Sul, Woo Jun; Seong, Hoon Je; Rhee, Chaeyoung; Ekpheghere, Kalu, I; Kim, In-Soo; Kim, Hong-Gi; Koh, Sung-Cheol
Abstract
The goal of this study was to investigate the relationship between the denitrification process and carbon metabolism in a full-scale tannery wastewater treatment plant bioaugmented with the microbial consortium BM-S-1. The metagenomic analysis of the microbial community showed that Brachymonas denitrificans, a known denitrifier, was present at a high level in the treatment stages of buffering (B), primary aeration (PA), and sludge digestion (SD). The occurrences of the amino acid-degrading enzymes alpha ketoglutarate dehydrogenase (alpha-KGDH) and tryptophan synthase were highly correlated with the presence of denitrification genes, such as napA, narG, nosZ and norB. The occurrence of glutamate dehydrogenase (GDH) was also highly paralleled with the occurrence of denitrification genes such as napA, narG, and norZ. The denitrification genes (nosZ, narG, napA, norB and nrfA) and amino acid degradation enzymes (tryptophan synthase, alpha-KGDH and pyridoxal phosphate dependent enzymes) were observed at high levels in B. This indicates that degradation of amino acids and denitrification of nitrate may potentially occur in B. The high concentrations of the fatty acid degradation enzyme groups (enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase and beta-ketothiolase) were observed together with the denitrification genes, such as napA, narG and nosZ. Phospholipase/carboxylesterase, enoyl-CoA hydratase/isomerase, acyl-CoA dehydrogenase, phenylacetate degradation enzyme and 3-hydroxyacyl-CoA dehydrogenase 2 were also dominant in B. All these results clearly indicate that the denitrification pathways are potentially linked to the degradation pathways of amino acids and fatty acids whose degradation products go through the TCA cycle, generating the NADH that is used as electron donors for denitrification.
Delayed dynamic triggering of deep tremor along the Parkfield-Cholame section of the San Andreas Fault following the 2014 M6.0 South Napa earthquake
GEOPHYSICAL RESEARCH LETTERS
Authors: Peng, Zhigang; Shelly, David R.; Ellsworth, William L.
Abstract
Large, distant earthquakes are known to trigger deep tectonic tremor along the San Andreas Fault and in subduction zones. However, there are relatively few observations of triggering from regional distance earthquakes. Here we show that a small tremor episode about 12-18km NW of Parkfield was triggered during and immediately following the passage of surface waves from the 2014 M-w 6.0 South Napa main shock. More notably, a major tremor episode followed, beginning about 12h later, and centered SE of Parkfield near Cholame. This major episode is one of the largest seen over the past several years, containing intense activity for 3days and taking more than 3weeks to return to background levels. This episode showed systematic along-strike migration at 5km/d, suggesting that it was driven by a slow-slip event. Our results suggest that moderate-size earthquakes are capable of triggering major tremor and deep slow slip at regional distances.