Bacterial community structure and putative nitrogen-cycling functional traits along a charosphere gradient under waterlogged conditions

Abstract

Unique spatial niches created by biochar form a dynamic biogeochemical soil zone, termed the "charosphere". Charosphere soil has different properties from either soil or biochar, often acting as a hotspot for microbial activity. However, the direction and magnitude of charosphere effects on soil processes and microbial communities remain inconclusive. Herein, we designed a multi-sectional box to separate charosphere soils from biochar under waterlogged conditions, investigating millimeter-scale changes in bacterial communities and distributions of specific genera across the charosphere created by pristine biochar (produced from corn stover at 300 • C), acid-modified biochar and washed biochar. The pristine biochar did not increase bacterial α-diversity but altered bacterial composition by promoting the growth of specific bacterial taxa and suppressing other species. In comparison, washed and acid-modified biochar increased the bacterial α-diversity. The pristine biochar significantly decreased N 2 O emission and NO 3 − concentration owing to a lower soil nitrification potential. Abundances of N-cycling functional taxa were higher in the near-charosphere than outer-charosphere zone, especially for Bacillus (N 2 -fixation), MND1 (ammonia oxidation) and Rhodopseudomonas (denitrification). The spatial distribution of functional genes and genera documents the importance of heterogeneity within the charosphere gradient, providing a novel perspective into functional geometry to understand how biochar reduces N losses from agroecosystems.

pH-Related Changes in Soil Bacterial Communities in the Sanjiang Plain, Northeast China

“…Previous studies reported that MND1 played a pivotal role in soil nitrogen cycling [86]. RB41 exhibited the remarkable ability to selectively regulate the decomposition of soil organic matter and the carbon cycling process in agricultural soils and positively correlated with soil pH [87][88][89]. We believe that this is the reason that certain bacteria have evolved effective strategies to thrive in extreme environments.…”

Lab‐scale data and microbial community structure suggest shortcut nitrogen removal as the predominant nitrogen removal mechanism in post‐aerobic digestion (PAD)

“…The composition of AOB is quite similar with Nitrosomonas being the key genera in both samples (Figure 5c,d). Other shared bacteria include the uncultured genus Ellin6067 and MND1, belonging to the family Nitrosomonadaceae are also of note and are both involved in NH 4 + oxidation processes (Wang et al, 2021; Yu et al, 2021). Chloroflexi here identified at the phylum level was only found in the PAD's test B biomass sample (Figure 5c); this phylum has been often found associated with thermophilic environment and with NH 4 + oxidation (Herber et al, 2020).…”

Interspecific plant interaction structures the microbiomes of poplar-soil interface to alter nutrient cycling and utilization

“…Bradyrhizobium has a symbiotic relationship with leguminous plants and participates in nitrogen fixation ( 56 ). Gemmatimonadaceae and Sphingomonas are known plant-promoting microorganisms, which can dissolve phosphorus, sulfur, and calcium and produce a variety of plant hormones and iron carriers ( 57 , 58 ). Changes in Sphingomonas , a rhizosphere biomarker, could prove that the poplar rhizosphere provides sufficient air and organic nutrient conditions for these microorganisms ( 57 ).…”

“…Gemmatimonadaceae and Sphingomonas are known plant-promoting microorganisms, which can dissolve phosphorus, sulfur, and calcium and produce a variety of plant hormones and iron carriers ( 57 , 58 ). Changes in Sphingomonas , a rhizosphere biomarker, could prove that the poplar rhizosphere provides sufficient air and organic nutrient conditions for these microorganisms ( 57 ). It has been demonstrated that microbial communities isolated from Populus can enhance the health, growth, and development of plant hosts ( 43 , 46 ).…”