TY - JOUR

T1 - Earthworm gut

T2 - An overlooked niche for anaerobic ammonium oxidation in agricultural soil

AU - Li, Hu

AU - Yang, Xiao-Ru

AU - Wang, Juan

AU - Zhou, Guo-Wei

AU - Zhang, Yu-Sen

AU - Lassen, Simon Bo

AU - Zhu, Yong-Guan

AU - Su, Jian-Qiang

PY - 2021

Y1 - 2021

N2 - Soil fauna takes an active part in accelerating turnover of nutrients in terrestrial ecosystems. Anaerobic ammonium oxidation (anammox) has been widely characterized, however, whether anammox is active in earthworm gut and the effect of earthworm on anammox in soil remain unknown. In this study, the activity, abundance and community of anammox bacteria in earthworm guts and soils from microcosms were determined using a N-15-tracing technique, quantitative PCR, and anammox bacterial 16S rRNA gene amplicon sequencing. Results showed that anammox rates in guts ranged between 5.81 and 14.19 nmol N g(-1) dw gut content h(-1), which were significantly (P <0.01) higher than that in their surrounding soils during 30 day incubation. On the contrary, abundances of hzsB genes encoding subunit B hydrazine synthase in guts were significantly (P <0.05) lower than those in their surrounding soils. Anammox rates, denitrification N-2 production rates and hzsB genes in soils with earthworms were significantly (P <0.05) lower than those in control soils. Anammox bacterial compositions differed significantly (P <0.05) between gut and soil, and earthworm altered anammox bacterial communities in soils. Brocadia, Kuenenia and abundant unclassified anammox bacteria were detected in collected soils and gut contents, in which Brocadia was only detected in guts. These results suggested that microbes in earthworm gut increase, but present of earthworm reduces anammox and denitrification associated N loss by altering the anammox bacterial community compositions in soils. (C) 2020 Elsevier B.V. All rights reserved.

AB - Soil fauna takes an active part in accelerating turnover of nutrients in terrestrial ecosystems. Anaerobic ammonium oxidation (anammox) has been widely characterized, however, whether anammox is active in earthworm gut and the effect of earthworm on anammox in soil remain unknown. In this study, the activity, abundance and community of anammox bacteria in earthworm guts and soils from microcosms were determined using a N-15-tracing technique, quantitative PCR, and anammox bacterial 16S rRNA gene amplicon sequencing. Results showed that anammox rates in guts ranged between 5.81 and 14.19 nmol N g(-1) dw gut content h(-1), which were significantly (P <0.01) higher than that in their surrounding soils during 30 day incubation. On the contrary, abundances of hzsB genes encoding subunit B hydrazine synthase in guts were significantly (P <0.05) lower than those in their surrounding soils. Anammox rates, denitrification N-2 production rates and hzsB genes in soils with earthworms were significantly (P <0.05) lower than those in control soils. Anammox bacterial compositions differed significantly (P <0.05) between gut and soil, and earthworm altered anammox bacterial communities in soils. Brocadia, Kuenenia and abundant unclassified anammox bacteria were detected in collected soils and gut contents, in which Brocadia was only detected in guts. These results suggested that microbes in earthworm gut increase, but present of earthworm reduces anammox and denitrification associated N loss by altering the anammox bacterial community compositions in soils. (C) 2020 Elsevier B.V. All rights reserved.

KW - Anammox

KW - Soil fauna

KW - Gut microbiota

KW - Agricultural soil

KW - Nitrogen cycle

KW - IN-SITU DETECTION

KW - OXIDIZING BACTERIA

KW - NITROGEN LOSS

KW - DENITRIFYING BACTERIA

KW - MICROBIAL BIOMASS

KW - ORGANIC-MATTER

KW - ANAMMOX

KW - DENITRIFICATION

KW - NITRIFICATION

KW - TEMPERATURE

U2 - 10.1016/j.scitotenv.2020.141874

DO - 10.1016/j.scitotenv.2020.141874

M3 - Journal article

C2 - 32889284

VL - 752

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

M1 - 141874

ER -