Brazilian Journal of Microbiology Brazilian Journal of Microbiology
Braz J Microbiol 2018;49:723-30 - Vol. 49 Num.4 DOI: 10.1016/j.bjm.2018.03.001
Environmental Microbiology
Outstanding impact of soil tillage on the abundance of soil hydrolases revealed by a metagenomic approach
Renata Carolini Souzaa,b, Maurício Egídio Cantãoc, Marco Antonio Nogueiraa,b, Ana Tereza Ribeiro Vasconcelosb,d, Mariangela Hungriaa,b,, , ,
a Embrapa Soja, C.P. 231, 86001-970 Londrina, PN, Brazil
b CNPq – Conselho Nacional de Desenvolvimento Científico e Tecnológico, SHIS QI 1 Conjunto B, Blocos A, B, C e D, Lago Sul, 71605-001 Brasília, DF, Brazil
c Embrapa Suínos e Aves, C.P. 21, 89700-000 Concórdia, SC, Brazil
d Laboratório Nacional de Computação Científica, Labinfo, Av. Getúlio Vargas 333, 25651-071 Petrópolis, RJ, Brazil
Received 01 January 2018, Accepted 02 March 2018
Abstract

The soil represents the main source of novel biocatalysts and biomolecules of industrial relevance. We searched for hydrolases in silico in four shotgun metagenomes (4,079,223 sequences) obtained in a 13-year field trial carried out in southern Brazil, under the no-tillage (NT), or conventional tillage (CT) managements, with crop succession (CS, soybean/wheat), or crop rotation (CR, soybean/maize/wheat/lupine/oat). We identified 42,631 hydrolases belonging to five classes by comparing with the KEGG database, and 44,928 sequences by comparing with the NCBI-NR database. The abundance followed the order: lipases>laccases>cellulases>proteases>amylases>pectinases. Statistically significant differences were attributed to the tillage system, with the NT showing about five times more hydrolases than the CT system. The outstanding differences can be attributed to the management of crop residues, left on the soil surface in the NT, and mechanically broken and incorporated into the soil in the CT. Differences between the CS and the CR were slighter, 10% higher for the CS, but not statistically different. Most of the sequences belonged to fungi (Verticillium, and Colletotrichum for lipases and laccases, and Aspergillus for proteases), and to the archaea Sulfolobus acidocaldarius for amylases. Our results indicate that agricultural soils under conservative managements may represent a hotspot for bioprospection of hydrolases.

Keywords
Metagenome, Microbiome, Soil enzymes, Soil management, No-tillage
Braz J Microbiol 2018;49:723-30 - Vol. 49 Num.4 DOI: 10.1016/j.bjm.2018.03.001