Souza Renata Carolini, Cantão Maurício Egídio, Nogueira Marco Antonio, Vasconcelos Ana Tereza Ribeiro, Hungria Mariangela
Embrapa Soja, C.P. 231, 86001-970 Londrina, PN, Brazil; 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.
Embrapa Suínos e Aves, C.P. 21, 89700-000 Concórdia, SC, Brazil.
Braz J Microbiol. 2018 Oct-Dec;49(4):723-730. doi: 10.1016/j.bjm.2018.03.001. Epub 2018 Mar 31.
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.
土壤是具有工业相关性的新型生物催化剂和生物分子的主要来源。我们在巴西南部进行的一项为期13年的田间试验中，通过免耕（NT）或传统耕作（CT）管理，作物连作（CS，大豆/小麦）或作物轮作（CR，大豆/玉米/小麦/羽扇豆/燕麦）获得的四个鸟枪法宏基因组（4,079,223个序列）中，通过计算机搜索水解酶。通过与KEGG数据库比较，我们鉴定出42,631种属于五类的水解酶，通过与NCBI-NR数据库比较，鉴定出44,928个序列。丰度顺序为：脂肪酶>漆酶>纤维素酶>蛋白酶>淀粉酶>果胶酶。统计上的显著差异归因于耕作系统，免耕系统中的水解酶比传统耕作系统多约五倍。显著差异可归因于作物残茬的管理，免耕时残茬留在土壤表面，而传统耕作时残茬被机械破碎并混入土壤中。作物连作和作物轮作之间的差异较小，作物连作的差异高10%，但无统计学差异。大多数序列属于真菌（脂肪酶和漆酶的轮枝菌和炭疽菌，蛋白酶的曲霉），以及淀粉酶的嗜热栖热放线菌。我们的结果表明，保守管理下的农业土壤可能是水解酶生物勘探的热点。
