Rui Zhipeng, Lu Xinda, Li Zichuan, Lin Zhi, Lu Haifei, Zhang Dengxiao, Shen Shengyuan, Liu Xiaoyu, Zheng Jufeng, Drosos Marios, Cheng Kun, Bian Rongjun, Zhang Xuhui, Li Lianqing, Pan Genxing
Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing, China.
Department of Soil Science, Nanjing Agricultural University, Nanjing, China.
Front Microbiol. 2022 Apr 11;13:831746. doi: 10.3389/fmicb.2022.831746. eCollection 2022.
Microbial communities of soil aggregate-size fractions were explored with molecular and networking assays for topsoil samples from a clayey rice paddy under long-term fertilization treatments. The treatments included no fertilizer (NF) as control, chemical fertilizer only (CF), chemical fertilizer with swine manure (CFM), and chemical fertilizer with rice straw return (CFS). Following a wet-sieving protocol, water-stable aggregates were separated into size fractions of large macroaggregates (L-MacA, >2,000 μm), macroaggregates (MacA, 2,000-250 μm), microaggregates (MicA, 250-53 μm), fine microaggregates (F-MicA, 53-2 μm), and fine clay (F-Clay, <2 μm). Mass proportion was 32.3-38.2% for F-MicA, 23.0-31.5% for MacA, 19.0-23.1% for MicA, 9.1-12.0% for L-MacA, and 4.9-7.5% for F-Clay, respectively. The proportion of MacA was increased, but F-Clay was reduced by fertilization, whereas the mean weight diameter was increased by 8.0-16.2% from 534.8 μm under NF to 621.5 μm under CFM. Fertilization affected bacterial 16S rRNA and fungal 18S rRNA gene abundance in F-MicA and F-Clay but not in aggregates in size larger than 53 μm. However, bacterial and fungal community α-diversities and community structures were quite more divergent among the fertilization treatments in all size fractions. Organic carbon and gene abundance of bacteria and fungi were enriched in both L-MacA and MacA but depleted in F-Clay, whereas microbial Shannon diversity was rarely changed by fraction size under the four treatments. L-MacA and MacA contained more bacteria of r-strategists and copiotrophs, whereas F-MicA and F-Clay were demonstrated with a higher abundance of K-strategists and oligotrophs. Guilds of parasitic and litter saprotrophic fungi were enriched in F-MicA but depleted in L-MacA. Furthermore, most of bacterial and fungal operational taxonomic units were strongly interacted in L-MacA and MacA rather than in MicA and F-Clay. Thus, MacA acted as micro-hotspots enriched with functional and networked microbial communities, which were enhanced with organic/inorganic fertilization in the rice paddy.
采用分子和网络分析方法，对长期施肥处理下的黏性水稻土表土样本中土壤团聚体大小分级的微生物群落进行了探究。处理包括不施肥（NF）作为对照、仅施化肥（CF）、化肥与猪粪混合（CFM）以及化肥与稻草还田（CFS）。按照湿筛法，将水稳性团聚体分离为大团聚体（L-MacA，>2000μm）、团聚体（MacA，2000 - 250μm）、微团聚体（MicA，250 - 53μm）、细微团聚体（F-MicA，53 - 2μm）和细黏土（F-Clay，<2μm）等大小分级。质量比例分别为：F-MicA为32.3 - 38.2%，MacA为23.0 - 31.5%，MicA为19.0 - 23.1%，L-MacA为9.1 - 12.0%，F-Clay为4.9 - 7.5%。施肥使MacA的比例增加，但F-Clay的比例降低，而平均重量直径从NF处理下的534.8μm增加到CFM处理下的621.5μm，增幅为8.0 - 16.2%。施肥影响了F-MicA和F-Clay中细菌16S rRNA和真菌18S rRNA基因丰度，但对大于53μm的团聚体没有影响。然而，在所有大小分级中，不同施肥处理间细菌和真菌群落的α多样性及群落结构差异更大。有机碳以及细菌和真菌的基因丰度在L-MacA和MacA中富集，但在F-Clay中减少，而在四种处理下，微生物香农多样性很少因分级大小而改变。L-MacA和MacA含有更多的r策略者和富营养型细菌，而F-MicA和F-Clay中K策略者和贫营养型细菌的丰度更高。寄生和凋落物腐生真菌类群在F-MicA中富集，但在L-MacA中减少。此外，大多数细菌和真菌的操作分类单元在L-MacA和MacA中相互作用强烈，而在MicA和F-Clay中则不然。因此，MacA作为富含功能和网络化微生物群落的微热点，在稻田中通过有机/无机施肥得到增强。
