Soil bacterial community diversity of different forest types in southern subtropical Guangxi and their correlation to soil chemical properties

【Objective】The objective of this study was to explore the diversity and composition of soil bacterial communities in different forest types, as well as the correlation between soil bacterial communities and soil factors, so as to provide reference for mastering the soil bacterial community structure in the forest ecosystem in southern China. 【Method】High-throughput sequencing technology combined with soil physicochemical properties experiment was used to classify and identify the soil bacterial community structure, and the soil physicochemical indexes such as pH, soil moisture content, organic matter(OM), available nitrogen(AN), available phosphorus(AP), available potassium(AK), calcium(Ca), magnesium(Mg), total phenols, complex phenols and water-soluble phenols were determined. The differences in soil bacterial community diversity in Eucalyptus spp. forest, Pinus massoniana Lamb. forest, P. massoniana and Lithocarpus glaber(Thunb.) Nakai mixed coniferous and broad-leaved mixed forest and Osmanthus sp. forest were analyzed. 【Result】A total of 731289 effective sequences of endophytic bacteria were obtained from soil samples of four forest types by sequencing, and 6320 operational taxonomic units(OTUs) were annotated, with a total of 57 species, 152 genera, 136families, 116 orders, 85 classes, 36 phyla in 2 kingdoms. Among them, the dominant bacterial phyla were Proteobacteria(33.16%), Actinobacteria(30.24%), Acidobacteria(16.83%) and Chloroflexi(6.71%), and the dominant bacterial genera were Rhodoplanes(7.72%), Mycobacterium(2.82%), Candidatus_Solibacter(1.57%), Bradyrhizobium(0.91%) and Burkholderia(0.67%). Among the different forest ecosystems, the richness and diversity of soil bacterial communities were the highest in Osmanthus sp. forest, followed by Eucalyptus spp. forest, P. massoniana forest, and the richness and diversity of coniferous and broad-leaved mixed forest were the lowest. The results of redundancy analysis showed that pH(r=0.943) and AK(r=0.861) had extremely significant effects on bacterial community structure(P<0.01), among which the degree of influence of bacteria at the phylum classification level was pH>AK>complex phenols>total phenols>Ca>Mg>AP>water-soluble phenols>OM>AN and pH>AK>Ca>Mg>AP>total phenols>complex phenols>AN>water-soluble phenols>OM at the genus taxonomic level. 【Conclusion】The diversity and abundance of soil bacterial communities in the four forest types are mostly affected by pH and AK in soil chemical properties, and some phylum-level bacteria are greatly affected by soil phenols.