Characteristics of carbon fixing bacteria community in tropical farmland soils with different abandoned years in Hainan Island
[Objective]The paper aimed to explore the impact of different years of abandonment in tropical regions on soil carbon fixing bacte-rial communities in farmland,and provide theoretical basis and data support for sustainable agricultural management.[Method]Real time quantitative PCR and high-throughput sequencing technology were used to analyze the gene abundance,community diversity,and differences of soil carbon fixing bacteria in farmland,short-term abandoned land(2＜abandoned years＜5),and long-term abandoned land(abandoned years＞5)in the central region of Hainan Island.[Result]The abundance of cbbL gene in the soil within the region ranged from 3.11 × 107-2.84 × 108 copies/g of dry soil,showing a trend of farmland＞short-term abandoned land＞long-term abandoned land.Compared with the control farmland,long-term abandoned land reduced the Chao1 index,Observed Specifications index and Shannon index of soil carbon fixing bacteria.The dominant phyla of carbon fixing bacteria in tropical farmland soils with different abandonment years were Pseudomonadota and Actinomycetota,and the dominant genera were Bradyrhizobium,Mycobacterium,Rhodopseudomonas,Rubrivivax,Blastochlolis,Nocardia,Meso-rhizobium,Dokdonella and Azospirillum,and most of them were facultative autotrophic bacteria.The overall changes in the community struc-ture of soil carbon fixing bacteria with different abandonment years showed clustering according to each abandonment year.A total of 33 dif-ferential markers were analyzed for three different abandonment years of soil,including 17 in farmland,5 in short-term abandonment land,and 11 in long-term abandonment land.The RD A results showed that the community structure of soil carbon fixing bacteria was significantly influ-enced by SOC,SWC,ROC,TP,TN,Coarse sand,pH and Fine sand.[Conclusion]The increase in abandoned years has reduced the gene a-bundance of soil carbon fixing bacteria,and the community structure has also changed.Environmental factors such as SOC,SWC,ROC,TP and TN have a significant impact on the community structure of soil carbon fixing bacteria.
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