Main controls on phoD-harboring bacterial community abundance, composition and activity from oil-contaminated soils at the Changqing Oilfield, Northwest China

Dandan Li¹Xianyuan Du²Xingchun Li^2*Xinyu Zhang³Jin Zheng²Qin Chu⁴Weiwen Qiu⁵Hanyu Zhang²Qingwei Wang²

• ¹Institute of Carbon Neutrality, Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Ecology, Northeast Forestry University, Harbin, China
• ²CNPC Research Institute of Safety and Environmental Technology, Beijing, China
• ³Chinese Academy of Sciences Institute of Geographic Sciences and Natural Resources Research, Beijing, China
• ⁴College of Life Science, Northeast Forestry University, Harbin, China
• ⁵The New Zealand Institute for Plant and Food Research Limited, Christchurch, New Zealand

Soil phosphorusavailability limits the native microbial activity, which then inhibits the petroleum hydrocarbon biodegradation. phoD-harboring bacteria that encode alkaline phosphatase (ALP) acts as a key player in the regulation of P availability in soils. Nevertheless, the consequences of oil contamination on ALP activity and phoD-harboring bacterial community dynamics are poorly understood. Here, contaminated and uncontaminated soils were collected in  the area surrounding crude oil pumping wells in the Changqing Oilfield to assess phoD -harboring bacterial abundance, community diversity, and ALP activity in response to oil contamination. It was shown that petroleum contamination markedly decreased the abundance, richness and diversities of phoD-harboring bacterial community, but greatly enhanced the relative abundance of phoD-harbouring Actinomycetia, Thermoleophilia, Rubrobacteria (P < 0.05). The relative abundances of phoD-harbouring Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria showed an increasing tendency and then decreased as the oil contamination concentration increasing (P < 0.05). The soil water, nutrient content (carbon, nitrogen, phosphorus) and the nutrient ratio were the crucial parameters influencing phoD-harbouring bacterial community responding to oil contamination. Activity of ALP was associated positively and negatively with the relative abundance of Betaproteobacteria and Rubrobacteria, respectively. The significant decline of ALP activity in the oil-contaminated soils was likely caused by reduced abundance and changes in composition of phoD-harbouring bacterial community, which were strongly dependent on the available N and P contents. These findings offer novel insights into how structure and functions of phoD-harbouring bacterial community were altered under oil pollution stress, and that this information would be useful for formulating plans of future bioremediation processes.