Abstract: Objective To explore the significance of evaluating first-stage lung lavage fluid based on high-throughput sequencing in the study of pulmonary bacterial diversity in pneumoconiosis patients. Methods A total of 34 lung lavage fluid samples were collected in different pneumoconiosis patients or different disease scenarios at different time periods. Genomic DNA was extracted from each sample according to the sixteen alkyl three methyl bromide（CTAB） instructions. The V4 primers of 16S rRNA gene was amplified.The sample sequences obtained by Illumina NovaSeq sequencing were spliced,standardized quality control,and bioinformatics analysis was performed. Results Effective tags of samples was 77.13%.Compared with the middle and posterior lung lavage fluid,the horizontal species of the first lung lavage fluid group were dominated by Firmicutes,Proteobacteria,Bacteroidota and Actinobacteria,and the Bacteroidete was not underestimated,nor before and after antibiotic treatment.There were no difference in the richness and Shannon index of lung lavage fluid collected in the first segment and other time period（both P>0.05）.Flora richnessand evenness in all segments of lung lavage fluid were similar.There were significant differences of the richness and Shannon index of lung lavage fluid in the first segment of lung lavage fluid in different individuals（both P<0.05）.The first segment lung lavage fluid can distinguish the characteristics of lung flora in different individuals. There was significant difference in the richness of first segment lung lavage fluid before and after antibacterial treatment（P<0.05）,but no difference in Shannon index（P>0.05）.The first segment lung lavage fluid can distinguish the changes of pulmonary flora characteristics in the anti-inflammatory scenario.The Beta diversity was no difference in between the first and other segment lung lavag（P>0.05）,but significant differences were found between individuals and before and after anti-inflammatory treatment（both P<0.05）.The first segment lung lavage fluid can distinguish the changes of lung flora composition in different intervention scenarios,and reflect the individual differences of lung flora composition. Conclusions The first-stage lung lavage solution can more sensitively reflect the structural information of pulmonary microbiota in pneumoconiosis patients,which may be an excellent choice to analyze the information of occupational pulmonary bacterial community with high-throughput 16S rRNA label sequencing.

Key words: Pneumoconiosis, Microbiome, 16S rRNA, Lavage fluid