Screening Of Mineral-weathering Bacillus From The Surface Of Potassic Trachyte And Their Mineral-weathering Ability

In this study,Bacillus species were isolated from the rocks at different sites and the soils located in Xiaolongshan in Nanjing(China)and characterized for their potash feldspar weathering and populations.Also,the abundance of 16S rRNA genes of Bacillus species in the rock and soil samples was characterized through qRT-PCR.The study will provide the experimental basis for the roles of Bacillus species in mineral weathering,soil formation and element cycling.Eight hundred Bacillus strains were isolated from the rock(rock 1,2,and 3)and soil samples using selected medium with the treatment of 80 ? for 10 min in November,2014 and May,2015,The ratios of the Bacillus species to the total bacteria were 6.7%?7.0%?8.6%and 11.4%,respectively,in November,2014,while the ratios of the Bacillus species to the total bacteria were 6.5%?7.0%?7.4%and 9.8%,respectively,in May,2015.Compared to the controls,the Al content in the solution was increased by 3-18-fold in the presence of the Bacillus species.16S rRNA gene sequence analysis showed that the Bacillus species belonged to Bacillus aryabhattai?Bacillus anthracis?Bacillus megaterium?Bacillus thuringiensis?Bacillus amyloliquefaciens?Bacillus subtilis?Bacillus aerophilus?Bacillus tequilensis.The soil sample collected in November,2014 had the most species,with Bacillus cereus and Bacillus aryabhattai being the specific species.The rock 1 sample collected in May,2015 had the most Bacillus species,with Bacillus amyloliquefaciens being the specific species.In addition,one Bacillus species was selected from each sample for their feldspar weathering potential and the mechanisms involved during 15 days of incubation.The results showed that the strains could increase Al and Fe in the solution by 10.3-18.8-fold and 2.3-15-fold respectively compared to the controls and the strains also increased the Ca and K release from feldspar.The strains could significantly reduce the pH of the culture medium and produce gluconic acid(1300-1800 mg L-1)at day 1 of incubation.In order to better understand the abundance of Bacillus species in the rock and soil samples,qRT-PCR was performed by universal primers of total bacteria and designed primers of Bacillus species.The result showed that the abundance of Bacillus species was 1.0%?1.1-1.4%?1.5-1.6%and 2.5-2.7%,respectively,in the soil,rock 1,rock 2,and rock 3 samples.The abundance of the Bacillus species was lowest in the soil samples and highest in the rock 3 samples.Similar abundance of the Bacillus species was observed in the respective samples collected at different time.