Quinone profiling of bacterial populations developed in the surface layer of volcanic mudflow deposits from Mt. Pinatubo (the Philippines)

The diversity of bacterial populations developed in the surface layer (0–0.25 m depth) of volcanic mudflow deposits from the Mt. Pinatubo volcano (the Philippines) was investigated using quinone profiling. Samples were collected from sites (named N and S1) that had been hit repeatedly by mudflows during successive rainy seasons after the violent eruption of 1991 and also from sites (F1 and F3) covered by mudflow in 1991 but with no deposition in following years. The total microscopic count ranged from 108 g−1 (N and S1 sites) to 3.9×109 g−1(site F3). In the N sample only three quinone species were detected, while the quinone profiles of samples from sites S3 and F3 showed higher diversity. Tetrahydrogenated menaquinone with eight isoprenoid units [MK-8 (H4)] was the predominant quinone species in the sample from site N, while MK-8, MK-8 (H2), MK-8 (H4), MK-9 (H4) and MK-9 (H8) were found as major quinones in the sample from site F3. Because these MK species are known to be the major respiratory quinones of the Actinobacteria, this bacterial group is expected to predominate in the land with primary vegetation recovery following the impact of the volcanic mudflow.