Microbial intact polar and core lipids in hydrothermal chimneys of the Iheya North Hydrothermal Field in the Mid-Okinawa Trough
Archaeal CLs and IPLs were detected in all samples. The archaeal IPLs consist almost glycolipid, which is consistent with the higher glycolipid proportion with increasing growth temperature in cultured thermophilic archaea . Bacterial IPLs were also found except the NBC. The absence of bacterial IPLs in NBC was not consistent with the predominance of Epsilonproteobacteria reported by the previous gene-based survey before the drilling . Also, the lipid content of the NBC was significantly less than that of other chimneys. Those results clearly reflect the impact of drilling on the fluid chemistry and bacterial biomass. Interestingly, diacylglycerol homoserine (DGTS) was relatively abundant in C0016B. Though DGTS is widely distributed in lower plants and green algae, it is also present in anaerobic bacteria where phosphorus is limited . The distribution suggests that distinctive anaerobic bacteria thrive in the present artificial chimney, even though the detectable microbial communities were not developed in 11 months after the drilling .
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