Environmental Engineering Reference
In-Depth Information
Figure 3.
Depth profiles of biomarkers (carotenoids and 16S rDNA) of anoxygenic pho-
tolithotrophic green sulfur bacteria recovered from filtered particulate organic matter from the
water column of Ace Lake. A dense population of green sulfur bacteria comprised of a species
with 99.7% sequence similarity to
Chlorobium phaeovibrioides
(phylotype AL-GSB 1) is located
just below the anoxic-oxic interface (OAI) where light and sulfide are available for anoxygenic
photosynthesis. Below the bacterial plate, light for photosynthesis is absent [6].
(a) Concentration of chlorobactene and isorenieratene (mg.L
−
1
), (b) 16S rDNA of the predom-
inant GSB [AL-GSB 1, (ng.L
−
1
)]. This was the only GSB phylotype detected from the water
column and the most likely source of the predominant carotenoid chlorobactene. (c) Ratio
(Log
10
) between phylotype AL-GSB 1 (ng.L
−
1
) to chlorobactene (mg.L
−
1
). (d) abundance of
phylotype Al-GSB 1 as % of total DNA.
Diagenetic products of chlorobactene such as its hydrogenated form, chloro-
bactane, would be missed by UV detection during HPLC analysis. To allow the
identification of chlorobactane, apolar fractions of total lipids were extracted
from sediment layer 37
87 cm, hydrogenated, and analyzed
by GC-MS. The amount of chlorobactene and chlorobactane in both sediment
−
39 cm and 85
−
