Microbial dormancy in the marine subsurface: Global endospore abundance and response to burial

Abstract

Bacterial endospores are dominant members of the marine deep biosphere.

Dormancy dampens the microbial distance-decay relationship

“…Large portions of microbial abundance and diversity can be found within dormant seed banks[1, 15]. The direct observation of seed banks is a significant challenge for microbial ecology and for the greater understanding of microbial diversity and biogeography.…”

“…Microorganisms are well known to accumulate in seed banks by forming cysts, spores, and other morphological resting stages that are highly resilient to fluctuations in a wide range of environmental conditions. For example, recent estimates suggest there are more than 10 29 endospores in the marine subsurface alone [15]. In addition, microorganisms can engage in less conspicuous forms of dormancy that involve the downregulation of metabolic activities, which allows individuals to extend their lifespan for prolonged periods of time [16].…”

“…In addition, microorganisms can engage in less conspicuous forms of dormancy that involve the downregulation of metabolic activities, which allows individuals to extend their lifespan for prolonged periods of time [16]. As a result, microbial seed banks can account for the vast majority of individuals and biomass in some ecosystems [1, 15, 17, 18]. Historically, microorganisms have also been thought to have relatively unhindered capacities for dispersal, in part, through the influence that dormancy has on improving the odds of successful dispersal and colonization [9].…”

Sub‐seafloor biogeochemical processes and microbial life in the Baltic Sea

“…This trend is similar to the global marine database on endospores and cell numbers compiled by Wörmer et al . (). They also found an endospore: cell ratio of about 1:100 near the sediment surface increasing to about 100:1 below 100 mbsf.…”

“…The latter is much higher than in the Baltic Sea, possibly due to the young sediments and high organic matter turnover in the Baltic compared to open ocean sites at the same sediment depth. It remains unknown what controls the endospore numbers in the oceanic seabed where their abundance remains surprisingly constant at approximately 10 5 –10 6 endospores cm −3 between <1 and 500 m depth (Wörmer et al ., ). The lack of a systematic depth trend may indicate that endospores from the near‐surface sediment simply survive for millions of years during burial into the seabed.…”