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Abstract

The cytoplasmic membrane of bacteria and archaea determine to a large extent the composition of the cytoplasm. Since the ion and in particular the proton and/or the sodium ion electrochemical gradients across the membranes are crucial for the bioenergetic conditions of these microorganisms, strategies are needed to restrict the permeation of these ions across their cytoplasmic membrane. The proton and sodium permeabilities of all biological membranes increase with the temperature. Psychrophilic and mesophilic bacteria, and mesophilic, (hyper)thermophilic and halophilic archaea are capable of adjusting the lipid composition of their membranes in such a way that the proton permeability at the respective growth temperature remains low and constant (homeo-proton permeability). Thermophilic bacteria, however, have more difficulties to restrict the proton permeation across their membrane at high temperatures and these organisms have to rely on the less permeable sodium ions for maintaining a high sodium-motive force for driving their energy requiring membrane-bound processes. Transport of solutes across the bacterial and archaeal membrane is mainly catalyzed by primary ATP driven transport systems or by proton or sodium motive force driven secondary transport systems. Unlike most bacteria, hyperthermophilic bacteria and archaea prefer primary ATP-driven uptake systems for their carbon and energy sources. Several high-affinity ABC transporters for sugars from hyperthermophiles have been identified and characterized. The activities of these ABC transporters allow these organisms to thrive in their nutrient-poor environments.

Correlating Microbial Diversity Patterns with Geochemistry in an Extreme and Heterogeneous Environment of Mine Tailings

“…Second, patterns of Ferroplasma and Leptospirillum abundance were apparently shaped by tailing pH. These acidophiles may use different types of pH homeostatic mechanisms to adapt to extremely acidic habitats, including a highly impermeable cell membrane to restrict proton influx into the cytoplasm (68,77) and a chemiosmotic gradient generated by a Donnan potential to inhibit proton influx into the cell and pump excess protons out of the cell (68). Copper cations may represent an important environmental stress at the SMC site.…”

Fossil Lipids for Life-Detection: A Case Study from the Early Earth Record

“…In addition to providing a barrier and structural integrity, lipid membranes host proteins and act as a dynamic medium that directly affects cellular processes, such as the regulation of metabolites across membranes and other protein-lipid interactions (Dowham and Bogdanov 2002;Konings et al 2002;Vorob'eva 2004). Consequently, organisms produce assorted lipid molecules and membrane structures to fulfill their functional roles, particularly at the environment-cell interface.…”

Adaptations of archaeal and bacterial membranes to variations in temperature, pH and pressure

“…Above T m , the phospholipid hydrocarbon chains are motile with a gradual increase of motility towards the core of the bilayer. The preferred liquid crystalline phase, therefore, provides a functional matrix for the many biochemical processes while being permeable to neutral molecules like H 2 O, CO 2 and O 2 , but impermeable to ions and solutes (Konings et al 2002; Mykytczuk et al 2007). To maintain sufficient membrane fluidity below their optimal growth temperatures, bacteria adopt a large variety of modifications to lower the T m (reviewed in (Chattopadhyay 2006; Chintalapati et al 2004; Russell 1997; Shivaji and Prakash 2010)).…”