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The Firmicutes Thermoanaerobacter sulfurigignens and Thermoanaerobacterium thermosulfurigenes convert thiosulfate, forming sulfur globules inside and outside cells. X-ray absorption near-edge structure analysis revealed that the sulfur consisted mainly of sulfur chains with organic end groups similar to sulfur formed in purple sulfur bacteria, suggesting the possibility that the process of sulfur globule formation by bacteria is an ancient feature.

The isoprenoid lipid crenarchaeol is widespread in hotsprings of California and Nevada and terrestrial and marine data together suggest a maximum relative abundance of crenarchaeol at -40 degrees Celsius. This warm temperature optimum may have facilitated colonization of the ocean by (hyper) thermophilic Archaea and the major marine radiation of Crenarchaeota.

Diverse microbial communities and numerous energy-yielding activities occur in deeply buried sediments of the eastern Pacific Ocean. Distributions of metabolic activities often deviate from the standard model. Rates of activities, cell concentrations, and populations of cultured bacteria vary consistently from one subseafloor environment to another. Net rates of major activities principally rely on electron acceptors and electron donors from the photosynthetic surface world. At open-ocean sites, nitrate and oxygen are supplied to the deepest sedimentary communities through the underlying basaltic aquifer. In turn, these sedimentary communities may supply dissolved electron donors and nutrients to the underlying crustal biosphere., Microbial life is widespread in the marine sediments that cover more than two-thirds of Earth's surface. Intact cells (1) and intact membrane lipids (2, 3) provide evidence of prokaryotic populations [...]

Advances in the genetic engineering of Thermoanaerobacterium spp. are discussed. This organism can survive at temperatures up to 80 deg. C. and can use xylan, which is a cheap substrate for industrial fermentation.

The biochemical pathway involved in the fermentation of inulin by Clostridium thermosuccinogenes is discussed. It involves nine enzymes and the ratio of oxidized products to reduced products increased as the temperature increased from 58 to 70 deg C.

A novel gene, called ohb1, which encodes the oxygen-sensitive and biotin-, ATP-, thiamin-, pyridoxal phosphate-, and metal-ion-independent, reversible 4-hydroxybenzoate decarboxylase (4-HOB-DC) from the obligate anaerobe Clostridium hydroxybenzoicum JW/Z-1T was sequenced and expressed. The 1,440-bp open reading frame encodes 480 amino acids. The main characteristics of the heterologous enzyme Ohb1 expressed in Escherichia coli DH5alpha were the same as those for the native 4-HOB-DC.

Para-hydroxylated polychlorinated biphenyls undergo rapid anaerobic dehalogenation by Desulfitobacterium dehalogenans. Desulfitobacterium dehalogenans totally dehalogenates all bordering chlorines from congeners such as 3,3', 5,5'-tetrachloro-4,4'-dihydroxybiphenyl. The bulky phenyl ring in the ortho position to the hydroxyl group hinders the correct interaction between the hydroxyl group and the enzyme, suggesting that no proper binding of these congeners to the dehalogenating enzyme of Desulfitobacterium takes place.

A research was conducted to examine reductive dechlorination of the Aroclor 1260 residue at the Woods Pond in Lenox, MA. The sediment slurries were incubated anaerobically with and without 2,3,4,6-tetrachloribiphenyl as a primer for dechlorination of the Aroclor 1260 residue. Polychlorinated biphenyls were extracted with anhydrous diethyl ether containing octachloronaphthalene. Results suggested that temperature effects on dechlorination will assist in predictions of environmental fate and in the development of bioremediation strategies.