Isolated cellulolytic extreme thermophilic bacterial cells belonging to the genus Caldicellulosiruptor, mutants thereof, isolated strains, microbial cultures and microbial compositions. The novel bacteria are in particular suitable for the production of fermentation products such as lactic acid from any carbon source, not limited to cellulosic material but especially useful for converting cellulosic biomass like ligniocellulosic biomass and/or starch containing biomass.

A method for producing hydrogen gas (H.sub.2) from sweet sorghum (Sorghum bicolor (L.) Moench) comprising: (i) preparing materials; (ii) creating a first temporary mixture; (iii) creating a second temporary mixture; (iv) creating a third temporary mixture; (v) creating a first base mixture; (vi) fermenting the first base mixture under dark conditions to produce a first hydrogen gas and a dark fermented base mixture; (vii) creating a second base mixture; (viii) fermenting the second base mixture under light conditions to produce a second hydrogen gas; and (ix) purifying the first hydrogen gas and the second hydrogen gas to obtain a hydrogen gas purity of over 99%.

Methods, tools and kits allowing genetic modification, involving in particular a nucleic acid sequence used to facilitate the transformation of bacteria of the phylum Firmicutes, the sequence comprising i) all or part of the sequence SEQ ID NO: 126 and ii) a sequence allowing the modification of the genetic material of a bacterium and/or expression, within a bacterium, of a DNA sequence partially or totally absent from the genetic material present within the wild-type version of the bacterium are provided. Also provided are genetically modified bacteria and uses thereof, in particular for producing a solvent, preferably on an industrial scale.

Species of human-derived bacteria belonging to the Clostridia class have been shown to induce accumulation of regulatory T cells (Treg cells) in the colon and suppress immune functions. Pharmaceutical compositions containing these bacteria can be used to prevent and treat immune-mediated diseases such as autoimmune diseases.

Microbial cell lines suitable for industrial-scale production of organic acids and methods of making and isolating such cell lines, and using the cell lines for production of organic acids.