Genome analysis and reconstruction of metabolic pathways of amino acids and betaine degradation in the haloalkaliphilic bacteria <I>Anoxynatronum sibiricum</I>

The genome of the haloalkaliphilic anaerobic microorganism Anoxynatronum sibiricum Z-7981T isolated earlier from the Nizhneye Beloye soda lake (Republic of Buryatia, Russia) was analyzed. The ability of the organism to use betaine as an electron acceptor in the Stickland reaction was revealed. The introduction of betaine into the medium not only stimulated growth on amino acids used by A. sibiricum individually, but also allowed identifying additional amino acids, growth on which was not possible without the acceptor. Based on the genomic characteristics and experimental growth data, metabolic schemes of amino acid degradation in the presence and absence of betaine were proposed. Schemes for threonine, glutamate and lysine when used together with betaine were compiled for the first time. For all amino acids used, the qualitative and quantitative composition of the metabolic products was determined and the stoichiometric substrate/product ratios were obtained. Balance equations for the identified variants of the Stickland reaction, including those previously not described in the literature, have been compiled.