Production of amino acids by free-living heterotrophic nitrogen-fixing bacteria (original) (raw)
Related papers
Liberation of amino acids by heterotrophic nitrogen fixing bacteria
Amino Acids, 2005
Large amounts of amino acids are produced by nitrogen-fixing bacteria such as Azotobacter, Azospirillum, Rhizobium, Mesorhizobium and Sinorhizobium when growing in culture media amended with different carbon and nitrogen sources. This kind of bacteria live in close association with plant roots enhanced plant growth mainly as a result of their ability to fix nitrogen, improving shoot and root development suppression of pathogenic bacteria and fungi, and increase of available P concentration. Also, it has been strongly evidenced that production of biologically substances such as amino acids by these rhizobacteria are involved in many of the processes that explain plant-grown promotion. This paper reviews literature concerning amino acids production by nitrogen-fixing bacteria. The role of amino acids in microbial interactions in the rhizosphere and establishment of plant bacterial association is also discussed.
Amino Acids, 2005
Azotobacter vinelandii strain ATCC 12837 and Azotobacter chroococcum strain H23 (CECT4435) were tested to grow in N-free or NH 4 Cl amended chemically defined media, with protocatechuic acid or sodium p-hydroxybenzoate as sole carbon (C) sources at a concentration of 2 mmol=L. Both substrates supported grow at similar rates than bacteria grown in control media amended with 2 mmol=L sodium succinate as C source. The two strains produced aspartic acid, serine, glutamic acid, glycine, hystidine, threonine, arginine, alanine, proline, cysteine, tyrosine, valine, methionine, lysine, isoleucine, leucine and phenylalanine after 72 h of growth in chemically defined media with 2 mmol=L of phenolic compounds or sodium succinate as sole C source amended or unamended with 0.1% (w=v) NH 4 Cl. Qualitative and quantitative production of all amino acids was not affected by the use of different C and N substrates.
Pakistan journal of zoology
The present study is designed to investigate the enhanced production of amino acids by bacterial strains isolated from different natural sources including sewage water, fresh milk, honey, yoghurt and soil. Sixty five bacterial isolates from these natural sources were isolated and nineteen isolates were found to be producers of amino acids. These isolates were grown in different fermentation media to enhance amino acid production. Out of nineteen, five bacterial isolates were good producers of methionine, cysteine, glutamic acid and valine. On the basis of 16SrRNA nucleotide sequences these organisms were identified as Bacillus anthracis, Bacillus cereus, Escherichia coli H, Escherichia coli M2 and Bacillus sp. The optimum temperature for the growth of B. anthracis and E. coli was found to be 37°C, while B. cereus and E. coli showed optimum growth at 30°C. Bacillus sp. showed its optimum growth at 39°C. B. anthracis, E. coli H and Bacillus sp. showed optimum growth at pH 7, while opt...
FEMS Microbiology Letters, 2004
In this work, we report the detection of aromatic amino acid aminotransferase (AAT) activity from cell-free crude extracts of nine strains of N 2-fixing bacteria from three genera. Using tyrosine as substrate, AAT activity ranged in specific activity from 0.084 to 0.404 lmol min À1 mg À1. When analyzed under non-denaturating PAGE conditions; and using tryptophan, phenylalanine, tyrosine, and histidine as substrates Pseudomonas stutzeri A15 showed three isoforms with molecular mass of 46, 68 and 86 kDa, respectively; Azospirillum strains displayed two isoforms which molecular mass ranged from 44 to 66 kDa and Gluconacetobacter strains revealed one enzyme, which molecular mass was estimated to be much more higher than those of Azospirillum and P. stutzeri strains. After SDS-PAGE, some AAT activity was lost, indicating a differential stability of proteins. All the strains tested produced IAA, especially with tryptophan as precursor. Azospirillum strains produced the highest concentrations of IAA (16.5-38 lg IAA/mg protein), whereas Gluconacetobacter and P. stutzeri strains produced lower concentrations of IAA ranging from 1 to 2.9 lg/mg protein in culture medium supplemented with tryptophan. The IAA production may enable bacteria promote a growth-promoting effect in plants, in addition to their nitrogen fixing ability.
Production of Free Amino Acid by Three Anoxygenic Phototrophic Purple Bacteria
2015
Production of Free Amino Acids (FAA) by three anoxygenic phototrophic purple bacteria Allochromatium sp. GSKRLMBKU-01, Rhodobacter sp. GSKRLMBKU-02 and Rhodobacter sp. GSKRLMBKU-03 isolated from different ecological niches was investigated. These three bacteria differed significantly in the amount of FAA produced. The maximum FAA production by Allochromatium sp. GSKRLMBKU-01 (642 μg/ml), Rhodobacter sp. GSKRLMBKU-02 (548 μg/ml) and Rhodobacter sp. GSKRLMBKU-03 (510 μg/ml) was recorded. The biomass and FAA production was maximum on 8 day of incubation by Allochromatium sp. GSKRLMBKU-01 and Rhodobacter sp. GSKRLMBKU-03 and decreased further progress of incubation period, while it was 10 day for Rhodobacter sp. GSKRLMBKU-02. Final pH of the medium was shifted towards alkaline side by all the three phototrophic bacteria.
Microbial Biotechnology
SummaryThe growing world needs commodity amino acids such as L‐glutamate and L‐lysine for use as food and feed, and specialty amino acids for dedicated applications. To meet the supply a paradigm shift regarding their production is required. On the one hand, the use of sustainable and cheap raw materials is necessary to sustain low production cost and decrease detrimental effects of sugar‐based feedstock on soil health and food security caused by competing uses of crops in the feed and food industries. On the other hand, the biotechnological methods to produce functionalized amino acids need to be developed further, and titres enhanced to become competitive with chemical synthesis methods. In the current review, we present successful strain mutagenesis and rational metabolic engineering examples leading to the construction of recombinant bacterial strains for the production of amino acids such as L‐glutamate, L‐lysine, L‐threonine and their derivatives from methanol as sole carbon s...