Modified bacterial strains for improved fixation of nitrogen
Inventors
Temme, Karsten • Shah, Neal • Ozaydin Eskiyenenturk, Bilge • BLOCH, Sarah • Tamsir, Alvin
Assignees
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Publication Number
US-12643837-B2
Publication Date
2026-06-02
Expiration Date
Abstract
Methods and systems are provided for generating and utilizing a genetically engineered bacterium comprising a modification in a gene regulating nitrogen fixation or assimilation, wherein the modification in the gene regulating nitrogen fixation or assimilation results in one or more of: constitutive expression of a nifA gene in nitrogen limiting and non-nitrogen limiting conditions, activity of nifA in non-nitrogen limiting conditions, decreased uridylyl-transferase activity of GlnD, decreased adenylyl-removing activity of GlnE, and increased ammonium excretion.
Core Innovation
The disclosure describes genetically engineered Klebsiella variicola and Kosakonia sacchari bacteria comprising genetic modifications in genes regulating nitrogen fixation or assimilation, including deletions in nifL, glnD, and glnE. These genetic modifications enable nitrogen fixation in the presence of exogenous nitrogen and increase ammonium excretion. A disclosed method contacts a plant, plant part, or soil with the engineered bacteria to increase atmospheric-derived nitrogen in the plant.
The engineered bacteria function under nitrogen-replete conditions and oxygenated soil, colonizing roots and demonstrating nitrogenase activity. Compositions comprise these engineered bacteria, including designated strains deposited under ATCC Accession Nos. PTA-126740 and PTA-126743. Evaluations document increased shoot biomass, plant nitrogen, crop fresh weight, and positive yield trends in field trials.
Claims Coverage
The claims identify three independent claims directed to three inventive features comprising a plant treatment method and two composition embodiments.
Increasing atmospheric-derived nitrogen in a plant
A method comprising contacting a plant, a part of a plant, or soil into which the plant is planted with genetically engineered Klebsiella variicola and Kosakonia sacchari bacteria to increase atmospheric-derived nitrogen in the plant, wherein the bacteria comprise genetic modifications in genes regulating nitrogen fixation or assimilation; [procedural detail omitted for safety].
Composition of genetically engineered bacteria
A composition comprising genetically engineered Klebsiella variicola and Kosakonia sacchari bacteria, each comprising genetic modifications in genes regulating nitrogen fixation or assimilation, including specified deletions in nifL, glnD, and glnE; [procedural detail omitted for safety].
Microbial composition comprising deposited strains
A microbial composition comprising a Kosakonia sacchari bacterium represented by ATCC Accession No. PTA-126743 and a Klebsiella variicola bacterium represented by ATCC Accession No. PTA-126740.
The independent claims cover a plant-contacting method for increasing atmospheric-derived nitrogen, a bacterial composition comprising specified nitrogen-regulatory modifications, and a microbial composition comprising two designated deposited strains.
Stated Advantages
The engineered bacteria enable nitrogen fixation in the presence of exogenous nitrogen and increase ammonium excretion.
The method is directed to increasing the amount of atmospheric-derived nitrogen in a plant.
The strains increase corn shoot biomass and plant nitrogen incorporation.
Strain ATCC PTA-126740 and the strain combination exhibit modest positive yield trends and yield stability in multi-location field trials.
The bacterial combination yields greater fresh weight than untreated controls in tested crops, while remaining below the nitrogen-fertilized check.
The bacterial strains exhibit greater bioreactor biomass than uninoculated controls.
Drawing-sheet summaries report improved predicted nitrogen production across strain-development features.
Documented Applications
Treatment of plants, plant parts, or planting soil with genetically engineered Klebsiella variicola and Kosakonia sacchari bacteria to increase atmospheric-derived nitrogen in the plant.
Microbial compositions containing genetically engineered Klebsiella variicola and Kosakonia sacchari bacteria, including compositions comprising the strains represented by ATCC Accession Nos. PTA-126740 and PTA-126743.
Agricultural formulations and treatments for crops, including documented use with corn, association with plant tissues such as roots, and experimental evaluations assessing crop yield and fresh weight.
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