title: A cad-gfpmut3 plasmid construct in Escherichia coli for gene induction-based quantification of lysine in acid hydrolysates of feedstuffs.
abstract: OBJECTIVE
  To generate an inducible plasmid-borne cad-gfpmut3 transcriptional fusion and develop a method for quantification of total lysine.
  
  
  RESULTS
  The cad-gfpmut3 transcriptional fusion was constructed by cloning the cad promoter (Pcad) upstream of a promotorless gfpmut3 located on a high-copy plasmid. The construct was electroporated into Escherichia coli ZK126 and the transformed strain was subsequently used to quantify lysine in feed ingredients. Lysine standard curves based on gene induction of the bacterial cells were used for estimating acid hydrolysate lysine concentrations in four feed ingredients. Except for sorghum, no substantial differences were observed when the data for lysine in soybean (2 x 49 +/- 0 x 37%), cottonseed (1 x 82 +/- 0 x 15%), and meat and bone meal (2 x 31 +/- 0 x 24%) generated by the newly developed construct were compared with previously published data.
  
  
  CONCLUSIONS
  Using the cad-gfpmut3 fusion, feed derived lysine induction was measured easily and accurately, and could be a useful tool for the estimation of lysine in acid hydrolysates of feed ingredients.
  
  
  CONCLUSIONS
  The described approach for lysine quantification in feed ingredients represents a cost- and time-efficient method offering rapid and accurate lysine quantification of multiple samples.
authors.affiliation: Department of Poultry Science, Texas A&M University, College Station, TX, USA.
authors.forename: V I
authors.initials: VI
authors.lastname: Chalova
authors.forename: C L
authors.initials: CL
authors.lastname: Woodward
authors.forename: S C
authors.initials: SC
authors.lastname: Ricke
mesh_terms: D000143:Acids / Q000737:chemistry; D026905:Amino Acid Transport Systems / Q000235:genetics*; D000821:Animal Feed / Q000032:analysis* / Q000382:microbiology; D000818:Animals; D017920:Antiporters / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics* / Q000378:metabolism; D006868:Hydrolysis; D008239:Lysine / Q000032:analysis* / Q000378:metabolism; D010957:Plasmids / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D000143:Acids; D026905:Amino Acid Transport Systems; D017920:Antiporters; C490242:CadB protein, E Coli; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D008239:Lysine