title: Freeze-dried recombinant bacteria for on-site detection of phenolic compounds by color change.
abstract: We herein report the development of a recombinant bacterial biosensor for the rapid and easy detection of phenolic compounds in the field. A plasmid was designed to encode a beta-galactosidase reporter gene under the control of capR, an activator involved in phenolic compound degradation. The construct was transformed into Escherichia coli, and transformed cells were stored after being freeze-dried in the presence of sucrose. For detection of phenolic compounds, the cells were rehydrated, and used instantly, without any growth step. In the presence of 0.1 microM-10mM phenol, we observed a red color from hydrolysis of chlorophenol red beta-D-galactopyranoside (CPRG) or an indigo color from hydrolysis of X-galactopyranoside (X-gal). Other phenolic compounds could be detected by this system, including catechol, 2-methylphenol, 2-chlorophenol, 3-methylphenol, 2-nitrophenol, and 4-chlorophenol. These results suggest that this novel bacteria biosensor may be useful for easy, on-site detection of phenolic compounds without the need for unwieldy equipment or sample pretreatment. Indeed, biosensor systems involving beta-galactosidase-expressing freeze-dried recombinant bacteria could prove useful for the in situ detection of many more compounds in the future.
authors.affiliation: Environmental Engineering Major, Division of Applied Bioengineering, Dongseo University, Busan 617-716, Republic of Korea. hjshin@dongseo.ac.kr
authors.forename: Hae Ja
authors.initials: HJ
authors.lastname: Shin
authors.forename: Hoo Hwi
authors.initials: HH
authors.lastname: Park
authors.forename: Woon Ki
authors.initials: WK
authors.lastname: Lim
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002733:Chlorophenols / Q000032:analysis / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005612:Freeze Drying; D005697:Galactosides / Q000032:analysis / Q000378:metabolism; D017930:Genes, Reporter; D005818:Genetic Engineering / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000378:metabolism; D010636:Phenols / Q000032:analysis*; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D012989:Soil Pollutants / Q000032:analysis; D014866:Waste Products / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D002733:Chlorophenols; D005697:Galactosides; D007211:Indoles; D010636:Phenols; D011994:Recombinant Proteins; D012989:Soil Pollutants; D014866:Waste Products; D014874:Water Pollutants, Chemical; C074184:chlorophenol red galactopyranoside; D001616:beta-Galactosidase; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside