title: Native fluorescence and excitation spectroscopic changes in Bacillus subtilis and Staphylococcus aureus bacteria subjected to conditions of starvation.
abstract: Fluorescence emission and excitation spectra were measured over a 7-day period for Bacillus subtilis (Bs), a spore-forming, and Staphylococcus aureus (Sa), a nonspore-forming bacteria subjected to conditions of starvation. Initially, the Bs fluorescence was predominantly due to the amino acid tryptophan. Later, a fluorescence band with an emission peak at 410 nm and excitation peak at 345 m, from dipicolinic acid, appeared. Dipicolinic acid is produced during spore formation and serves as a spectral signature for detection of spores. The intensity of the 410-nm band continued to increase over the next 3 days. The Sa fluorescence was predominantly from tryptophan and did not change over time. In 6 of the 17 Bs specimens studied, an additional band appeared with a weak emission peak at 460 cm and excitation peaks at 250, 270, and 400 nm. The addition of beta-hydroxybutyric acid to the Bs or the Sa cultures resulted in a two-order of magnitude increase in the 460-nm emission. The addition of Fe2+ quenched the 460 emission, indicating that a source of the 460-nm emission was a siderophore produced by the bacteria. We demonstrate that optical spectroscopy-based instrumentation can detect bacterial spores in real time.
authors.affiliation: Institute for Ultrafast Spectroscopy and Lasers, The City College of New York, Convent Avenue and 137th Street, New York, New York 10031, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Alimova
authors.forename: Alvin
authors.initials: A
authors.lastname: Katz
authors.forename: Howard E
authors.initials: HE
authors.lastname: Savage
authors.forename: Mahendra
authors.initials: M
authors.lastname: Shah
authors.forename: Glenn
authors.initials: G
authors.lastname: Minko
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Will
authors.forename: Richard B
authors.initials: RB
authors.lastname: Rosen
authors.forename: Steven A
authors.initials: SA
authors.lastname: McCormick
authors.forename: Robert R
authors.initials: RR
authors.lastname: Alfano
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000494:pharmacology; D001412:Bacillus subtilis / Q000737:chemistry / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism; D003470:Culture Media / Q000494:pharmacology; D007501:Iron / Q000494:pharmacology; D010848:Picolinic Acids / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism; D013045:Species Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013171:Spores, Bacterial / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000737:chemistry / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism; D013217:Starvation / Q000139:chemically induced / Q000378:metabolism*; D014364:Tryptophan / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D003470:Culture Media; D010848:Picolinic Acids; D017262:Siderophores; D014364:Tryptophan; D007501:Iron; D020155:3-Hydroxybutyric Acid; C004860:dipicolinic acid