title: Importance of Selecting Appropriate Wavelength, While Quantifying Growth and Production of Quorum Sensing Regulated Pigments in Bacteria.
abstract: BACKGROUND
  Pigment production is regulated by quorum-sensing (QS) in certain bacteria which are being widely used as model organisms in different QS labs. This paper emphasizes importance of selecting an appropriate wavelength for quantification of bacterial growth and pigmentation. While screening different natural/synthetic preparations for their possible QSmodulating potential, it becomes very much necessary to establish that the observed effect is truly QS-associated, and not falsely inflated owing to inaccurate quantification of bacterial cell density/ pigment intensity.
  
  
  METHODS
  Pigments were extracted in suitable organic solvents, whereas quantification of bacterial growth and extracted pigments was done photometrically.
  
  
  RESULTS
  Findings reported in this paper, suggest that while quantifying cell density in a pigmented bacterial suspension, such a wavelength (e.g. 764 nm) should be selected at which pigment interference is either absent or minimum. Additionally, importance of appropriate dilution of the bacterial cell suspensions, prior to photometric measurement has been highlighted.
  
  
  CONCLUSIONS
  This work indicates that while working with pigmented bacteria, it is important to pay attention to the absorption spectrum of the pigment(s) involved, and also to dilute the dense bacterial suspensions appropriately prior to measuring optical density, so as to avoid any major deviation of OD from the proportionality to the cell density. Besides presenting the experimental data in this paper, patents regarding measurement of cell growth, as well as those indicating the potential of commercialization of various aspects of QS research have been mentioned.
authors.forename: Chinmayi
authors.initials: C
authors.lastname: Joshi
authors.affiliation: Institute of Science, Nirma University, Ahmedabad-382481, Gujarat, India. vijay.kothari@nirmauni.ac.in.
authors.forename: Vijay
authors.initials: V
authors.lastname: Kothari
authors.forename: Pooja
authors.initials: P
authors.lastname: Patel
mesh_terms: D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism*; D002452:Cell Count / Q000379:methods; D010330:Patents as Topic; D010860:Pigments, Biological / Q000378:metabolism*; D053038:Quorum Sensing / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D010860:Pigments, Biological