title: Color measurement as a means of quantifying surface biofouling.
abstract: Laboratory reactors fitted with removable ceramic porcelain growth surfaces were inoculated with a consortium of biofilm forming environmental isolates. A Minolta colorimeter CR-200 (Minolta Camera Co., Ltd, Ramsey, NJ) was used in conjunction with a specially designed adapter to evaluate the reflective color of the porcelain disks as biofilm accumulated on them. Areal viable cell counts were monitored over a period of eleven days in two separate experiments and direct color measurements of the untreated, microbially fouled test surfaces were collected. This colorimetric assay was both non-destructive and immediate. A strong linear relationship between log cell density and log color change was observed. The Pearson product moment correlation coefficient for all 45 observations combined was r = 0.95. Separate regression lines for each experiment were not significantly different (P = 0.19). When adjusted for time, the (partial) correlation coefficient between log cell density and log color change was r = 0.87, which suggests that the relationship between the two measures can not be explained by their mutual dependence on time. Reflective color measurement provided a rapid, non-destructive and quantitative measure of biofllm accumulation.
authors.affiliation: Center for Biofilm Engineering, Montana State University, Bozeman 59717, USA.
authors.forename: B
authors.initials: B
authors.lastname: Pitts
authors.forename: M A
authors.initials: MA
authors.lastname: Hamilton
authors.forename: G A
authors.initials: GA
authors.lastname: McFeters
authors.forename: P S
authors.initials: PS
authors.lastname: Stewart
authors.forename: A
authors.initials: A
authors.lastname: Willse
authors.forename: N
authors.initials: N
authors.lastname: Zelver
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002138:Calibration; D002516:Ceramics; D015169:Colony Count, Microbial; D003116:Color; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D004783:Environmental Microbiology; D005069:Evaluation Studies as Topic; D011549:Pseudomonas / Q000254:growth & development*; D014038:Toilet Facilities