title: INTERCOLONIAL VARIABILITY IN MACROMOLECULAR COMPOSITION IN P-STARVED AND P-REPLETE SCENEDESMUS POPULATIONS REVEALED BY INFRARED MICROSPECTROSCOPY(1).
abstract: Macromolecular variability in microalgal populations subject to different nutrient environments was investigated, using the chlorophyte alga Scenedesmus quadricauda (Turpin) Bréb. as a model organism. The large size of the four-cell coenobia in the strain used in this study (∼35 μm diameter) conveniently allowed high quality spectra to be obtained from individual coenobia using a laboratory-based Fourier transform infrared (FTIR) microscope with a conventional globar source of IR. By drawing sizable subpopulations of coenobia from two Scenedesmus cultures grown under either nutrient-replete or P-starved conditions, the population variability in macromolecular composition, and the effects of nutrient change upon this, could be estimated. On average, P-starved coenobia had higher carbohydrate and lower protein absorbance compared with P-replete coenobia. These parameters varied between coenobia with histograms of the ratio of absorbance of the largest protein and carbohydrate bands being Gaussian distributed. Distributions for the P-replete and P-starved subpopulations were nonoverlapping, with the difference in mean ratios for the two populations being statistically significant. Greater variance was observed in the P-starved subpopulation. In addition, multivariate models were developed using the spectral data, which could accurately predict the nutrient status of an independent individual coenobium, based on its FTIR spectrum. Partial least squares discriminant analysis (PLS-DA) was a better prediction method compared with soft independent modeling by class analogy (SIMCA).
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaSchool of Biological Sciences, Monash University, 3800 Victoria, Australia Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaCentre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia.
authors.forename: Philip
authors.initials: P
authors.lastname: Heraud
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaSchool of Biological Sciences, Monash University, 3800 Victoria, Australia Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaCentre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia.
authors.forename: Slobodanka
authors.initials: S
authors.lastname: Stojkovic
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaSchool of Biological Sciences, Monash University, 3800 Victoria, Australia Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaCentre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Beardall
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaSchool of Biological Sciences, Monash University, 3800 Victoria, Australia Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaCentre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia.
authors.forename: Don
authors.initials: D
authors.lastname: McNaughton
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaSchool of Biological Sciences, Monash University, 3800 Victoria, Australia Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia School of Biological Sciences, Monash University, 3800 Victoria, AustraliaCentre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia.
authors.forename: Bayden R
authors.initials: BR
authors.lastname: Wood
keywords: FTIR spectroscopy; Scenedesmus; macromolecular composition; nutrient limitation; population variability