title: Analysis of Dissolved Organic Nutrients in the Interstitial Water of Natural Biofilms.
abstract: In biofilms, the matrix of extracellular polymeric substances (EPSs) retains water in the interstitial region of the EPS. This interstitial water is the ambient environment for microorganisms in the biofilms. The nutrient condition in the interstitial water may affect microbial activity in the biofilms. In the present study, we measured the concentrations of dissolved organic nutrients, i.e., saccharides and proteins, contained in the interstitial water of biofilms formed on the stones. We also analyzed the molecular weight distribution, chemical species, and availability to bacteria of some saccharides in the interstitial water. Colorimetric assays showed that the concentrations of saccharides and proteins in the biofilm interstitial water were significantly higher (ca. 750 times) than those in the surrounding lake waters (p < 0.05). Chromatographic analyses demonstrated that the saccharides in the interstitial waters were mainly of low molecular-weight saccharides such as glucose and maltose, while proteins in the interstitial water were high molecular-weight proteins (over 7000 Da). Bacterial growth and production of EPS occurred simultaneously with the decrease in the low molecular-weight saccharide concentrations when a small portion of biofilm suspension was inoculated to the collected interstitial water, suggesting that the dissolved saccharides in the interstitial water support bacterial growth and formation of biofilms.
authors.affiliation: College of Life Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Tsuchiya
authors.affiliation: College of Life Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Shima
authors.initials: S
authors.lastname: Eda
authors.affiliation: Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Chiho
authors.initials: C
authors.lastname: Kiriyama
authors.affiliation: Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Asada
authors.affiliation: College of Life Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan. morisaki@sk.ritsumei.ac.jp.|Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan. morisaki@sk.ritsumei.ac.jp.|Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga, 525-8577, Japan. morisaki@sk.ritsumei.ac.jp.
authors.forename: Hisao
authors.initials: H
authors.lastname: Morisaki
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000254:growth & development; D018441:Biofilms; D015169:Colony Count, Microbial; D005618:Fresh Water / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D011134:Polysaccharides / Q000032:analysis; D011506:Proteins / Q000032:analysis; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D011134:Polysaccharides; D011506:Proteins; D014867:Water
keywords: Biofilm; HPLC; Interstitial water; Saccharides; TLC