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.

The Social Life of Aeromonas through Biofilm and Quorum Sensing Systems

“…First, bacterial sessile life is associated with an increased persistence and resistance to stressful conditions including salinity, antimicrobial substances, or oxidative stress, compared to the planktonic lifestyle (Van Acker et al, 2014). Second, biofilms provide cell nutrients in higher concentrations than the surrounding environment via the nutrient-rich solute retained in the interstitial region of the extracellular polymeric matrix (Tsuchiya et al, 2009, 2016). …”

Manganese Oxide Biomineralization Provides Protection against Nitrite Toxicity in a Cell-Density-Dependent Manner

“…In biofilms, where diffusion is inhibited, oxygen is shown to rapidly diminish (63–65), which can favor anaerobic metabolism, including nitrate respiration to nitrite (66). Furthermore, biofilms are shown to preferentially select for and accumulate ions such as phosphate and nitrite (67–69). For example, in freshwater lake biofilms, the annual variation range for nitrite was found to be in the range of μM to mM (i.e., 1,000-fold) in biofilms (68).…”