Application of an incomplete factorial design for the formation of an autotrophic biofilm on river bed sediments at a microcosms scale

作者：Devesa Rey Rosa^*; Moldes Ana B; Sanmartin Patricia; Prieto Fernandez Angeles; Barral Maria T

来源：Journal of Soils and Sediments, 2010, 10(8): 1623-1632.

DOI：10.1007/s11368-010-0289-0

• Biofilm
• Carbohydrate
• Chlorophyll a
• EPS
• Factorial design

River bed sediments are often colonized by microorganisms which can produce large amounts of extracellular polymeric substances (EPS) forming biofilms that may increase the resistance of the bed sediment towards erosion and affect the nutrient and pollutant exchange between water and sediments. The objective of this work was to study the influence of organic carbon, ionic concentration (NaCl) and N/P ratio on the growth of autochthonous biomass and the production of EPS in autotrophic biofilms by measuring the extracellular carbohydrates produced, a specific component of the EPS.
For this purpose, an incomplete 3(3) factorial design was carried out to study the influence of the ionic concentration, ranging between 0 and 25 mg/l NaCl; organic carbon concentration, ranging between 0 and 10 mg/l glucose and N/P ratio, ranging between 5 and 20, on the following dependent variables: chlorophyll a and carbohydrate concentration at a microcosms laboratory scale. Heterotrophic density was also included as a third dependent variable.
The ionic and carbon concentrations in the ranged tested were the most influential variables in the production of carbohydrates and chlorophyll a. The biofilm formation was stimulated in a medium with a 1:5 ratio for N/P and 10 mg/l of glucose and 25 mg/l of ionic concentration. The extracellular concentration of carbohydrates increased in parallel with the accumulation of chlorophyll a, which suggests that the autotrophic biomass may be an important component for the biofilm formation.
This work demonstrates that it is possible to develop empirical models that describe the interrelationship between organic carbon, ionic concentration (NaCl) and N/P ratio and the extracellular carbohydrates as well as chlorophyll a, contained in the biofilm developed over river bed sediments. It can be concluded that concentrations of 25 mg/l of NaCl and 10 mg/l of carbon improve the biofilm formation from river bed sediments, whereas N/P ratio higher than 5 produced a negative effect in the production of carbohydrates and chlorophyll a and consequently in the production of biofilm.

• 出版日期2010-12