Transitional-state growth kinetics of Thalassiosira pseudonana (Bacillariophyceae) during self-shading in batch culture under light-limiting, nutrient-replete conditions: Improving biomass for productivity (culture quality)

Abstract

Batch culture is the most common method for microbial cultivation, of which its growth dynamics is classified into distinct phases. Importantly is the phase of declining growth (but known as the “linear growth phase” during shade-limited growth for algae) that follows exponential growth and precedes the stationary growth phases. During this phase, under nutrient-replete and light (shade)-limiting conditions, an increasing algal biomass occurs concurrent with a decreasing growth rate (culture quality) that is historically thought to generate a peak of maximum productivity. Dense batch cultures (to >2g dry weightl−1) of the marine diatom Thalassiosira pseudonana were grown under a range of incident scalar irradiances (2–26Einm−2d−1) using both continuous light and 12-h day length in an integrated light environment. Under these conditions, a light-limiting, transition-state dynamic phase between exponential and stationary growth was examined. Growth rate varied to the power of biomass during the phase of linear growth. As a consequence, maximum productivity was provided a broad plateau, not a peak, throughout this phase as a function of incident irradiance, during which culture quality changed, and needs consideration in the engineering, design, and operation of mass algal cultivation systems.