Avaliação do crescimento e rendimento em biomassa das diatomáceas Amphora sp., Chaetoceros calcitrans e Thalassiosira fluviatilis.

Abstract

Microalgae are autotrophic microscopic organisms that form a heterogeneous group, predominant in aquatic environments, responsible for most of the oxygen and primary production of the Earth. They are classified into four main groups: Cyanophyceae, Chrysophyceae, Chlorophyceae and Bacillariophyceae (diatoms). These microorganisms produce various organic compounds and are commonly used in several branches of industry and aquaculture. The present study aimed to evaluate the growth and yield in dry biomass of the diatoms: Amphora sp., Chaetoceros calcitrans and Thalassiosira fluviatilis. The experimental design was completely randomized, with three replications for each species, totalling nine experimental units. For growth evaluation, daily counts were performed in a Neubauer chamber and optical microscope, obtaining the variables: growth rate (K), doubling time (DT) and maximum cell density (MCD). Likewise, growth curves were drawn up adjusted by approximating the logistic curve. At the end of the cultivation, the dry biomass yield was obtained, after the centrifugation steps, to remove the supernatant and lyophilization, to dry the biomass. As a result, higher DCM and K were obtained for C. calcitrans (1,225 x 104 cells mL-1 and 1.58 div day-1) and higher dry biomass yields for T. fluviatilis (0.61 g L-1) and Amphora sp. (0.46 g L-1). The three species showed different parameters of growth and yield in biomass, being T. fluviatilis and Amphora sp. favorable for yield in dry biomass and C. calcitrans to reach higher cell densities.