3.1. Microalgal growth and kinetic growth parameters
Cultivation of microalgae and cyanobacteria in single and dualspecies
cultures has shown significant influence on microalgal
growth. Fig. 1 represents the growth curves obtained for single
cultures of the studied microorganisms (A) and for dual-species
cultures containing S. salina (B). Typical growth curves obtained
when growing microalgae in batch conditions are very similar to
those observed for bacterial growth, which consist of six different
growth stages (Barsanti and Gualtieri, 2006; Monod, 1949): (i)
adaptation or lag phase; (ii) acceleration phase; (iii) exponential
or log phase; (iv) retardation phase; (v) stationary phase; and
(vi) declining phase. In the growth curves presented in Fig. 1, it
is possible to distinguish the adaptation phase, which lasted for
approximately one day for all studied cultures, and the exponential
growth phase. Regarding single cultures, the studied microalgae
and cyanobacteria have shown a similar growth behaviour,
reaching similar maximum biomass concentration values (approximately
(21.7 ± 3.3) 106 cells mL1). However, looking at the
growth curves obtained for the three studied consortia, it is possible
to see a significant increase (p < 0.05) in maximum biomass
concentrations achieved in the consortia SC and SM (approximately
(41.3 ± 3.3) 106 cells mL1). The consortium SP has
shown a similar behaviour to those observed for single cultures.
Higher biomass concentrations achieved in the consortia SC and
SM suggest a symbiotic relationship between these microorganisms
(Reyna-Martínez et al., 2014).