2 research outputs found
Stimulative effect of lactic acid bacteria in the growth of the microalgae Isochrysis galbana
Objective: To study the effect of species of lactic acid bacteria (LAB) from telluric origin on
the growth of the microalgae Isochrysis galbana (I. galbana) in small and medium volume
flasks.
Methods: In the first experiment, 7 LAB species [Carnobacterium piscicola, Lactobacillus
brevis, Lactobacillus casei ssp. casei, Lactobacillus helveticus, Lactococcus lactis spp.
lactis, Leuconostoc mesenteroides spp. mesenteroides (L. mesenteroides spp. mesenteroides)
and Pediococcus acidilactici (P. acidilactici)] were inoculated in 250 mL flasks containing
microalgae I. galbana (106
cells/mL). After fitting the growth data to two mathematical models,
two LAB strains (L. mesenteroides spp. mesenteroides and P. acidilactici) were selected for
the second experiment in which those strains were inoculated in medium size (5 L) volume
cultures of I. galbana (1.2 × 105
–1.5 × 105 cells/mL). The bacterial load in cultures from the
first experiment was analyzed by plating on marine agar, MRS agar and thiosulfate citrate bile
saltssucrose media.
Results: All strains of LAB tested enhanced the growth rate and the final biomass yield of I.
galbana cultures, even in the absence of nutrients in the media. The best overall results and
the maximal final cell densities in small flasks were achieved with strains L. mesenteroides
spp. mesenteroides and P. acidilactici, respectively. These two strains also stimulated the
growth (40% and 16% with respect to controls) of I. galbana in medium size volumes. For
most strains, CFU values of LAB remained stable (105
–108 CFU/mL) for at least 4 days. A
high variability was observed in bacteria strains among treatments, with Pseudomonas and
Moraxella being the most abundant bacteria.
Conclusions: The results of present study showed that the growth of I. galbana in both small
and medium size volumes was enhanced by LAB, both in the absence and the presence of
nutrients in the culture. The highest final biomass was achieved by adding P. acidilactici,
whereas Carnobacterium piscicola and L. mesenteroides spp. mesenteroides provided maximal
growth rates. The former also showed an inhibitory effect on Moraxella