Page 56 - Aquauclature Research and Studies (01)

AQUAUCLATURE
Research and Studies 1 (1): 15-01, 2026 page of 193
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determined, which mainly depended on inoculum sizes, culture conditions,
and growth medium components (Jayasankar and Valsala, 2008; El-kassas et
al., 2016). Growth assessment, represented by biomass and biochemical anal-
ysis of algae, are two key features for assessing the potential use of a prom-
ising candidate species for various applications (Arauĵo and Garcia, 2005; El-
kassas et al., 2016) for Chorella spp. and their applications in northern ocean
fish nutrition (Ashour et al., 2019). In this study, northern ocean fishes started
their stationary growth phase during the 10th day of incubation, achieving the
highest biomass value using fructose medium (A), followed by rumen fluid
(RL), while lactose (B) achieved the lowest biomass value. Similar studies
using the same carbon sources by Velu et al. (2015) revealed that biomass
production and lipid content were significantly increased with fructose com-
pared to the control group. Low glucose supplementation (0.5–1.0 g/L) sig-
nificantly enhanced chlorophyll synthesis and protein availability per culture
unit, but reduced the amount of lipids per unit of dry weight of biomass under
light conditions, while the addition of excess glucose concentrations (4, 8, or
16 g/L) resulted in a light-yellow color (Chai et al. (2018)). They also demon-
strated that high fructose concentrations resulted in a green-colored culture,
and this observation is consistent with our current study, where low glucose
concentrations of 0.5 g/L in light reduced biomass and green pigment, while
the same fructose supplementation increased the green appearance and bio-
mass content, while the addition of lactose caused little change in pigment
contents. In this regard, glucose may have stimulated the rapid growth of the
algae because it is a simple sugar and can be easily converted to produce ac-
etyl-CoA, which was then used in multiple pathways, including fatty acid
synthesis. Glucose and fructose had the same number of carbon numbers;
which were degraded by Various enzymes. Glucose is converted to glucose-
6-phosphate, a major catalytic product involved in both the glycolysis and
pentose-phosphate cycles (Stewart, 1974). However, fructose cannot be di-
rectly converted to glucose-6-phosphate in microalgae. As a result, the
growth rate was slightly reduced when fructose was used as the carbon source
compared to glucose. Similarly, in our experiment, the tested microalgae N.
oceanica showed high lipid accumulation in the order of glucose and fructose,