No abstract

Microalgal culture is a key procedure in marine fish hatcheries, but this activity is far from optimized and has several problems remain to be solved. Nannochloropsis oculata are important to live feed organisms, which are used to rear the larvae of marine finfish. N. oculata were cultivated in tubular PBR and FRP panel PBR in a greenhouse. Tubular PBR was reached 701.7 x 106 cells mL-1 as its maximum cell density and FRP panel PBR was reached 245 x 106 cells mL-1 as maximum. Also, estimated maximum dry weights of tubular and FRP panel PBRs were calculated as 3.249 g L-1 and 1.47 g L-1, respectively. Consequently, tubular PBR was showed that it is more efficient than FRP panel PBR in this study.

Microalgae are used in aquaculture and various industrial fields such as pharmaceuticals, feed, food, agriculture, and energy. Microalgae is a potential natural food coloring agent as pigments and contain bioactive components such as polyunsaturated fatty acids (PUFA) in their composition. Porphyridium cruentum is a red alga with the ability to accumulate valuable pigments biomolecules such as phycoerythrin (PE), chlorophyll, and other carotenoids. In this study, P. cruentum was cultured for 51 days at the indoor pilot scale tubular photobioreactor (PBR). The highest cell number was 31.84 x 106 cells mL-1 and the highest specific growth rate was determined as 0.80. Total phycobiliprotein and phycoerythrin amounts were reached 0.252 ± 0.009 mg mL-1 and 0.224 ± 0.007 mg mL-1 at the early exponential phase, respectively.

Inositols are used as growth promoting agents over plants. But microalgae are different from higher plant especially photosynthetic efficiency and productivity. According to the results of this study, myo-inositol addition to the culture medium of Nannochloropsis oculata provides higher cell densities. 100 mg L-1 myo-inositol added experimental group was reached to 1.42 fold cell mL-1, while the 500 mg L-1 myo-inositol added group was reached to 1.28 fold cell mL-1 than the control group. Mean chlorophyll a per cell amounts were calculated for experimental groups and control groups as 0.052 pg cell-1 and 0.053 pg cell-1, respectively. Mean total carotene per cell amounts were calculated for all groups as 0.016 pg cell-1. These results show that no difference was occurred between all groups by chlorophyll a and total carotene amounts per cell. This study shows that myo-inositol use in microalgae production may provide higher yields.

In this study, the antibacterial activity of methanol and acetone extracts of Chlorella sp. was examined. The chemical contents of the extracts were clarified by GC/MS analysis. Antibacterial activity of Chlorella sp. extracts was determined as a minimum inhibitory concentration by broth microdilution method against Bacillus subtilis ATCC 6633, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213. It was found that methanol and acetone extracts of Chlorella sp. showed antibacterial activity against B. subtilis ATCC 6633 (625 µg/ml and 1250 µg/ml, respectively), E. faecalis ATCC 29212 (>5000 µg/ml and 1250 µg/ml, respectively), E. coli ATCC 25922 (>5000 µg/ml), P. aeruginosa ATCC 27853 (>5000 µg/ml), S. aureus ATCC 29213 (2500 µg/ml) at the specified concentrations. In the chemical analysis of the extracts, it was determined that the fatty acids were in high amounts, 33.22% and 40.41%, respectively, in the methanol and acetone extracts. Among the alternative methods to show activity against pathogenic microorganisms, algae can be a good natural resource. This study showed that Chlorella sp. contains high fatty acids and has potential as an antibacterial agent of natural origin.