The Effect of Salinity and Light Intensity on the Batch Cultured Cyanobacteria Anabaena sp. and Cyanothece sp.

Abstract

On the quest of discovering novel local strains of microalgal species that can be effectively cultured with industrial perspectives, two cyanobacterial strains Anabaena sp. and Cyanothece sp. were isolated from the lagoonal and saltworks waters of the Messolonghi lagoon (W. Greece). They were batch cultured at 20–21.5 °C in six combinations of three salinities (20, 40 and 60 ppt) and two light intensities (2000 and 8000 lux) resulting in: (a) Anabaena grew best at 20 and 40 ppt at high light of 8000 lux. (b) Cyanothece grew best at 40 and 60 ppt at high light. (c) Low light of 2000 lux resulted in much reduced growth in all treatments. (d) Maximal biomass yield was 1.27 and 1.77 g d.w./L for Anabaena and Cyanothece, respectively. Overall, both species have culture potential yielding biomass comparable to the average (or above) relevant values reported in the literature for various cultured cyanobacteria.

In Vivo Absorption Spectra as Predictors of Algal Biomass and Pigment Content of the Cultured Microalgae Amphidinium carterae, Isochrysis galbana, Nephroselmis sp. and Anabaena sp.

“…While the correlations between dry weight and 750 nm and between chlorophyll-a or total carotenoids and 750 nm with pooled values for both intensities show a very strong relationship with an apparent predictive value, in the case of phycocyanin such a strong correlation is shown only when the correlation of phycocyanin-750 nm is applied separately for the spectral values of each light intensity. The results on the effects of illumination on cyanobacteria in recent works [21,26,27] can also be seen as confirming this phenomenon although culture parameters (light, temperature, salinity, aeration, pH) have a significant effect on cell growth of a given microalgal species and the same is true for pigment content [24,[29][30][31], this should not deter researchers from exploring the predictive potential of absorption spectra. However, this should be done only after sufficient time and effort has been invested in the basic biochemical studies in the culture of an algae under conditions found to be suitable so that they can be recorded as reference values in the respective environments.…”

Quantity and Quality of Light on Growth and Pigment Content of Dunaliella sp. and Anabaena sp. Cultures and the Use of Their Absorption Spectra as a Proxy Method for Assessment

“…Instead, the wavelength of 750 nm can reliably predict with sufficient accuracy algal density [54,56,[65][66][67][68][69][70] because this wavelength avoids the light absorption by photosynthetic pigments which might affect its absorbance value created by turbidity alone [48,56,71]. In both species of microalgae studied, its correlation with the algal density gave very high correlation coefficients and, as this was found also in my previous studies [45][46][47]55,56], leaves me with no doubt for its usefulness in the daily monitoring routine of an algal culture. Further on, when I correlated 750 nm with each pigment content, again, strong correlations ensued, and as I did not find any mention of such a relation in the literature, the present findings add novel knowledge.…”

“…As a tool for this purpose, it is shown that the absorption spectrum can give a reliable picture of the state of biomass and pigments from a qualitative and quantitative point of view, on the one hand, and, on the other hand, supply the observer with the values of the optical density of the peaks of the wavelengths that characterize each pigment type as well as the value at 750 nm where no algae pigment absorbs. Key to the applicability of the findings of the present study is the use of the 750 nm wavelength as a predictor of both algal density and photosynthetic pigments [45][46][47][54][55][56]. It is well known that the optical density (OD), also known as absorbance or turbidity, of several unicellular algae species and other unicellular microbes, is widely employed as a quick and nondestructive assessment of biomass [48,57], as the relationship between the amount of light absorbed by a suspension of cells and their mass or number is dependent on the size, shape and refractive index of the particles [58].…”

“…Dry weight was calculated by filtering a known amount of culture through 0.45 µm GF/C filters in a vacuum pump (Heto-SUE-3Q). The filters were next washed with ammonium formate to remove salts and then placed in an oven at 100 • C for 2 h [45][46][47].…”

Optimization of Industrial-Scale Cultivation Conditions to Enhance the Nutritional Composition of Nontoxic Cyanobacterium Leptolyngbya sp. KIOST-1

“…Although Leptolyngbya sp. KIOST-1 required time to adapt to the high-salinity conditions, similar to other cyanobacterium species [45], it was able to achieve a maximum biomass concentration at up to 50 psu salinity. Species with these characteristics are advantageous for biomass production.…”