Viability Of Microalgae Research Articles

Cyanobacteria and algae of buried soils and their modern analogues

Living green microalgae morphologically identified as Muriella terrestris and Heterochlorella luteo-viridis have been cultivated from buried soil samples of a Middle Sarmatian kurgan (1st Century AD.). Paleosols for which the algal flora has been studied have a microalgal pool with a substantially lower abundance and taxonomic diversity than modern humus horizons. We discuss the probable reasons for the preservation of microalgae viability in paleosols over a period of 200 years after their burial. The first find of the green alga Hemiflagellochloris kazakhstanica in Russia was discovered in fine solonchakous solonetz, buried approximately 40 years ago as result of plowing of the kurgan. The structures of algal-cyanobacterial assemblages of modern background soils are also considered.

Chip-Based Portable Device for Detection of Microalgae Viability in Ballast Water

Ship ballast water has been identified as one of four major environmental threats by the international maritime organization. This paper presents a portable on-site rapid detection system of microalgae in ship ballast water. The system consists of a microfluidic chip platform, LED light source and drive systems, optical detection system, ARM software and hardware system, power supply system and so on. Microalgae particles can go through the detection area inside the micro channels one by one by using a sheath fluid focus. The resulting chlorophyll fluorescence is converted to the electrical pulse signal by photodiode. The experimental results show that the system can quickly and accurately detect the ballast water living microalgae concentration. The minimum detectable microalgae size is about 3μm (mean diameter). This system has some advantages such as miniaturized, portable, fast, accurate and label free, and has great potential for on-site rapid detection of ship ballast water.

The effect of ultrasound on the growth and viability of microalgae cells

Ultrasound has shown potential for both increasing microalgal lipid extraction yields and for the control of microalgal blooms through cell disruption. The effect of ultrasound on the viability of microalgae was investigated on the following species: Dunaliella salina, Chlamydomonas concordia and Nannochloropsis oculata. Sonication with a 20 kHz probe (0.086 W cm−3) caused complete cell disruption of D. salina after 4 min. This microalgae species does not have a true cell wall. In the case of C. concordia which has a thin cell wall complete cell disruption under the same conditions took 16 min. Under the same conditions, there was no visible disruption of N. oculata, a species which has a thick cell wall. However spectro-fluorophotometer analysis of the sonicated suspension of N. oculata showed that although the cells were intact, the level of intracellular chlorophyll was reduced by ~10 %. This clearly indicated damage to the microalgal cell wall. After 16 min, treatment cultures of all three species remained viable. Programmed cell death (PCD) has been induced in some microalgal species to terminate algal blooms; ultrasonic application did not induce PCD in any species tested. The supernatant of sonicated D. salina and C. concordia has also been shown to be able to boost the growth of established cultures. These results provide important information concerning the uses of ultrasound in both the microalgal biofuels industry and for the control of microalgal blooms.

Fabrication of Environmentally Biodegradable Lignin Nanoparticles

We developed a method for the fabrication of novel biodegradable nanoparticles (NPs) from lignin which are apparently non-toxic for microalgae and yeast. We compare two alternative methods for the synthesis of lignin NPs which result in particles of very different stability upon change of pH. The first method is based on precipitation of low-sulfonated lignin from an ethylene glycol solution by using diluted acidic aqueous solutions, which yields lignin NPs that are stable over a wide range of pH. The second approach is based on the acidic precipitation of lignin from a high-pH aqueous solution which produces NPs stable only at low pH. Our study reveals that lignin NPs from the ethylene glycol-based precipitation contain densely packed lignin domains which explain the stability of the NPs even at high pH. We characterised the properties of the produced lignin NPs and determined their loading capacities with hydrophilic actives. The results suggest that these NPs are highly porous and consist of smaller lignin domains. Tests with microalgae like Chlamydomonas reinhardtii and yeast incubated in lignin NP dispersions indicated that these NPs lack measurable effect on the viability of these microorganisms. Such biodegradable and environmentally compatible NPs can find applications as drug delivery vehicles, stabilisers of cosmetic and pharmaceutical formulations, or in other areas where they may replace more expensive and potentially toxic nanomaterials.

Assessment of microalgae viability employing insulator-based dielectrophoresis

Microscale bioparticle analysis has advanced significantly providing advantages over bench-scale studies such as the use of a reduced amount of sample and reagents, higher sensitivity, faster response, and portability. Insulator-based dielectrophoresis (iDEP) is a microscale technique where particles are driven by polarization effects under a non-uniform electrical field created by the inclusion of insulators between two electrodes. iDEP possesses attractive advantages over traditional electrode-based dielectrophoresis since there is no electrode degradation and manufacture of the device is simpler and economical. This novel and powerful technique has been applied successfully in the manipulation of macromolecules and cells. In this study, differences in dielectric properties (cell membrane conductivity) of viable and non-viable microalgae, Selenastrum capricornutum, were employed to concentrate and separate a mixture of live and dead cells. A microchannel, manufactured in glass and containing an array of cylindrical insulating posts, was employed to dielectrophoretically immobilize and concentrate the mixture of cells employing direct current electric fields. Experiments showed that live cells exhibited a stronger dielectrophoretic response than dead cells, which allowed cell differentiation. Separation and enrichment of viable and non-viable microalgae was achieved in 35 s with a concentration yield of 10.36 and 15.87 times the initial cell concentration, respectively. These results demonstrate the use of iDEP as a technique for rapid assessment of microalgae viability; unveiling the potential of this powerful technique for environmental applications on lab-on-a-chip platforms.

PHOTOSYNTHETIC ACTIVITY AS A MEASURE OF VIABILITY IN MICROALGAE

The photosynthetic activity as measured by the light fixation of 14CO2 by intact cells has been shown to be a measure of viability of microalgae. This method can be conveniently employed to examine the cell viability change in non-growing systems. Comparative studies on heat and UV sensitivities of various algae were carried out using this method.