I n order to increase the availability of the cell bound protein in Scenedesmus algae, mechanical, enzymatic, and chemical methods of degrading the cell wall structure were investigated.The algae suspension together with glass beads was milled in a water-cooled chamber equipped with rotating disks. The enzyme tested was a cellulolytic enzyme (Meicelase) and the chemical employed was hydrogen peroxide.I n the ball-mill experiments a complete disintegration was achieved in a disintegrator, working with batches. Trials were also performed with a continuous disintegrator and the dependence of disintegration on bead size and flow rate was studied. The disintegration determined by microscopic cell count was compared to the increase of the pepsin digestibility.The Meicelase treatment caused a slight increase of the pepsin digestibility, as measured after 3 hr pepsin incubation. No increase of the pepsin digestibility could be detected with hydrogen peroxide treatment.After the ball-mill disintegration 95% of contaminating bacteria were killed and yields of extractable proteins were higher. The capacity of available continuous ball-mills is such that they could be used on a pilobplant scale and the energy cost of disintegration would be of the same magnitude as that of separation.Mechanical treatment involved the use of a ball-mill.

Fatty acids from Chlorella vulgaris, Scenedesmus obliquus var. acutus and from a mixed culture of the two strains, Melnik, were converted to methyl esters, separated by gas chromatography, and identified by means of standards. The spectrum of fatty acids included both saturated and unsaturated acids (with odd and even numbers of carbon atoms) from C12 to C22. Fatty acids C16:0, C18:0 and C20:3 were the major components in all cultures. Pure strains differed from the mixed culture in the production of C18:1, C12:0 and C19:2 acids; the first of these was present in higher amounts in pure cultures only, the latter two being found in the mixed culture. The level of lipids was lower as compared to the literature data and their extractability was affected by the manner of preparation of algae and extraction conditions.

No abstract

The COz mass balance for a suspension of algae cultivated in the region of neutral pH of the suspension on an open cultivation surface with a flowing suspension was assessed. From this balance an analytical expression for the course of free COZ dissolved in the suspension along the flow of the suspension is obtained. Relations for the rate of COZ decrease in the suspension and the ritilization of COz supplied to the cultivation surface are derived.

No abstract

Xummary:The algae were cultivated in an outdoor cultivation unit in waste water from sewage treatment plant processing city sewage and largescale hoggery effluent.The cultivation area (2 m*) had a slant of 3% and the suspension layer thickness was about 5 cm.The total suspension volume in the cultivation device was 150 1. Mass balance served us for derivation of formulas for the average rate of algal biomass production and for the extent of nutrient removal from waste water. Experiments showed a considerable effect of dilution rate on individual parameters in these formulas. The removal of nitrogen and phosphorus is optimal a t a dilutionrate of 0.3 day-1 whereas optimum biomass production lies a t about 0.1 day+. The nitrogen and phosphorus yield coefficient Y (g biomass/g element) are practically identical, both of them depending on dilution rate. The effect of the dilution rate on other characteristics of the effluent water has not yet been unambiguously proved. The results are shown of bacteriological and mycological examinations, in addition, of the chemical analysis of resulting algal biomass.

Chlorella kessleri cultivated in a deep tank contained 4.8% of non-polar lipid; 51% of this fraction represents saturated fatty acids, 7% unsaturated fatty acids. Our investigation of the fatty acids profile demonstrated even- and odd-numbered saturated and unsaturated fatty acids ranging from C12 to C20. Unlike in other Chlorella species, stearic acid was the dominant fatty acid found. Also shown was an elevated C16:0 fatty acid content and a reduced level of unsaturated fatty acids.