Local strains of chiorella vulgaria, C. pyrenoidosa **cenedeumus quadricauda and chiamydomonas debaryana were studies under controlled aseptic conditions with a view to determine their growth characteristics and efficiencies of protein production. Optimization or physical and chemical environment was achieved for the purpose or getting the maximum yield of protein. The effort of nitrogen concentration, N / P ratio, illumination and temperature on specific growth rate (k) and protein content of the algae was studies, in nitrogen concentration studies two nitrogen source (KNO3 and urea) were employed for assessing the effect of N source on k and k and protein turn over of the algal straine.
C. vulgaris, C. pyrenoidosa , *. Quadricauda and chlamydomonas debgaryane gave their k maxima (0.283, 0.685, 0.702) at 40, 55, 50 and 45 mg/I N concentration respectively. A wide range of N concentrations (5 mg/I to 2000 mg/I was in used order to determine the tolerance of the algal strains for nitrogen. Using Kno3 as nitrogen source the maximum nitrogen tolerance limit of C. vulgaris , was found to be at 700 mg/I N and in case of the other three strains this limit was found to be at 800 mg/I N. when using urea ** N. source the maximum N tolerance of C. vulgaris and chiamyqomonas qebaryana was found to be at 1100 mg/I N. While with *. Quadricauda and chlamyqomonas debaryana the *aid limit was observed to be 1000 mg/I N. The above data when exeminea to test the applicability of michaelie-menten equation, was not found to obey the said equation in the strict sense of the term thus showing that the nitrate reduction by algae was not a single step process but a multistep enzymic reaction.
The protein contents of the cell material of the algae grown in media with different nitrogen concentrations were determined and it was found that the celluar protein content and an almost direct relationship with the N concentration which held almost upto the maxitolerane limit of N contcentration beyond which the protein synthesis showed a decline. The highest protein yields recorded with C.vulgaria, decline. The highest protein yields recorded with C.vulgaria, C.pyrenoidosa, *.quadricauda and chlamydonoas debaryana were 44.71%, 52.59%, 47.45% respectively using KNO3 as the N source. When employing urea as N source the corresponding yields in the same order were 46.72%, 56.74% 51.75% and 59.57%, thus it is evident that urea gives better results in terms of K, N tolerance and protein synthesis and further it appears that relatively ****king chlamydomonas debaryana has the best culture characteristice in terms of k and protein yield.
The biological efficiencies of protein production of three algal strains (c.pyrenoidosa . *. Quadricauda and chlamydomoas debaryana) were determined by estimating their nitrate to protein conversion efficiencies (HPOE) which were expressed as the percentage of nitrate-N transformed to protein-N in a specified time period in the exponential phase of their growth and N-assimilation curves. The NPCE values for the algal strains were found to be in the range of 25.00 to 46.27 at 5000 lux and 37.2 to 53.0 10.000 lux. Thus NPCE was found to be enhanced by increase of illumination intensity and also by increase or N concentration chlamydomonas debaryana geve the best results, with *****cnoidosa and *. Quadricauda showing leaser efficiencies in their sequential order. The exptl. Algae wee found to possess fairly high nitrogen removal efficiencies. When ranged from 75.5 to 82.0. chlamydomonas debaryana exhibited the highest nitrogen removal efficiency.
N/P optima for the four experimental strains were found to be in a range of 15/1 to 25/1. chlorrlla vulgaris gave its k max (0.183) at N/P ratio of 15/1.C.pyrenoidosa gave its k max (0.544) at N/P ratio or 20/11 *.quadricauda gave its k max (0.659) at N/P ratio of 25/1 and chlamydomonas debaryana gave its k max (0.765) at N/P ratio or 20/1. All the four strains gave their highest protein yields (43.75%, 54.32%, 47.32% and 56.95% resecitvily) at N/P ratio of 50/1.
Effect of temperature on the growth characteristics and protein yields of the algae was studied by growing the algal cultures within the temperature range of 20 to 35oc. whereas C. vulgaria and C.pyrenoidosa gave their k maxima at 25oc, *. Quadricauda showed its best at 27oc and chlamydomonas debaryana exhibited the highest temperature adaptability by giving its k max at 29oc. c.vulgaria. c.pyrenoidosa and *.quadricauda gave their protein yield ***** (44.45%, 51.54% respectively) at 25oc while chlamydomonas debaryana gave its maximum protein yield (53.63%) at 27oc.
Incident illumination intensities of 3000 to 13000 lux (0.015 cals cm-2 min-1) were emplyes for studying the effect or illuminance upon the growth of , max. were 0.441, 0.981, 0.930 and 1.301 for c.vulgarias, c.pyrenoidosa, *. Quadricauda and chlamydomonas debaryana respectively. The saturation light intensities (Is) were found to be 0.045, 0.950, 0.055 and 0.50 respectively for the above mentioned algae. The protein yields obtained from found to vary from 49.64 (in case of c.vulgaris) to 61.37% (in case of chlamydomonas debar***).
Photosynthetic light energy conversion efficiencies (Eo) of the algae were determined in artificially illuminated and out-door sun-irradiated culture. Eo factor was found to be influenced by temperature. Intensity of illumination, quality of light. Nitrogen source and nature of the strain. Optimum values of Eo were obtained at 25oc when ranged from 0.054 to 0.144 for the different algal strains. Whereas the temperature of 22oc was found to be sub-optional for photosynthesis. A temperature of 35o was found to be positively harmful for the photosynthetic process resulting in a drastic reduction in the Eo values.
Chlamydomonas debaryana gave the highest Eo value at 25o (o.144) in the indoor cultures. Potassium nitrate and urea were employed as the two nitrogen sources and the latter was found to be superior with regard to Eo value of the algae. Effect of light quality on the photosynthetic efficiency was studies using two different light sources namely fluorescent tubes and incandescent bulbs. The Latter light source was found to be much inferior possibly due to the infrared and other pernicious radiations emitting from the said source. In the cultures (run in the month of May) the Eo values were found to be rather (0.0175 to 0.227) probably due to lack of turbulence and high intensity of illumination which could not be utilized efficiently by the stationary cultures. C.pyrecidose proved to be the best energy trapper in respect of Eo (0.0227) in outdoor experiments. In general the Eo values obtained for the experimental algae appeared to justify their economic exploitation for mass culture. On the basis of an average value of Eo (s.04) for a given algal strain , the scaling up of the culture would result in the annual per area production of 20 ‚€“ 30 tons of algal or 10 ‚€“ 15 tons of protein materials. These figures definitely establish the superior it of the algal culture over the conventional agriculture in which the highest protein products like *soyabeans could not give yields higher than 0.26 ton of protein per acre per year.
The nutritional value of the **** proteins was determined by estimating the biological availability of the essential amino acids after enzymic hydrolysis. The amino acid ***** were carried out by **** hicrobiological availability of the essential amino acid after enzymic hydrolysis. The amino acid assay were carried out Ford‚€™s microbiological method. The technique was used ** a view simulate the in-vivo conditions and thus giving a true picture of the nutritional grade of the **** proteins. The essential amino acids of the algal strains were found to constitute 20 ‚€“ 40% of the total cell proteins effects of enzyme concentration, heat pretreatment and ultrasonication of the cell material on the biological availability of the amino acids of the algae was studied. Two percent crude papain (1 mg/5 mg N ) was found to give better results. The heat pretreatment (at 11oc) was found to extract an adverse effect upon the nutritional value of the algal proteins. The ultrasonic disintegration of the cell mall was found to have beneficial upon the biological availability of amino acids.
The above mentioned results in general corroborated the results reported by Ford regarding the biological availability of essential amino acids of leaf proteins. The observed values of the biological availability of the algal amino acids were however, found to the rather low possibly due to the inefficiency of the enzyme (papain) to accomplish complete rupture of the cell walls of the algae.
Judged from above results it appeared that the algal species studied in the present work hold a good promise of economic exploitation in the local environmental conditions provided some suitable continuous culture plant could be designed in the light of these findings. This is a problem which could be tackled by the collaboration of algal microbiologists and chemical engineers. A project on these lines has already been started by the author in the division of biochemistry, chemistry department, University of Engineering and Technology, Lahore.