Iranian Scientific Fisheries Journal

fa مقاله علمی – پژوهشی:‌ مطالعه کمی و کیفی رشد ریز جلبک Chlorella vulgarisدر آب چاه ژرف سیستان Quantitative and qualitative study of the microalgae growth, Chlorella vulgaris in deep aquifer well water of Sistan تكثير و پرورش تكثير و پرورش پژوهشي Research در این مطالعه به بررسی کمی و کیفی رشد ریز جلبک Chlorella vulgaris در در محیط کشت گیلارد و آب ژرف منطقه سیستان پرداخته شده است. این آزمایش با 5 تیمار (تیمار 1: 100 درصد محیط کشت، تیمار 2: 25 درصد آب ژرف، تیمار 3: 50 درصد آب ژرف، تیمار 4: 75 درصد آب ژرف، تیمار 5: 100 درصد آب ژرف) و 3 تکرار طی مدت زمان 10 روز در دمای 27 درجه سانتی‌گراد و روشنایی 3500 لوکس و هوادهی به صورت مداوم در ظرف‌های 500 میلی لیتر انجام شد. نتایج این آزمایش نشان داد، pH در تیمارهای آب ژرف به میزان 63/10-89/8 بوده است. به‌علاوه، همه تیمارها نسبت به روز اول آزمایش (تراکم 104×15 سلول در میلی لیتر) تا روز 5 آزمایش از رشد برخوردار بودند و بعد از آن روند رشد آنها نزولی شد. نتایج نشان داد که در بین تیمارها، تیمار 2(25 درصد آب ژرف) از کمترین رشد 104× 24/50 سلول در میلی لیتر و تیمار 5 (100 درصد آب ژرف) با تراکم 104×33/129 سلول در میلی لیتر نسبت به سایر تیمارها دارای بیشترین رشد بود. بیشترین و کمترین نرخ رشد ویژه (SGR) به‌ترتیب برای تیمار یک (100 درصد محیط کشت) و 4 (75 درصد آب ژرف) بود. همچنین بیشترین و کمترین زمان دو برابر شدن (DT) به‌ترتیب مربوط تیمار 4 (75 درصد آب ژرف) و یک (100 درصد محیط کشت) بود. همچنین بیشترین و کمترین بیومس به‌ترتیب برای تیمار 5 (100 درصد آب ژرف) و 3 (50 درصد آب ژرف) بود. بیشترین و کمترین میزان کلروفیل a نیز به‌ترتیب برای تیمار 5 (100 درصد آب ژرف) در روز سوم و تیمار 3 (50 درصد آب ژرف) در روز آخر بود. بنابراین، طبق نتایج این مطالعه، پرورش ریزجلبک C. vulgaris در آب چاه ژرف امکان‌پذیر است. Introduction Microalgae can produce valuable compounds, such as pigments, minerals, amino acids and fatty acids, proteins, and vitamins that can be used in pharmaceutical, health, and food fields, with three economically important genera including Chlorella, Spirulina, and Dunaliella (Priyadarshani and Rath, 2012). Green algae include various forms: filamentous, membranous, unicellular, plate-like, or tubular. Chlorella is spherical in shape and have relatively thin walls. Reproduction in Chlorella is also very simple and occurs through asexual reproduction (Kerem et al., 2008). C. vulgaris can stimulate plant growth in agriculture and suppress the growth of pathogenic microorganisms (Allaguvatova et al., 2019). Chlorella is an important species of green algae that is fed to rotifers, various aquatic larvae and some phytophagous fish in fish farming ponds and aquatic ecosystems (Salavatian and Fallahi, 2005). Deep aquifer well water is a source of groundwater that is considered a strategic asset in any country. Deep water, which is located at a depth of 300 to 1200 meters, is not suitable for drinking due to high salinity and dissolved solids, but it is suitable for agricultural activities. These water resources are valuable in countries with arid and desert climates. The first deep water well in Iran was commissioned in 2018 in the Sistan region with the capacity to produce 1,500 m3 of water per day (Khosravanizadeh et al., 2021). This research was conducted considering the closeness of the salinity level of deep water in Well No. 1 of Sistan to the requirements of C. vulgaris algae, and can be an introduction to the possibility of further studies on various algae in these waters. Methodology The experiment was conducted in the Microalgae Research Laboratory of Zabol Research Institute. The microalgae stock C. vulgaris was obtained from the Fars Algae Biological Reserves Development Company. To achieve the appropriate concentration of microalgae for cultivation, the prepared stock was cultured in 500 ml Erlenmeyer flasks for one week at a salinity of 24.5 parts per thousand (distilled water and Lake Urmia salt) and 1.5 ml of Gaillard culture medium per liter. This experiment was conducted with 5 treatments (treatment 1: 100% culture medium. Treatment 2: 25% deep aquifer well water plus 75% culture medium. Treatment 3: 50% deep aquifer well water plus 50% culture medium. Treatment 4: 75% deep aquifer well water plus 25% culture medium. Treatment 5: 100% deep aquifer well water, and 3 repetitions during the duration of 10 days. It was done at a temperature of 27˚c and 3500 lux lighting and continuous aeration in 500 ml containers. pH was measured using a pH meter. To measure the density in different treatments, the number of cells was counted every other day using a Neobar slide and a light microscope (magnification ×40). Algae growth rate in different treatments including specific growth rate (SGR) (percentage per day) and: doubling time (DT) (per day) were calculated using the relevant formulas (Hibbered, 1981). Biomass dry weight was calculated using the method of Colusse et al. )2020(, and chlorophyll a content was calculated using the method of Lim et al. in 1991 and the corresponding formula. The collected data were statistically analyzed using SPSS version 22 software. The normality of the data and the homogeneity of variances were checked with Kolmogorov-Smirnov and Levene's tests. One-way ANOVA was used to determine the difference in means. Also, Duncan's test with a level of (p˂0.05) was used to compare means. Results An examination of the pH changes in the experimental treatments shows that the highest fluctuation of these changes occurred on the first day of the experiment, from pH 8.98 to 10.63 on the fifth day. The initial density in all treatments on the first day of the experimental period was 15×104 cells ml-1. Chlorella algae showed increasing growth in all treatments until day 5 of the experiment, with the highest density in the fifth treatment being 129.33×104 cells ml-1. However, no significant difference was observed between treatments (p > 0.05). Also, on the third day of the experiment, the highest specific growth rate (SGR) of C. vulgaris algae was related to treatment 1 (100% Gaillard culture medium) and the lowest was on the last day for treatment 4 (75% deep aquifer well water). In addition, the results of this study show that the highest doubling time (DT) is observed in treatment 4 (25% deep aquifer well water) on the last day and the lowest time for treatment 1 (100% Gaillard medium) on the third day. The results of measuring the concentration of chlorophyll a show that the highest and lowest levels of this pigment were observed on the third day of the experiment in treatment 5 (100% deep aquifer well water) and treatment 3 (50% deep aquifer well water), respectively. Also, the results related to the dry weight of this alga indicate that the highest average was recorded on the tenth day (treatment 5) and the lowest for treatment 3 on the third day of the experiment. Also, a significant difference was observed between the treatments only on the third day of the experiment (p˂0.05). <div aria-label="Page Break" class="cke_pagebreak" contenteditable="false" data-cke-display-name="pagebreak" data-cke-pagebreak="1" style="page-break-after:always" title="Page Break"></div>Discussion and conclusion Algae have the ability to utilize waste and can produce valuable materials such as pharmaceuticals, chemicals, and human and animal food through light energy and inexpensive natural materials such as carbon dioxide (De la noue and Pauw, 1988). Therefore, the necessity of cultivating this type of algae in saline water environments is felt, and considering the new water source in the Sistan region, the necessity of faster and cheaper growth in its mass production seems necessary. For this reason, Chlorella vulgaris is used in this study to investigate its growth process in the deep aquifer well water of the Sistan region and the Gaillard culture medium. Light, temperature, pH, water quality, aeration rate and the presence of nutrients are considered as factors affecting the production of microalgae (Ayala, 1998). In the present study, the pH fluctuation in Table 2 for treatments containing deep water was in the range of 10-9. pH is one of the most important parameters for algae growth because it can determine the availability of carbon dioxide and nutrients. A study by Habibi et al. in 2011 showed that the highest growth of Chlorella was recorded at pH 9.5, although it maintained its growth and survival at higher pH (12). The results of this study showed that the highest growth was in the pH range of 7 to 8, which could be explained by the difference in environmental conditions and the type of algae species. The results of this study showed that the highest density of C. vulgaris species was observed in treatment 5 (100% deep aquifer well water) on the fifth day with an average density of 129.33×104 cells ml-1. A study by Rahdari et al. (2023) investigating the ability to cultivate the microalgae Dunaliella tertiolecta in the deep aquifer well waters of Sistan also showed that the highest number of this microalga was 24 ×106 cells ml-1. It seems that factors such as the type of species and the conditions of the microalgae cultivation environment, such as the type of water, the salinity of the water, the culture medium, etc., are effective in the cell density of this alga in various studies. According to the results of this research, it seems that the microalga C. vulgaris has the ability to be cultivated in deep water, but further studies are needed to achieve the appropriate combination of this water (deep water) with municipal or distilled water to achieve the desired salinity. Conflict of Interest The authors declare that they have no conflict of interest. Acknowledgment This work was financially supported by a grant <a name="_Hlk203303377">(UOZ-8746) </a>from the Vice Chancellor for Research Affairs of University of Zabol. We would like to express our gratitude. Chlorella vulgaris , رشد, کلروفیل a, نرخ رشد ویژه, آب ژرف سیستان Chlorella vulgaris, Growth, Chlorophyll a, Specific growth rate, Deep ground water of Sistan 71 80 http://isfj.ir/browse.php?a_code=A-10-1345-8&slc_lang=fa&sid=1 Fatemeh Mir فاطمه میر fatemehmir0033@gmail.com 100319475328460040057 100319475328460040057 No University of Zabol گروه شیلات، دانشکده منابع طبیعی، دانشگاه زابل، زابل، ایران Javad Mirdar Harijani جواد میردار هریجانی javadmirdar@gmail.com 100319475328460040058 100319475328460040058 Yes University of Zabol گروه شیلات، دانشکده منابع طبیعی، دانشگاه زابل، زابل، ایران Ahmad Gharaei احمد قرایی agharaei551@gmail.com 100319475328460040059 100319475328460040059 No University of Zabol گروه شیلات، دانشکده منابع طبیعی، دانشگاه زابل، زابل، ایران Abdolali Rahdari عبدالعلی راهداری rahdari67@gmail.com 100319475328460040060 100319475328460040060 No Research Institute of Zabol گروه علوم آبزیان، پژوهشکده تالاب بین المللی هامون، پژوهشگاه زابل. زابل. ایران