University of Isfahan Journal of Microbial Biology 3060-7647 9 34 2020 06 21 Identifying Uricase-Producing Arthrobacter and Bordetella Bacterial Strains and Comparing the Enzyme Activity Identifying Uricase-Producing Arthrobacter and Bordetella Bacterial Strains and Comparing the Enzyme Activity 1 12 24967 10.22108/bjm.2020.119988.1235 FA Mojtaba Shaban Department of biology, faculty of sciences, Shahid Bahonar University of Kerman, Kerman, Iran Arastoo Badoei-dalfard Faculty of science, shahid bahonar university of kerman Journal Article 2019 11 11 Introduction: Uricase (urate oxidase) is a therapeutic enzyme that belongs to the class of oxidoreductases and catalyzes the oxidation of uric acid to allantoin, carbon dioxide, and hydrogen peroxide and also plays a vital role in the purine metabolic pathway. Nowadays, bacterial uricase enzyme has received special attention from researchers. Materials and methods: Poultry soils are great places for the growth of uricotelic bacteria due to having high sources of uric acid. Poultry soils were collected from Kerman city and bacterial strains were isolated. The decomposition of uric acid was performed by inoculating bacteria on a solid medium containing uric acid as the only source of carbon and nitrogen. The screening was performed by monitoring the appearance of clear zones around the colonies of bacteria indicating the decomposition of uric acid. Uricase activity was investigated by the Phosphotungstic acid method. The molecular identification of strains was performed using 16S rDNA gene sequence and drawing the phylogenetic tree. Results: In this study, two bacterial species capable of producing uricase enzyme were isolated from a poultry source and screened based on the size of the clear zone using a uric acid agar plate. Arthrobacter sp.KBUBand Bordetella sp.KMU3 strains were identified based on the 16S rDNA gene sequences. The production of uricase was performed during different incubation periods and the results showed that the maximum uricolytic activity of 25 and 15 U/mL was achieved by Arthrobacter sp.KBUBand Bordetella sp.KMU3, respectively. Discussion and conclusion: The capability of both these strains to produce uricase was confirmed using solid and liquid media. Arthrobacter sp.KBUB has shown a high ability to produce uricase, which can be used as a therapeutic enzyme and biosensor construction to measure uric acid. Introduction: Uricase (urate oxidase) is a therapeutic enzyme that belongs to the class of oxidoreductases and catalyzes the oxidation of uric acid to allantoin, carbon dioxide, and hydrogen peroxide and also plays a vital role in the purine metabolic pathway. Nowadays, bacterial uricase enzyme has received special attention from researchers. Materials and methods: Poultry soils are great places for the growth of uricotelic bacteria due to having high sources of uric acid. Poultry soils were collected from Kerman city and bacterial strains were isolated. The decomposition of uric acid was performed by inoculating bacteria on a solid medium containing uric acid as the only source of carbon and nitrogen. The screening was performed by monitoring the appearance of clear zones around the colonies of bacteria indicating the decomposition of uric acid. Uricase activity was investigated by the Phosphotungstic acid method. The molecular identification of strains was performed using 16S rDNA gene sequence and drawing the phylogenetic tree. Results: In this study, two bacterial species capable of producing uricase enzyme were isolated from a poultry source and screened based on the size of the clear zone using a uric acid agar plate. Arthrobacter sp.KBUBand Bordetella sp.KMU3 strains were identified based on the 16S rDNA gene sequences. The production of uricase was performed during different incubation periods and the results showed that the maximum uricolytic activity of 25 and 15 U/mL was achieved by Arthrobacter sp.KBUBand Bordetella sp.KMU3, respectively. Discussion and conclusion: The capability of both these strains to produce uricase was confirmed using solid and liquid media. Arthrobacter sp.KBUB has shown a high ability to produce uricase, which can be used as a therapeutic enzyme and biosensor construction to measure uric acid.

https://bjm.ui.ac.ir/article_24967_72b451532a72d6a5cfbb74e5222f6ecb.pdf

University of Isfahan Journal of Microbial Biology 3060-7647 9 34 2020 06 21 A Phenotypic and Genotypic Study of Colistin arn Resistance Regulator Gene Classes in Acinetobacter Baumannii isolated from Clinical Cases using Multiplex PCR A Phenotypic and Genotypic Study of Colistin arn Resistance Regulator Gene Classes in Acinetobacter Baumannii isolated from Clinical Cases using Multiplex PCR 13 21 24757 10.22108/bjm.2020.120342.1248 FA Farnoosh Karimi Department of Microbiology, Faculty of Basic Sciences, Saveh Branch, Islamic Azad University, Saveh, Iran Kumarss Amini Department of Microbiology, School of Basic Sciences, Saveh Branch, Islamic Azad University, Saveh, Iran. 0000-0002-6419-3417 Gholamreza Javadi Department of Microbiology, Faculty of Basic Sciences, Saveh Branch, Islamic Azad University, Saveh, Iran Journal Article 2019 12 25 Introduction: Colistin is considered as the last line of treatment in nosocomial infections caused by Acinetobacter baumannii. Nowadays, with the elucidation of resistance transition mechanisms through arn genes, a new drug resistance pattern has been observed in Acinetobacter baumannii isolates. The aim of this study was to investigate the phenotypic and genotypic roles of the genes for regulating resistance to Colistin (arn) in strains isolated from clinical cases. Materials and methods: To conduct this descriptive study, after obtaining the written consent, 400 clinical samples were collected from patients admitted to Hazrat-e-Rasoul Hospital in Tehran. After the identification of the isolates using biochemical methods and 16srDNA analysis, the antibiotic resistance pattern of the isolates was determined by disk diffusion and molecular methods (to detect arnT, arnB genes). Results: Sixty Acinetobacter baumannii strains were isolated from 400 samples. The results of antibiotic resistance analysis showed that, in most cases, more than 38% of blood samples had Acinetobacter species. Also, no Acinetobacter was found in any of the spinal cord specimens, which showed the lowest infection rate (p <0.05). There was also a significant difference between the antibiotic susceptibility of Acinetobacter baumannii isolates to Colistin and other antibiotics (p <0.05). In addition, Colistin resistant strains had arnB and arnT genes, which were considered statistically significant (p <0.05) compared to other strains. Discussion and conclusion: Since Colistin is used as the last line of treatment, increased resistance to it can lead to increased mortality and hospital costs. Therefore, the application of new therapeutic regimens and greater sensitivity to the timely diagnosis and control of nosocomial infections seems necessary. Introduction: Colistin is considered as the last line of treatment in nosocomial infections caused by Acinetobacter baumannii. Nowadays, with the elucidation of resistance transition mechanisms through arn genes, a new drug resistance pattern has been observed in Acinetobacter baumannii isolates. The aim of this study was to investigate the phenotypic and genotypic roles of the genes for regulating resistance to Colistin (arn) in strains isolated from clinical cases. Materials and methods: To conduct this descriptive study, after obtaining the written consent, 400 clinical samples were collected from patients admitted to Hazrat-e-Rasoul Hospital in Tehran. After the identification of the isolates using biochemical methods and 16srDNA analysis, the antibiotic resistance pattern of the isolates was determined by disk diffusion and molecular methods (to detect arnT, arnB genes). Results: Sixty Acinetobacter baumannii strains were isolated from 400 samples. The results of antibiotic resistance analysis showed that, in most cases, more than 38% of blood samples had Acinetobacter species. Also, no Acinetobacter was found in any of the spinal cord specimens, which showed the lowest infection rate (p <0.05). There was also a significant difference between the antibiotic susceptibility of Acinetobacter baumannii isolates to Colistin and other antibiotics (p <0.05). In addition, Colistin resistant strains had arnB and arnT genes, which were considered statistically significant (p <0.05) compared to other strains. Discussion and conclusion: Since Colistin is used as the last line of treatment, increased resistance to it can lead to increased mortality and hospital costs. Therefore, the application of new therapeutic regimens and greater sensitivity to the timely diagnosis and control of nosocomial infections seems necessary.

https://bjm.ui.ac.ir/article_24757_1cdc99bc26d37dd9d73e72b4b532f726.pdf

University of Isfahan Journal of Microbial Biology 3060-7647 9 34 2020 06 21 Optimizing the Cultivation Conditions of Fischerella sp. SH.A Cyanobacterium for Maximizing Polysaccharide Production with Antibacterial Activity Optimizing the Cultivation Conditions of Fischerella sp. SH.A Cyanobacterium for Maximizing Polysaccharide Production with Antibacterial Activity 23 53 25036 10.22108/bjm.2020.120846.1261 FA Shadab Abbaspour Department of Biology, Faculty of science, Central Tehran Branch, Islamic Azad University, Tehran, Iran &lrm; Bahareh Nowruzi Department of Biology, Faculty of science, Science and Research Branch, Islamic Azad University, Tehran&lrm; 0000-0001-6656-777X S. M. M Hamdi Department of Biology, Faculty of science, Central Tehran Branch, Islamic Azad University, Tehran, Iran Journal Article 2019 12 31 Introduction: Among the photosynthetic microorganisms, cyanobacteria belonging to the genus Fischerella appear particularly promising for new polysaccharides producing strains. Extracellular polysaccharides (EPS) serve as a boundary to the immediate environment and play a protective role against antimicrobial agents. That iswhy cyanobacteria are so popular in the industry today as thickeners or floating agents, heavy metal absorbers, or in the case of sulfate polysaccharides as bioactive substances. This is an advantage over other polysaccharides extracted from plants or other macroalgae. There are many factors affecting cell growth and metabolite accumulation in cell cultures. However, there is insufficient knowledge about the factors affecting maximal EPS biosynthesis and antibacterial activity. In this regard, in this paper, the effect of some physical, environmental, and nutritional factors on the simultaneous production of exopolysaccharide by Fischerella sp. SH.A was investigated in order to select the best cultivation conditions for the industrial application of exopolysaccharides. Materials and methods: In this study, the cyanobacterium isolated from the fresh water of Golestan province was undertaken with the aim of investigating the key factors regulating EPS biosynthesis and antibacterial activity. After the morphological and molecular identification, the possible correlations between the type of stress and the amount of polysaccharides production were also investigated. Results: The obtained results indicated that EPS production and antibacterial activity were highly dependent on the culture conditions and light intensity. Furthermore, the production of exopolysaccharides in non-diastrophic conditions was highly correlated with the concentration of nitrate up to 500 mM and the illumination of 50 or 150 microeinsteins per second per square meter. Discussion and conclusion: Since cyanobacterial extracellular polysaccharides are interesting from the biotechnological point of view, considering some other parameters are of crucial importance for the maximization of EPS production in this genus. Introduction: Among the photosynthetic microorganisms, cyanobacteria belonging to the genus Fischerella appear particularly promising for new polysaccharides producing strains. Extracellular polysaccharides (EPS) serve as a boundary to the immediate environment and play a protective role against antimicrobial agents. That iswhy cyanobacteria are so popular in the industry today as thickeners or floating agents, heavy metal absorbers, or in the case of sulfate polysaccharides as bioactive substances. This is an advantage over other polysaccharides extracted from plants or other macroalgae. There are many factors affecting cell growth and metabolite accumulation in cell cultures. However, there is insufficient knowledge about the factors affecting maximal EPS biosynthesis and antibacterial activity. In this regard, in this paper, the effect of some physical, environmental, and nutritional factors on the simultaneous production of exopolysaccharide by Fischerella sp. SH.A was investigated in order to select the best cultivation conditions for the industrial application of exopolysaccharides. Materials and methods: In this study, the cyanobacterium isolated from the fresh water of Golestan province was undertaken with the aim of investigating the key factors regulating EPS biosynthesis and antibacterial activity. After the morphological and molecular identification, the possible correlations between the type of stress and the amount of polysaccharides production were also investigated. Results: The obtained results indicated that EPS production and antibacterial activity were highly dependent on the culture conditions and light intensity. Furthermore, the production of exopolysaccharides in non-diastrophic conditions was highly correlated with the concentration of nitrate up to 500 mM and the illumination of 50 or 150 microeinsteins per second per square meter. Discussion and conclusion: Since cyanobacterial extracellular polysaccharides are interesting from the biotechnological point of view, considering some other parameters are of crucial importance for the maximization of EPS production in this genus.

https://bjm.ui.ac.ir/article_25036_553f3857aa2a4351cd33c6a171f45704.pdf

University of Isfahan Journal of Microbial Biology 3060-7647 9 34 2020 06 21 A Phylogenetic Analysis of HC-Pro Protein in Iranian Isolates of Bean Yellow Mosaic Virus A Phylogenetic Analysis of HC-Pro Protein in Iranian Isolates of Bean Yellow Mosaic Virus 55 70 25011 10.22108/bjm.2020.120883.1262 FA Ali Baradar Department of Plant Protection, Faculty of Agriculture, Vali-e-University of Rafsanjan, Iran Ahmad Hosseini Department of Plant Protection, Faculty of Agriculture, Vali-e-University of Rafsanjan, Iran Samin Hosseini Department of Plant Protection, Faculty of Agriculture, Vali-e-University of Rafsanjan, Iran Somayeh Abdani Babaki Department of Plant Protection, Faculty of Agriculture, Vali-e-University of Rafsanjan, Iran Journal Article 2020 01 12 مقدمه: ویروس موزاییک زرد لوبیا (Bean yellow mosaic virus)به جنس Potyvirus و خانوادۀ Potyviridaeتعلقدارد و دارای پراکندگی جهانی گسترده و دامنۀ میزبانی وسیع است. در پژوهش حاضر، روابط فیلوژنتیکی 8 جدایۀ این ویروس که در سال‌های زراعی 96 و 97 از مناطق جغرافیایی مختلف ایران (آذربایجان شرقی، اردبیل، قزوین، زنجان، همدان، خوزستان، فارس و کرمان) از روی باقلا جدا شده بودند، در مقایسه با سایر جدایه‌های موجود در بانک ژن بررسی شدند. مواد و روش‏‏ها: برگ‌های گیاهان دارای نشانه‌های ویروسی از مزارع باقلای نواحی مختلف ایران نمونه‏برداری و به آزمایشگاه منتقل شدند. به‌منظور تشخیص نمونه‌های آلوده به ویروس موزاییک زرد لوبیا، ابتدا از آزمون داس الیزا و آنتی‌بادی اختصاصی ویروس استفاده شد؛ سپس RNA کل نمونه‌های آلوده استخراج و ناحیۀ HC-Proجدایه‌های انتخابی تکثیر و توالی‌یابی شد. ارزیابی توالی، بررسی روابط فیلوژنتیکی، بررسی ساختار پروتئینی و همچنین شناسایی وقوع نوترکیبی در ناحیۀ HC جدایه‌های BYMV انتخابی با نرم‌افزارهای مختلف انجام شد. نتایج: در درخت فیلوژنتیکی رسم‌شده، جدایه‌های ایرانی در دو گروه مونوفیلتیک مجزا قرار گرفتند؛ به‌طوری‌که پنج جدایۀ آذربایجان‌ شرقی، قزوین، زنجان، فارس و کرمان در کنار دو جدایه از استرالیا و ژاپن که همگی از روی باقلا جدا شده بودند، در یک گروه جای گرفتند و جدایه‌ها‌‌ی اردبیل، همدان و خوزستان به همراه دو جدایۀ دیگر ایرانی موجود در بانک ژن، دو جدایه از هند و دو جدایه از ژاپن در گروه دیگر قرار گرفتند. بر اساس نتایج آزمون نوترکیبی، هیچ‌کدام از جدایه‌های ایرانی جمع‌آوری‌شده در پژوهش حاضر، جدایۀ نوترکیب تشخیص داده نشدند. بحث و نتیجه‏گیری: درک تغییرات ژنتیکی و نوترکیبی جمعیت ویروسی پیش‌نیاز مهمی برای تشخیص کارآمد، مدیریت مؤثر و کنترل بیماری در درازمدت است. قطعاً نتایج در توسعۀ راهکار‌هایی کاربرد دارند که به مقاومت در برابر BYMV منتج می‌شوند و چنانچه این بیماری در آینده همه‌گیر شود، می‌توانند در راستای اتخاذ راهبردهای مدیریتی اثربخش باشند. مقدمه: ویروس موزاییک زرد لوبیا (Bean yellow mosaic virus)به جنس Potyvirus و خانوادۀ Potyviridaeتعلقدارد و دارای پراکندگی جهانی گسترده و دامنۀ میزبانی وسیع است. در پژوهش حاضر، روابط فیلوژنتیکی 8 جدایۀ این ویروس که در سال‌های زراعی 96 و 97 از مناطق جغرافیایی مختلف ایران (آذربایجان شرقی، اردبیل، قزوین، زنجان، همدان، خوزستان، فارس و کرمان) از روی باقلا جدا شده بودند، در مقایسه با سایر جدایه‌های موجود در بانک ژن بررسی شدند. مواد و روش‏‏ها: برگ‌های گیاهان دارای نشانه‌های ویروسی از مزارع باقلای نواحی مختلف ایران نمونه‏برداری و به آزمایشگاه منتقل شدند. به‌منظور تشخیص نمونه‌های آلوده به ویروس موزاییک زرد لوبیا، ابتدا از آزمون داس الیزا و آنتی‌بادی اختصاصی ویروس استفاده شد؛ سپس RNA کل نمونه‌های آلوده استخراج و ناحیۀ HC-Proجدایه‌های انتخابی تکثیر و توالی‌یابی شد. ارزیابی توالی، بررسی روابط فیلوژنتیکی، بررسی ساختار پروتئینی و همچنین شناسایی وقوع نوترکیبی در ناحیۀ HC جدایه‌های BYMV انتخابی با نرم‌افزارهای مختلف انجام شد. نتایج: در درخت فیلوژنتیکی رسم‌شده، جدایه‌های ایرانی در دو گروه مونوفیلتیک مجزا قرار گرفتند؛ به‌طوری‌که پنج جدایۀ آذربایجان‌ شرقی، قزوین، زنجان، فارس و کرمان در کنار دو جدایه از استرالیا و ژاپن که همگی از روی باقلا جدا شده بودند، در یک گروه جای گرفتند و جدایه‌ها‌‌ی اردبیل، همدان و خوزستان به همراه دو جدایۀ دیگر ایرانی موجود در بانک ژن، دو جدایه از هند و دو جدایه از ژاپن در گروه دیگر قرار گرفتند. بر اساس نتایج آزمون نوترکیبی، هیچ‌کدام از جدایه‌های ایرانی جمع‌آوری‌شده در پژوهش حاضر، جدایۀ نوترکیب تشخیص داده نشدند. بحث و نتیجه‏گیری: درک تغییرات ژنتیکی و نوترکیبی جمعیت ویروسی پیش‌نیاز مهمی برای تشخیص کارآمد، مدیریت مؤثر و کنترل بیماری در درازمدت است. قطعاً نتایج در توسعۀ راهکار‌هایی کاربرد دارند که به مقاومت در برابر BYMV منتج می‌شوند و چنانچه این بیماری در آینده همه‌گیر شود، می‌توانند در راستای اتخاذ راهبردهای مدیریتی اثربخش باشند.

https://bjm.ui.ac.ir/article_25011_534ce2e4c4d1b2d46ee4ac45acd1e6c4.pdf

University of Isfahan Journal of Microbial Biology 3060-7647 9 34 2020 06 21 Optimization of L-asparaginase Production from a Lactobacillus sp. isolated from Traditional Dairy Products Optimization of L-asparaginase Production from a Lactobacillus sp. isolated from Traditional Dairy Products 71 86 24990 10.22108/bjm.2020.121143.1283 FA Behnush Dinarvand Department of Biology, Faculty of Basic Sciences, University of Maragheh, Maragheh, Iran Parisa Fathi Rezaei Department of Biology, Faculty of Science, University of Maragheh, Maragheh, Iran. Neda Akbari Department of Microbiology, Faculty of Science, Islamic Azad University, Arak Branch, Arak, Iran Journal Article 2020 03 15 Introduction: Asparaginase catalyzes the deamination of asparagine into aspartate and ammonia. Currently, it is used as an important chemotherapeutic agent for the treatment of different cancers such as acute lymphoblastic leukemia, malignant diseases of the lymphoid system, and Non-Hodgkin Lymphoma (NHL). Asparaginase is a useful enzyme for the food industry due to its potential to prevent acrylamide formation and to maintain the quality of the food. Probiotic products contain useful bacteria that have beneficial effects on health. The most important biological properties of probiotics include the elimination of mutagenic and carcinogenic agents. There are many microorganisms that could potentially function as the probiotic, the most common of which are Lactobacillus and Bifidobacterium species. The aim of this study was to optimize the production of L-asparaginase from isolated Lactobacillus sp. from the traditional whey of Maragheh. Materials and methods: The isolate was investigated through microbial and biochemical tests including gram staining, catalase and oxidase activity, fermentation of carbohydrates, and acid and bile salts resistance. Asparaginase production was evaluated by qualitative and quantitative methods, rapid plate assay, and Imada method, respectively. Asparaginase production was optimized by the Response Surface Method (RSM). Results: According to the RSM results, the highest activity of asparaginase was 131 U/mg, which was 11% more than the non-optimized condition. The optimized parameters composed of asparagine (1.75 %), glucose (2 %), and yeast extract (1.25 %). Furthermore, the total protein content and biomass of the optimized medium were 0.893 mg/ml and 0.345 g, respectively. Discussion and conclusion: This isolated lactobacilli strain may be considered as a significant source for the production of the enzyme with the pharmacological value of asparaginase. Introduction: Asparaginase catalyzes the deamination of asparagine into aspartate and ammonia. Currently, it is used as an important chemotherapeutic agent for the treatment of different cancers such as acute lymphoblastic leukemia, malignant diseases of the lymphoid system, and Non-Hodgkin Lymphoma (NHL). Asparaginase is a useful enzyme for the food industry due to its potential to prevent acrylamide formation and to maintain the quality of the food. Probiotic products contain useful bacteria that have beneficial effects on health. The most important biological properties of probiotics include the elimination of mutagenic and carcinogenic agents. There are many microorganisms that could potentially function as the probiotic, the most common of which are Lactobacillus and Bifidobacterium species. The aim of this study was to optimize the production of L-asparaginase from isolated Lactobacillus sp. from the traditional whey of Maragheh. Materials and methods: The isolate was investigated through microbial and biochemical tests including gram staining, catalase and oxidase activity, fermentation of carbohydrates, and acid and bile salts resistance. Asparaginase production was evaluated by qualitative and quantitative methods, rapid plate assay, and Imada method, respectively. Asparaginase production was optimized by the Response Surface Method (RSM). Results: According to the RSM results, the highest activity of asparaginase was 131 U/mg, which was 11% more than the non-optimized condition. The optimized parameters composed of asparagine (1.75 %), glucose (2 %), and yeast extract (1.25 %). Furthermore, the total protein content and biomass of the optimized medium were 0.893 mg/ml and 0.345 g, respectively. Discussion and conclusion: This isolated lactobacilli strain may be considered as a significant source for the production of the enzyme with the pharmacological value of asparaginase.

https://bjm.ui.ac.ir/article_24990_c2e6c975f166d09058693ea085270f02.pdf

University of Isfahan Journal of Microbial Biology 3060-7647 9 34 2020 06 21 Investigating the Effect of Hydrogen Peroxide on Biomass and Morphophysiological Indices of Microalga Dunaliella Salina Pretreated by Four Phytohormones: Auxin, Gibberellin, Cytokinin, and Salicylic Acid Investigating the Effect of Hydrogen Peroxide on Biomass and Morphophysiological Indices of Microalga Dunaliella Salina Pretreated by Four Phytohormones: Auxin, Gibberellin, Cytokinin, and Salicylic Acid 87 104 24978 10.22108/bjm.2020.122183.1285 FA Azin Ghafarizadeh Department of Biology Plant Physiology, Faculty of Science, Lorestan University, Khoramabad, Iran Maryam Madadkar Haghjou Department of Biology Plant Physiology, Faculty of Science, Lorestan University, Khoramabad, Iran Journal Article 2020 03 18 Introduction: Under unfavorable conditions, Reactive Oxygen Species (ROS) are produced inside living cells. Oxidant molecules such as H2O2 could be used to study the microorganism responses to oxidative stress. The treatment of algae with phytohormones can improve their physiological indices. In this study, the effect of H2O2 on unicellular green alga Dunaliella salina, pretreated by IAA (auxin), GA3 (gibberellin), Cyt (cytokinin), and SA (salicylic acid) was studied at three concentrations. Materials and methods: A 23-days algal culture was treated by phytohormones (in three repetitions) at three concentrations, and two days later (day 25), H2O2 (0.1 mM) treatment was performed. Two controls were considered without hormone and without H2O2, respectively. Evaluation of the growth and number of cells, fresh and dry weights, cell size (length, width, and volume), Chl a and b, beta-carotene, soluble carbohydrate, and protein were performed in days 25 and 27. Results: Hormones in most cases significantly improved the Indices (compared to the hormone-free control sample) (p <0.05). H2O2 treatment, two days after pre-treatment with hormones, caused the improvement of indices in most cases, except for protein and beta carotene. In contrast to the protein, the amount of carbohydrate was not sensitive to H2O2. The best results were obtained with IAA at medium concentration, GA3 at high concentration, Cyt and SA at low concentration. Discussion and conclusion: H2O2 positively influenced the effects of the four phytohormones on algae cells, especially in relation to increased algal biomass and cell division. The positive effect of H2O2 treatment on both pretreated with or without hormones was probably due to its concentration which was lower than the toxicity level. Therefore, algal cells have benefited more from the useful and signaling effects of this molecule. Introduction: Under unfavorable conditions, Reactive Oxygen Species (ROS) are produced inside living cells. Oxidant molecules such as H2O2 could be used to study the microorganism responses to oxidative stress. The treatment of algae with phytohormones can improve their physiological indices. In this study, the effect of H2O2 on unicellular green alga Dunaliella salina, pretreated by IAA (auxin), GA3 (gibberellin), Cyt (cytokinin), and SA (salicylic acid) was studied at three concentrations. Materials and methods: A 23-days algal culture was treated by phytohormones (in three repetitions) at three concentrations, and two days later (day 25), H2O2 (0.1 mM) treatment was performed. Two controls were considered without hormone and without H2O2, respectively. Evaluation of the growth and number of cells, fresh and dry weights, cell size (length, width, and volume), Chl a and b, beta-carotene, soluble carbohydrate, and protein were performed in days 25 and 27. Results: Hormones in most cases significantly improved the Indices (compared to the hormone-free control sample) (p <0.05). H2O2 treatment, two days after pre-treatment with hormones, caused the improvement of indices in most cases, except for protein and beta carotene. In contrast to the protein, the amount of carbohydrate was not sensitive to H2O2. The best results were obtained with IAA at medium concentration, GA3 at high concentration, Cyt and SA at low concentration. Discussion and conclusion: H2O2 positively influenced the effects of the four phytohormones on algae cells, especially in relation to increased algal biomass and cell division. The positive effect of H2O2 treatment on both pretreated with or without hormones was probably due to its concentration which was lower than the toxicity level. Therefore, algal cells have benefited more from the useful and signaling effects of this molecule.

https://bjm.ui.ac.ir/article_24978_6567fb796a82dd7a663928dec3a8d510.pdf