فهرست مطالب mahsa naderi samani

Isolation and identification of unknown microorganisms native to our country and their preservation in the collections of genetic resources in order to exploit their biological capacity are of special importance and necessity. This study aimed to identify halophyte microalgae living in the back-barrier Lipar located on the shores of the Oman Sea in Sistan and Baluchestan Province. Water and phytoplankton sampling was carried out from the back-barrier in 2019-2020. Isolation and purification of the collected microalgae were performed by serial dilution and F2 medium culture in agar and liquid media, and finally, pure single colonies were obtained. Then, the initial identification of isolates was done through microscopic observations and comparison with morphologically valid classification keys. In the next step, 18S rRNA and 16S rRNA genes were used for further verification and identification by molecular method and sequencing. Analysis of morphological data and molecular sequencing showed that two purified isolates were green microalgae Dunaliella salina and green-blue microalgae Cyanothece sp., which was identified for the first time from the back-barrier. In terms of biological and commercial capacity, these two microalgae are suitable species for mass production and are widely used in industry. The purified strains have been donated to the National Bank of Iran Genetic Resources for future research or industrial-scale exploitation.

One of the most important challenges lies in the microalgae mass production is the high cost of harvesting process which is the separation of a low amount of biomass consisting of small individual cells from a large volume of culture medium. Therefore, finding an efficient and costeffective technique for harvesting microalgae is important issue. In the current study, pH-induced flocculation method was tested for microalgae Cyanothece sp. harvesting. The halophilic microalgae were cultured and grown in laboratory with hypersaline water in F/2 medium. After reaching the stationary phase, the impact of pH induction (from natural medium culture pH:8.2 to pH:11) on flocculation efficiency, chlorophyll a, chlorophyll b, total carotenoid, β-Carotene and phycocyanin component and the possibility of reuse flocculated medium of microalgae Cyanothece sp. were evaluated. The results indicated that the increasing the medium pH value by adding NaOH from pH natural at 8.2 to 9.4 increased flocculation efficiency significantly from 10 up to 90% (P<0.05), but after that remained stable up to pH: 11. Regarding the pigment content, the increase in pH value from natural pH: 8.2 to pH: 9.1 had a relatively a medium effect on pigment components, including chlorophyll a, chlorophyll b, total carotenoid, β-Carotene and phycocyanin amount of the harvested biomass of Cyanothece sp, but after that from pH: 9.4 to 11 the reduction was severe. The medium culture from pH: 8.5 to pH: 11 was reusable for new culture of microalgae. Thus, the flocculation induced by pH increase up to pH: 9.1 is a suitable method for harvesting microalgae Cyanothece sp. with no serious adverse effect on pigment component.

Probiotics have more functional effects on shrimp immunological parameters but there is less information on comparative effects of Commercial and Indigenous probiotics on post-larvae and larval stage of shrimp life. This 60 day study was conducted to determine the effect of probiotic bacterium commercial and allochthonous (Bacillus subtilis and Bacillus licheniformis) on some of immune parameters and serum enzymes in the whiteleg shrimp (Litopenaeus vannamei). Three experimental diets were supplemented with similar concentration of 1.5×106 Cfu/g by bacteria, commercial and allochthonous supplementation. Control  (without probiotic supplementation), D1 (commercial probiotic), D2 (commercial+allochthonous probiotic) and D3 (allochthonous probiotic) were used for the experiment. At the end of trial, to evaluate immune parameters, Shrimp hemolymph was collected by syringe into the ventral sinus of L. vannamei, transferred to a tube and allowed to anticoagulant. To investigate serum enzymes level, body shrimp were homogenized and extracts were analyzed biochemically. Total haemocyte count (THC), large granular cells (LGC), semi granular cells (SGC) and hyaline cells (HC) treated with commercial probiotics increased in comparison with control and significant difference was observed (P<0.05). Enzyme alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly decreased in the experimental groups compared with control (P<0.05). However, post-larvae enzyme alkaline phosphatase was not found to be significantly affected by probiotic supplementation (P>0.05). The probiotic Bacillus influenced the increase of the immune parameters haemolyph and decreased serum enzymes level and it is appropriate for supplementation in the diet of whiteleg shrimp post-larvae.

This study was conducted to evaluate the effect of commercial probiotic including bacillus spores (5 species) on the bioremediation of the effluent of cultivation system of common carp fingerlings (Cyprinus carpio). This experiment was conducted in two treatments: Probiotic treatment (T1), the blend of bacilli which were added to the waste water of tanks at a concentration of 1×108 CFU/liter and control treatment which no bacilli were added. At the starting of the experiment and after inoculating of bacteria into the waste water, the water quality parameters, such as Total Ammonia Nitrogen, NO2-N, NO3-N, EC, TDS and turbidity were measured at the intervals of 24, 48 and 72 h. The employment of these bacterial bioremediator in the waste water of rearing system of common carp resulted in significantly lower concentrations of TAN. Also, turbidity and total count of bacteria significantly decreased after 48h and NO3-N significantly decreased after 72h (P