جستجوی مقالات مرتبط با کلیدواژه « spring » در نشریات گروه « زیست شناسی »

Diatoms are the most diverse algae of the aquatic ecosystems and springs are of high value as the habit of high biodiversity and an important source of drinking for mankind. Therefore, study of the springs' algae flora is very important at the conservation view. In this research, the diatom biodiversity of the Tizab Spring and the spring-fed river was studied for the first time. Thirty species were identified of which one species (Achnanthidium gracillimum) is a new record for diatom flora of Iran. The data revealed that the flora is much similar to the Karaj River flora. This similarity can be due to the close geographical locations as both rivers are located in the Central Alborz region. The distribution pattern of the species were studied in Iran based on the present references on the Iranian aquatic ecosystems. This study presented that two-third of the species had a widespread distribution. The comparison of the flora with known European and American database showed that most species are the elements of the northern hemisphere. Diatom biodiversity studies in the Central Alborz region is in its first steps. Therefore, much research should be performed to reveal the diatom biodiversity and the potential new species in the region.

L-asparaginase has lots of medical and industrial applications. Ever since L-asparaginase anti-tumor activity was first demonstrated, its production using microbial systems has attracted considerable attention owing to their cost-effective and eco-friendly nature. The aim of this study is to obtain L-asparaginase producing bacteria and determining the enzyme activity. Samples were picked up from Jooshan hot springs located in the Sirch, Kerman. The L-asparaginase producing bacteria were screened on the agar medium supplied with L-asparagine and phenol red indicator dye (pH-7.0). L-asparaginase activity was detected on the basis of pink color around the colony. Enzyme production was also performed based on ammonia detection by Nessler method. Among 24 strains, there were 7 strains which could produce L-asparaginase.Sequencing of 16S rRNA showed that, the best isolates producing L-asparaginase belongs to the Pseudomonas genus. Enzyme activity after 24 and 48 h of incubation showed that Pseudomonas pseudoalcaligenes strain JHS-71was the best strain that produced L-Asparaginase about 240 (U/ml) after 48h of incubation. Results showed that, L-Asparaginase activity enhanced about 27% in the presence of Co. L-asparaginase JHS-71 retained more than 50% of its initial activity in the presence of Cu, Mn, Zn, Mg and Fe. Because of various applications of L-asparaginase in biotechnology, P. pseudoalcaligenes strain JHS-71 can be used as a suitable candidate in these fields.