Corallococcus soli sp. Nov., a Soil Myxobacterium Isolated from Subtropical Climate, Chalus County, Iran, and Its Potential to Produce Secondary Metabolites.

A novel myxobacterial strain ZKHCc1 1396T was isolated in 2017 from a soil sample collected along Chalus Road connecting Tehran and Mazandaran, Iran. It was a Gram-negative, rod-shaped bacterial strain that displayed the general features of Corallococcus, including gliding and fruiting body formation on agar and microbial lytic activity. Strain ZKHCc1 1396T was characterized as an aerobic, mesophilic, and chemoheterotrophic bacterium resistant to many antibiotics. The major cellular fatty acids were branched-chain iso-C17:0 2-OH, iso-C15:0, iso-C17:1, and iso-C17:0. The strain showed the highest 16S rRNA gene sequence similarity to Corallococcusterminator CA054AT (99.67%) and C. praedator CA031BT (99.17%), and formed a novel branch both in the 16S rRNA gene sequence and phylogenomic tree. The genome size was 9,437,609 bp, with a DNA G + C content of 69.8 mol%. The strain had an average nucleotide identity (ANI) value lower than the species cut-off (95%), and with the digital DNA-DNA hybridization (dDDH) below the 70% threshold compared to the closest type strains. Secondary metabolite and biosynthetic gene cluster analyses revealed the strain's potential to produce novel compounds. Based on polyphasic taxonomic characterization, we propose that strain ZKHCc1 1396T represents a novel species, Corallococcus soli sp. nov. (NCCB 100659T = CIP 111634T).

Combination and improvement of conventional DNA extraction methods in Actinobacteria to obtain high-quantity and high-quality DNA.

Background and Objectives: DNA extraction is an important step of any molecular experiment. DNA could not be easily extracted from members of actinomycetes by the usual methods of lysis. Due to the low efficiency of the conventional DNA extraction methods, development of an effective technique for DNA extraction of actinobacteria in emergency cases seems to be necessary. Since most of the DNA extraction techniques and commercial kits are not efficient enough to extract DNA from actinobacteria, this study was conducted to improve an efficient method obtained from conventional one to extract DNA from this group of bacteria. Materials and Methods: DNA extraction was performed using five methods (an improved method, Invisorb Spin Plant Mini Kit, EZ-10 Spin Column, Sarrbrucken method (HZI, Germany) and Kirby Bauer's method). To evaluate the quantity and quality of extracted genomic DNA, UV absorbance of all samples and efficiency of polymerase chain reaction (PCR) were evaluated. Results: Overall, the results revealed that the highest quantity (up to 4000 ng/µl) and good quality of DNA was obtained using introduced DNA extraction method. Conclusion: Results indicated that recently introduced improved method was more efficient for extraction of DNA from actinobacteria for DDH (DNA-DNA hybridization) test and for those require the high concentration of DNA.

Isolation and identification of the bacterium producing antitumor and antimicrobial compounds derived from Iranian swamp frog (Rana ridibunda) skin.

BACKGROUND AND OBJECTIVES: Cancer incidence and recurrence, antibiotic resistance, and overuse of antibiotics have become a global concern. The purpose of this study was to identify and isolate bacteria from the skin of the Rana ridibunda, Iranian swamp frog, which has produced antimicrobial compounds, and investigate its cytotoxic activity on the breast (MCF7) and glioblastoma (U87) cancer cell line. MATERIALS AND METHODS: An antibiotic-producing bacterium was isolated from the frog skin. The bacterium was identified based on 16S rDNA sequencing and biochemical and morphological characteristics. Antimicrobial activity of the culture supernatant was examined by disc diffusion and MIC methods. Cytoplasmic and cell wall extracts of bacteria were prepared by sonication. SDS-PAGE was then used to examine protein contents of them. The cancer cell lines were treated with cytoplasmic and cell wall extracts at different concentrations. The effects of cytotoxicity were assessed by MTT assay at 24 and 48 h intervals. Finally, the results were analyzed by SPSS. RESULTS: The isolated bacterium was identified as a new strain of Bacillus atrophaeus. MIC and disc diffusion methods showed that the Bacillus atrophaeus antimicrobial activity was broad spectrum. MTT assay showed IC50 values 30 µg/ml and 20 µg/ml for U87 and MCF7 cells after 24-48 h exposure, respectively. CONCLUSION: The cytoplasmic extracts of Bacillus atrophaeus has anticancer potential and can be used as an alternative or complementary candidate in the treatment of cancer. Further in vivo and in vitro mechanistic studies are suggested to confirm the biological activities.

Structurally diverse metabolites from the rare actinobacterium Saccharothrix xinjiangensis.

The bioassay-guided fractionation from cultures of the actinobacterium Saccharothrix xinjiangensis Act24Zk, collected from the Caspian Sea beach in Iran led to the isolation of three new compounds, caerulomycin M (1), saccharopyrone (2), and saccharonoic acid (3), together with the known compound, caerulomycin A (4). Their structures were elucidated from HR-ESIMS and 1D and 2D NMR data. Compound 2 displayed moderate cytotoxic activity against the human cervix carcinoma HeLa cells KB3.1 with an IC50 value of 5.4 µM.