Streptomyces are capable of producing secondary metabolites including antibiotics and the main environment of these microorganisms is soil. The purpose of this study was to isolate and evaluate Streptomyces producing ANTIBACTERIAL compounds from different east parts of Gilan province and optimizing ANTIBACTERIAL compounds produced by them. After isolation and purification of Streptomyces, its ANTIBACTERIAL activity against pathogenic microorganisms including Micrococcus luteus PTCC 1408, Bacillus cereus PTCC 1154, Staphylococcus aureus PTCC 1189, Pseudomonas aeruginosa PTCC 1310, Salmonella typhi PTCC 1609 and Proteus mirabilis PTCC 1776 was investigated. Streptomyces was identified based on morpholigaical, biochemical, physiological, 16SrRNA gene sequencing and phylogenetic analysis. Optimization of various factors in the content of production of ANTIBACTERIAL compounds was investigated. In this study, 16SrRNA gene sequencing revealed that the isolate belonged to Streptomyces genus and with the highest similarity (95. 70%) to Streptomyces malachitospinus indicating significant differences at species level and it can be introduced as a new species. This isolate showed significant activity against pathogenic microorganisms. The optimum culture medium, pH, temperature, carbon and nitrogen sources and incubation time for the maximum ANTIBACTERIAL compounds production were ISP2, 7, 28° C, glycerol, yeast extract and 7 days, respectively. The results show that the soils of the eastern regions of Gilan province are a rich source of antimicrobial compounds, which due to the resistance of the pathogenic microorganisms to antimicrobial drugs, is essential for the production of antimicrobial compounds from natural origin.

Background: Nowadays the use of herbs as an alternative to the chemical drug is considered by researchers. Aloe vera belongs to the Asphodelaceae family, a medicinal plant that has been used since ancient times for different pharmaceutical products. This study aimed to evaluate the ANTIBACTERIAL properties of Aloe vera grown in Khouzestan, southwest of Iran. Materials and Methods: For this purpose, ethanol extract was prepared from aerial parts of Aloe vera and its activity was tested against some gram-positive (Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus) and gram-negative (Pseudomonass aeruginosa, Salmonella Typhi, Proteus mirabilis) bacterial species through standard Kirby-Bauer disc diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration were also investigated. Results: The Aloe vera extract showed ANTIBACTERIAL activity against the majority of bacteria. The highest activity (about 25mm inhibition zone) happened against P. aeruginosa but it did not show any inhibitory activity against S. aureus and P. mirabilis. The MIC was found as 10 mg/ml while MBC ≥ 80. Conclusion: Based on the results of this study it can be suggested that Aloe vera contains active ANTIBACTERIAL substances that can be used efficiently for bacterial pathogen control and it should be considered as a potent antimicrobial source for finding new antibiotics, especially against resistant species.

Background: Medicinal plants have now attracted more attention due to their ANTIBACTERIAL activity and also increasing antibiotic resistance among bacteria. Native plants of each region are potential resources for this purpose.Objectives: The aim of the present study was to detect the ANTIBACTERIAL effect of Eucalyptus microtheca (Myrtaceae family) which is currently used as an ANTIBACTERIAL fumigation medicine.Materials and Methods: Using standard disk diffusion method, the ANTIBACTERIAL activity, MIC, and MBC indexes of alcoholic extracts from this plant were tested on some pathogenic bacteria. The structural changes following the exposure to these extracts were also investigated in test bacteria.Results: Significant ANTIBACTERIAL activity was found against gram-positive and gram-negative bacteria, which among them, Escherichia. coli andPseudomonas. aeruginosa showed the most sensitivity and Staphylococcus. aureus the least. The value of MIC and MBC for both extracts was 8 mg/mL forE. coli, while they were 8 mg/mL and 16 mg/mL for Bacillus cereus, respectively. Both MIC and MBC values of methanolic and ethanolic extracts againstP. aeruginosa were 8 and 16 mg/mL respectively. SEM revealed structural changes in the affected bacteria that suggest the cell wall was the main target site of active constituents.Conclusions: It can be concluded that this plant has potential application in infection control, especially against E. coli and P. aeruginosa and regarding their recent reported epidemic, this plant can be a good choice for antibiotic discovery.