Search

Introduction: Microbial biofilms have attracted interest in recent years because they have become the most important cause of nosocomial infections. This study was aimed to examine the antibacterial activities of Peganum harmala extracts on the development of microbial biofilms and planktonic form of six pathogenic bacteria which include Staphylococcus aureus, Bacillus cereus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Materials and methods: Antimicrobial activities of the crude extracts against the planktonic form of bacteria were evaluated by using disc diffusion method, minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values were determined by a macrobroth dilution technique. Anti- biofilm effects of the extracts were assessed by microtiter plate method. Results: According to the results, P. harmala extracts could inhibit test bacteria in planktonic form. To inhibit biofilm formation, biofilm metabolic activity and eradication of established biofilms, efficiency of the extracts depended on concentration. The highest inhibitory effects of P. harmala extracts were observed on biofilm formation of S. aureus (90.28%) also, the greatest demolish were observed on S. pneumonia biofilm (77.76%). These extracts cause dramatically decrease the metabolic activity of bacteria in biofilm structures, in this case the decrement of B. cereus were highest (69.98%) compared to other tested bacteria. Discussion and conclusion: Therefore, it can be suggested that P.harmala extracts applied as antimicrobial agents against testing bacteria particularly in biofilm forms. [ABSTRACT FROM AUTHOR]

Phenol is one of the major aromatic pollutants among variety of toxic compounds. Phenol is a man-made as well as a naturally occurring aromatic compound and an important intermediate in the biodegradation of natural and industrial aromatic compounds. To clean up the aromatic contaminated sites a bioremediation method is considered as an economical and safe approach for the environment. In this study, 10 phenol-degrading bacterial strains were isolated from three sites at Midok copper mine in Shahrbabak. These sites include: Magnetit site (WG), Hematit site (WH) and Near Hematit site (NH). Total heterotrophic and phenol degrading bacteria were quantified with most probable number (MPN) and colony forming unit (CFU) methods. The results of this study show that the (WG) site of the mine have the highest phenol degrading bacteria. Totally 10 phenol degrading bacteria were isolated from three sites in Midok copper mine. Then, five bacterial strains were selected according to high growth rate and phenol degradation. Finally two strains named isolates P62 and 69P were selected for analysis of 16S rRNA sequences. Strain P62 belongs to Pseudomonas putidaAHBP62 and strain P69 is related to Arthrobacter scleromaeAHB69P that has capability degradation of 600 (ppm) phenols in 7 days. By using these degradative bacteria in contaminated mine sites the environmental pollution can be managed. [ABSTRACT FROM AUTHOR]

Introduction: Biofilms are communities of microorganisms embedded in a self-produced extracellular polymeric matrix. Bacterial cells are protected from antimicrobial agents in biofilm structure. Biofilms formation cause many problems in industry, medicine and microbial drug resistance; thus it is essential to find new techniques for removing and inhibiting biofilms. This study aimed to examine the antimicrobial effect of Tamarix hispida alcoholic extracts against six pathogenic bacteria in planktonic and biofim forms. Materials and methods: Antimicrobial activities of the plant extracts against the planktonic form of bacteria were evaluated by using the disc diffusion method. MIC and MBC values were determined by a macrobroth dilution technique. Anti-biofilm effects were assessed by microtiter plate method. Results: The results of this study confirmed high ability of T. hispida extracts against the biofilm of tested bacteria and their free-living forms. Methanolic extracts better inhibited bacterial growth and biofilm formation than ethanolic extracts. Anti-biofilm effects of plant extracts were depended on the solvent and extract concentration. The maximum inhibitory effects of T. hispida extracts on biofilm formation, demolish of biofilm structure and inhibition of metabolic activity of bacteria in the biofilm were observed for S. aureus (87/35 %), S. pneumonia (74/49 %) and B. ceruse (88/34 %) respectively. Discussion and conclusion: In this study the capacity of herbal extracts to encountering whit biofilm was demonstrated and it was confirmed that these extracts have interesting potentiality to become active agents of new drugs. [ABSTRACT FROM AUTHOR]

Variations on hydrophobicity were monitored in two marine obligate hydrocarbonoclastic bacteria: Alcanivorax borkumensis SK2T and Thalassolituus oleivoras MIL-1T. These strains were inoculated, separately in ONR7a mineral medium with different concentration of sodium acetate. During 10 days measurements of cellular abundance and cellular hydrophobicity (capacity to adhere at polystyrene) were carried out. Data obtained revealed that the natures of carbon source and growth phase are important factors in the regulation of adhesion of bacteria to the surfaces. Moreover Alcanivorax showed a major capability to colonize polystyrene respect on Thalassolituus in the experimented conditions. The understanding of capacity to adhesion of these bacteria for utilization of hydrophobic compounds is fundamental for their potential use in the mitigation of oil spills phenomenon. [ABSTRACT FROM AUTHOR]

Bacteria-Plant systems for bioremediation of oil polluted sites are one of the most effective approaches of biotechnology in the recent years. It is well known that oil pollution induces oxidative stress in plants. In this research, the effects of crude oil pollution on Zea mays and bioremediation by synergism between plant and crude oil degrading bacteria, four different treatments were designed. Some physiological and microbial factors were assayed for determining the effects of oil pollution. The results showed that 1% crude oil in soil shoot, dry weight was reduced and the amount of phenolic compounds increased. With crude oil and Pseudomonas aeruginosa bacterium, shoot dry weight, chlorophyll (a), total chlorophyll and anthocyanins decreased wherase phenolic compounds, malodialdehyde and catalase enzyme activity increased. With 1% crude oil and Acinetobacter calcoaceticus bacterium, significant changes were seen in the parameters of growth. Photosynthetic pigment did not increase whereas anthocyanin, phenolic compounds, malodialdehyde and catalase activity increased. White Crude oil and the presence of both bacteria shoot dry weight and chlorophyll levels decreased and increased levels of anthocyanin and malon-dialdehyde were observed. Addition of oil to the soil, increased the numbers of crude oil degrading bacteria and heterotrophic bacteria but crude oil were removed from soil by biodegradation. By application of bacterialplant systems in the field, industrial wastes from refinery and biochemical factories could be removed oppropriately. [ABSTRACT FROM AUTHOR]

Introduction: Biofertilizers are the microorganisms that can convert useless nutrient to usable compounds. Unlike fertilizer, cost of biofertilizer production is low and doesn't produce ecosystem pollution. Phosphate fertilizers can be replaced by phosphate biofertilizer to produce improvement. So, it is necessary to screen the climate-compatible phosphate solubilizing bacteria. Materials and methods: In this project samples were picked up from Loriya hot spring, which are located in Jiroft. Samples were incubated in PKV medium for 3 days. Screening of phosphate solubilizing bacteria was performed on the specific media, based on clear area diameter. The best bacterium was identified based on 16s rDNA gene. Phosphate solubilizing activity of this strain was considered in different carbon, nitrogen, phosphate and pH sources. Results: Sequence alignment and phylogenetic tree results show that B. sp. LOR033 is closely related to Bacillus licheniformis, with 97% homology. In addition, results show that maximum enzyme production was performed after 2 days that incubation pH was decreased simultaneously when the time was increased. Carbon sources investigation show that glucose is the most appropriate in enzyme production and phosphate releasing. Furthermore, results show that the optimum initial pH for phytase production was pH5.0. Different phosphate sources show that tricalcium phosphate has the suitable effect on enzyme activity in three days of incubation. Discussion and conclusion: Phosphatase enzyme production capacity, growth in acidic pH and phosphate solubilizing potential in different salt and phosphate sources show that this strain has considerable importance as biofertilizers. [ABSTRACT FROM AUTHOR]