Background: Alginate is a linear polysaccharide consisting of guluronate (polyG) and mannuronate (polyM) subunits. Methods: In the initial screening of alginate-degrading bacteria from soil, 10 isolates were able to grow on minimal medium containing alginate. The optimization of cell growth and alginate lyase (algL) production was carried out by the addition of 0.8% alginate and 0.2-0.3 M NaCl to the culture medium. Of 10 isolates, one was selected based on its fast growth rate on minimal 9 medium containing 0.4% sodium alginate. The selected bacterium, identified based on morphological and biochemical characteristics, as well as 16S rDNA sequence data, was confirmed to be an isolate belonging to the genus Bacillus and designated as Bacillus sp. TAG8. Results: The results showed the ability of Bacillus sp. TAG8 in utilizing alginate as a sole carbon source. Bacillus sp. TAG8 growth and algL production were augmented with an increase in sodium alginate concentration and also by the addition of 0.2-0.3 M NaCl. Molecular analysis of TAG8 algL gene showed 99% sequence identity with algL of Pseudomonas aeruginosa PAO1. The algL produced by Bacillus sp. TAG8 cleaved both polyM and polyG blocks in alginate molecule, as well as acetylated alginate residues, confirming the bifunctionality of the isolated lyase. Conclusion: The identification of novel algL genes from microbial communities constitutes a new approach for exploring lyases with specific activity against bacterial alginates and may thus contribute to the eradication of persistent biofilms from clinical samples.
Periodontal disease is one of the most prevalent infectious oral conditions in the present century, and it is necessary to conduct research to find a solution to overcome these diseases. A variety of microbial strains of bacteria and fungi are involved in the pathogenesis of periodontal disease. The use of chemical agents such as mouthwashes is one of the strategies to control these diseases. The purpose of the present study was to compare the antimicrobial effects of propolis and chlorhexidine gluconate (CHX) on the bacterial strains of Streptococcus mutans, Streptococcus pyogenes, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and the yeast strain of Candida albicans using the broth microdilution method. The results showed the inhibitory and microbicidal activities of the two substances against the tested microbial strains. The antibacterial and antifungal effects of CHX were more effective reported in this study than that of propolis against the studied pathogens. The results of this study also indicated that the propolis was less effective in inhibiting bacterial growth than the CHX. In addition, the combination of these two solutions had a synergistic effect on inhibition of other studied strains, with the exception of C. albicans and S. aureus. There is a need for further research on strains isolated from oral biofilm to achieve complementary results.
Nowadays, in the poultry industry, antibiotics are used to treat, prevent, and enhance poultry growth and production efficiency. Their irregular consumption has resulted in the spread of antibiotic-resistant bacteria in this industry. Antibiotic-resistant bacteria in contaminated waters can be transmitted into soil. The purpose of this study was to investigate the antibiotic resistance pattern of bacteria isolated from the water of chicken slaughterhouses around Hamadan (Iran) province. In this study, 20 water samples were collected from four slaughterhouses in Hamadan province (during spring and summer 2019). Initial isolation and identification of the bacteria were performed by pour plate culture and biochemical tests. The disc diffusion method was applied to investigate the resistance pattern. This study presents 109 screened isolates. Of these, 57.8% E.coli, 35.7% Salmonella spp., and 6.42% Klebsiella spp. were detected. Antibiograms of isolates showed that in E.coli, 23.09% were resistant to four types of the antibiotic tetracycline, amoxicillin, gentamicin, and chloramphenicol, 76.19% had only one type of antibiotic. Antibiotics for Salmonella spp. showed that 35.9% were resistant to tetracycline, gentamicin, and chloramphenicol, 64.10% to only one type of antibiotic. Also, in Klebsiella spp., 85.71% were sensitive to antibiotics, and only 14.28% were resistant to tetracycline. Conclusion: The results showed that the rate of multiple antibiotic resistance is relatively high, and contaminated water has a high potential for soil contamination. Therefore, resistant bacteria become more stable in the environment, and the health of the environment will be endangered. Therefore, it is necessary to study the antimicrobial resistance patterns of bacteria to study and maintain the health of the environment.
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