China
Africa
Explore chapters and articles related to this topic
Antibiotics: The Battle with the Microbes
Published in Richard J. Sundberg, The Chemical Century, 2017
The first antibiotic that was found to be active against tuberculosis was streptomycin, an aminoglycoside isolated in the laboratory of Selman Waksman,e a soil microbiologist at Rutgers University. One of his collaborators, Rene Dubos,fwas interested in the mechanism by which microorganisms could break down cellulose and proteins in the soil. He devised a technique for finding the most promising organism by isolating those that grew best on the material. In 1927, Dubos moved to the Rockefeller Institute in New York, where he worked with Oswald Avery (see Section 20.1 for biography). Avery was interested in the polysaccharide that encapsulates the organism Pneumococcus responsible for pneumonia. Dubos examined soil samples to locate microorganism that might attack the Pneumococcus capsule. An extract from one such organism protected mice against Pneumonoccus. Collaborating with chemist Rollin Hotchkiss in 1939, they isolated the active compound gramicidin from Bacillus brevis. Gramicidin is a modified polypeptide containing several d-Val and d-Leu amino acids. The material was produced in conjunction with Merck. Gramicidin proved too toxic for oral or intravenous treatment, but it could be used on open wounds by topical administration.
Studies on a new antimicrobial peptide from Vibrio proteolyticus MT110
Published in Preparative Biochemistry & Biotechnology, 2023
Himanshu Verma, Kanti N. Mihooliya, Jitender Nandal, Debendra K. Sahoo
Antimicrobial peptides (AMPs) are short-cationic and amphiphilic molecules because of hydrophobic and positively charged residues, and some of these AMPs are known to exhibit immunomodulatory activity.[1,2] Many naturally occurring AMPs are found in diverse forms of life (e.g., http://aps.unmc.edu/AP/main.php), and being a part of the innate immune system, these peptides are also called natures antibiotics.[3] AMPs, though produced by every form of life, show immense diversity in sequence and antimicrobial activity because of differences in the pathogenic challenges and virulence strategy the producer organisms face. Generally, AMPs show broad-spectrum activity against Gram-positive and Gram-negative bacteria, viruses, parasites, and fungi. However, only a few AMPs are used for medicinal purposes (such as polymyxin B and gramicidin S) because of their broad-spectrum and weakened antimicrobial activity under physiological conditions.[1,4]
The purification and functional study of new compounds produced by Escherichia coli that influence the growth of sulfate reducing bacteria
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Oluwafemi Adebayo Oyewole, Julian Mitchell, Sarah Thresh, Vitaly Zinkevich
Several studies have described some inhibitors of SRB growth that are derived from bacteria; for example, Jayaraman et al. [69] and Zuo [29] reported that indolicidin, bactenecin, and polymyxin produced by Paenibacillus polymyxa are capable of inhibiting SRB growth. Bacillus brevis produces a compound referred to as gramicidin-S that inhibits the growth of Desulfovibrio orientis, D. vulgaris and D. gigas [29,31,70] and thereby reduced corrosion caused by the SRB. In addition, Bacillus licheniformis secretes γ-polyglutamate and polyaspartate that reduce SRB growth [29,71,72]. The mechanism of SRB growth prevention by these organisms has been suggested and include either the production of antimicrobial agents [29,73] or attack on the adenosine 5ʹ- phosphosulphate (APS) and bisulfate reductase (DSR) responsible for hydrogen sulfide production in SRBs [14]. Similarly, the SGE may function in SRB induction by increasing their growth rate while the SGI may function by causing damage in the cells as observed in this study. The MALDI-TOF spectra showed the presence of low molecular weight compounds in the range of 1700 Da for SGE and 2400 Da for SGI. The spectra showed equal and repeating units of ~213 m/z between the peaks. According to Wallace and Guttman [74], the equal and repeating units are characteristic spectra of condensation homopolymers. MALDI-TOF spectra revealed that the compounds are small molecular weight biomolecules and that the two molecules are very closely related.
An eco-friendly approach to biosurfactant production using low-cost wastes
Published in Journal of Dispersion Science and Technology, 2023
Kaan Soyuer, Sezen Bilen Ozyurek
Microbial biosurfactants, which can be composed of lipids, glycolipids, lipopeptides and/or polysaccharide-protein complexes, are secondary metabolites with antagonistic effects. Among the lipopeptide biosurfactants, surfactin and iturin are produced by Bacillus subtilis, lichenis by B. licheniformis, serravettin by Serratia marcescens, viscosine by P. fluorescens, gramicidin by B. brevis, and polymyxin by B. polymyxa.[91] In particular, Bacillus species are known to produce secondary active metabolites such as broad-spectrum lipopeptide biosurfactants with antimicrobial properties.[92,93] The antimicrobial mechanisms of biosurfactants, which differ from conventional antibiotics, are generally based on degradation of bacterial cells by disrupting the integrity of the plasma membrane or cell wall.[94,95] Accordingly, the antimicrobial activities of biosurfactant against different Gram-negative and Gram-positive bacterial strains were shown in Table 4. So, it was detected that the biosurfactant was quite effective against both Gram-negative and Gram-positive bacteria according to the results of inhibition zone diameters. Not only its antimicrobial activity against E. coli was quite high but also it was more effective than penicillin and gentamicin antibiotics against E. coli strain. Moreover, the antimicrobial activity of biosurfactant against whole bacterial strains was close to that of gentamicin. Similarly, an antibacterial activity of biosurfactant against S. aureus, E. coli and K. pneumonia was found.[78] They also reported that the inhibition zone diameter was found to be larger for E. coli than for S. aureus. As similar to our study, it was reported that in addition to being effective of the surfactin extracted from Bacillus amyloliquefaciens ST34 against all tested Gram-negative bacteria, it has also an antimicrobial activity against antibiotic resistant Staphylococcus aureus and Escherichia coli strains.[48]