ng of cells is a more likely explanation for this finding than different initial Bacillus densities. The importance of spatial structure seen in this study is consistent with a terrestrial rather than an aquatic distribution of antibiotic-producing bacteria, and may have implications in the search for novel antibiotics.
Over the last 40 years, there has been a steady supply of novel, useful antibiotics produced by microbes isolated from soil and other natural environments. The increased efficiency of screening procedures in the last decade has played a major part in maintaining this supply. However, the selection and sampling of natural environments are still essentially random processes. The main reasons for this are an almost total lack of knowledge of the significance of antibiotics in nature, deficiencies in the taxonomy of antibiotic-producing microbes and its application, and lack of information about the distribution and ecology of known or potential antibiotic producers. The origins of these problems are discussed and some possible solutions are suggested.
A new perspective on the topic of antibiotic resistance is beginning to emerge based on a broader evolutionary and ecological understanding rather than from the traditional boundaries of clinical research of antibiotic-resistant bacterial pathogens. Phylogenetic insights into the evolution and diversity of several antibiotic resistance genes suggest that at least some of these genes have a long evolutionary history of diversification that began well before the antibiotic era. Besides, there is no indication that lateral gene transfer from antibiotic-producing bacteria has played any significant role in shaping the pool of antibiotic resistance genes in clinically relevant and commensal bacteria. Most likely, the primary antibiotic resistance gene pool originated and diversified within the environmental bacterial communities, from which the genes were mobilized and penetrated into taxonomically and ecologically distant bacterial populations, including pathogens. Dissemination and penetration of antibiotic resistance genes from antibiotic producers were less significant and essentially limited to other high G + C bacteria.
Conclusion
Antibiotics are biotechnological products that inhibit bacterial growth or kill bacteria. They are naturally produced by microorganisms, such as fungi, to attain an advantage over bacterial populations lt; https: //boundless/definition/population/gt ;. Antibiotics are produced on a large scale by cultivating and manipulating fungal cells. Many antibacterial compounds are classified on the basis of their chemical or biosynthetic origin into natural, semisynthetic, and synthetic. Another classification system is based on biological activity. In this classification, antibiotics are divided into two broad groups according to their biological effect on microorganisms: bactericidal lt; https: //boundless/definition/bactericidal/gt; agents kill bacteria, and bacteriostatic lt; https: //boundless/definition/bacteriostatic/gt; agents slow down or stall bacterial growth. of some locally isolated actinomycetes for the production of antibiotic (s). A survey of four locally isolated Streptomyces strains for antibiotic production was carried out in static and shaken cultures. It was generally observed that the growth and antibacterial activity obtained in static cultutres were higher than shaken cultures. Streptomyces astreogriseus showed the longest incubation time (12 days) needed to obtain maximum antibacterial activity, while Streptomyces violatus showed a relatively short time (7-days) and produced the highest activity among the tested strains. Streptomyces violatus [30] was also characterised by its broader antibacterial activity, because it affected the growth of all the tested bacteria, showing a stronger activity on S. aureus and B. subtilis. Accordingly, S. violatus was selected for further investigation.Antibiotics are produced industrially by a process of fermentation, where the source microorganism is grown in large containers (100,000-150,000 liters or more) containing a liquid growth medium. Oxygen concentration, temperature, pH lt; # justify gt; References
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