Isolation and Characterization of Potential Antibiotic-Producing Actinomycetes from Water and Soil Sediments of Different Regions of Nepal

Abstract

Introduction. The actinomycetes are diversely distributed microorganisms in nature. The geographical diversity of Nepal is suitable for adaptation of various species of actinomycetes. The distribution of the actinomycetes is dependent upon the altitude and nature of the soil and water. Methods. A total of 22 water and soil samples were collected from different regions of Nepal and were processed. Different isolates were characterized by observing colony characteristics and microscopic characteristics. Screening of the antimicrobial property was based upon perpendicular line streaking and submerged-state fermentation for antibiotic production. Results. From the identification tool used, 12 were found to be Micromonospora, 9 were Nocardia, and 7 were Streptomyces. Out of total samples, 8 isolates of actinomycetes were tested effective against the tested bacteria by primary screening using the well diffusion method. Among the primarily screened, all isolates were subjected to submerged-state fermentation methods to produce crude extracts and 4 were found to be effective against the tested bacterial group. The actinomycetes identified from a water source showed better antimicrobial property towards the tested bacteria than the soil sample. Most isolates were found to be Micromonospora followed by Nocardia and Streptomyces with higher antimicrobial activities. Conclusion. The water source and soil sediments of Nepal provide suitable environments for actinomycetes towards obtaining a novel antimicrobial agent. The study of actinomycetes from various unexploited areas of Nepal is necessary. Thus, exploitation of various regions of Nepal for the discovery of an effective antimicrobial agent is helpful in providing a solution to the cost-effective therapy and action against antibiotic resistance.

In Vitro Antitumor Activity of Endophytic and Rhizosphere Gram-Positive Bacteria from Ibervillea sonorae (S. Watson) Greene against L5178Y-R Lymphoma Cells

“…In the present study, we isolated different strains of Bacillus , which relates to other reports, showing the presence of these bacteria in 50% of endophytes from cucurbitaceous plants [ 33 ]. We also isolated various species of Micromonospora from the rhizosphere, such as M. echinospora , M. inositola, and M. terminaliae , which are commonly found in marine sediments, probably due to the area of plant collection on the southern coast shores of the state of Sonora [ 34 , 35 ].…”

Antimicrobial Potential of Streptomyces spp. Isolated from the Rift Valley Regions of Ethiopia

“…This could be due to impurities in the extract or impurities in the extract obstructing extract diffusion in the agar plates, lowering the bioactivity of the extracts. The metabolites from these isolates could be purified further to get their effectiveness and composition to compare with a pure antibiotic drug that was already in clinical use, as reported earlier in [ 18 , 22 ].…”

“…The inoculum was prepared and standardized to the density of the screening test done by the method described in [ 22 ]. A loopful colonies of test pathogens from fresh culture were transferred to test tubes containing sterile saline (0.85%) and used to match turbidity equivalent to 0.5 McFarland standards which are equivalent to a cell density of 10 6 –10 8 CFU/mL for bacteria, whereas 2.5 × 10 3 CFU/mL for fungi was used.…”

“…Solvent extraction of the bioactive metabolite from the selected actinomycetes isolates which exhibit a broad-spectrum activity in primary screening was done by liquid-state fermentation as described in [ 22 , 23 ] with some modifications. Briefly, two milliliters from each fresh culture were transferred into 100 mL of (ISP-2 broth) yeast extract malt extract dextrose broth in conical flasks under sterile conditions and were placed into a shaking incubator at 28 ± 2°C for 8 days.…”

Structural Characterization, Antimicrobial, Antibiofilm, Antioxidant, Anticancer and Acute Toxicity Properties of N-(2-hydroxyphenyl)-2-phenazinamine From Nocardiopsis exhalans (KP149558)

“…Microbial diversity aids to build a new generation of unique structures, enabling a beneficial source for novel pharmaceuticals and other high-value products ( Abdel-Razek et al., 2020 ). An ample quantity of valuable bioactive constituents and drugs has been identified from terrestrial microorganisms ( Shrestha et al., 2021 ); however, studies in this area have reduced due to the feeling that this resource has been fully harvested. Therefore, researchers focus on the marine-derived antibiotics to develop new therapeutic applications for the modern world.…”