Nanotechnology is a new emerging interdisciplinary approach created by pairing of engineering, chemical, and biological approaches. This technology produces nanoparticles using different methods of traditional physical and chemical processes; however, the outlook in this field of research is to use ecofriendly, nontoxic, and clean methods for the synthesis of nanoparticles. Biological entities, such as plants, bacteria, fungi, algae, yeast, and actinomycetes, are the best candidate to achieve this goal. Among the biological route, those involve endophtic microorganisms to reduce metallic ions into nanoparticles. This method is considered as an attractive option and can open a new horizon on the interface of biology and nanotechnology. The present chapter highlights the latest research about endophytic microorganisms and their application in the synthesis of nanoparticles, as well as the mechanisms involved in the formation of nanoparticles.

ObjectiveTo study the antimicrobial activity of actinomycetes isolated from sabkha of Kenadsa and identification of the isolate interesting.MethodsEighteen strains were isolated, using four culture media from sebkha of Kenadsa (Bechar, Southwestern Algeria). Screening of antimicrobial activity consisted of two steps: in primary screening, antibacterial activity was determined by using the agar plug method against test strains; in secondary screening, better isolate which showed a good activity in the first screening was selected to extract antimicrobial substances. The antimicrobial activities of extracts were evaluated by using Kirby–Bauer disc diffusion method. Partial characterization of antimicrobial products was performed on the basis of chemical revelations, UV–vis spectrometry and infrared spectroscopy. The identification of isolate interesting was performed through morphological, chemical, biochemical and physiological characteristics.ResultsAll isolates showed antimicrobial activity against at least one microorganism test. One isolate, LAM143cG3, was selected for its broad spectrum and high antimicrobial activity. The isolate LAM143cG3 was identified as Spirillospora sp. The comparison between the species of this genus (Spirillospora rubra and Spirillospora albida) and our isolate indicated the existence of several physiological and biochemical differences which led us to suppose that this was a new member of this genus. Primary characterization of antimicrobial substances produced by the isolate LAM143cG3 indicated the presence of amines and phenols. The UV–vis spectrum suggested a non-polyenic nature of substances secreted by our isolate, while infrared confirmed the presence of amine groups.ConclusionsThe result of the present study revealed that sebkha of Kenadsa was rich in rare actinomycetes, that secreted interesting antimicrobial substance

• Anthocyanins as potential inhibitors of the coronavirus. • Main protease and spike glycoprotein of SARS-CoV-2. • Molecular docking and MD simulation. • Cyanidin-3-arabinoside is a potent inhibitor of SARS-COV-2.

The diversity of cultural Actinobacteria in two types of Algerian Sahara environments, including saline environments and date palms rhizosphere, was investigated. In this study, a total of 40 strains of actinomycetes was isolated from different soil samples, using a rehydration and centrifugation method. Molecular identification, based on 16S rRNA gene sequence analysis, revealed that these isolates were affiliated to six clusters corresponding to eight genera, including Streptomyces, Nocardiopsis, Saccharopolyspora, Actinomadura, Actinocorallia, Micromonospora, Couchioplanes, and Planomonospora. A taxonomic analysis, based on the morphological, physiological, biochemical, and molecular investigation, of selected strains, which belong to the rare Actinobacteria, was undertaken. Four strains (CG3, A111, A93, and A79) were found to form distinct phyletic lines and represent new actinobacterial taxa. An assessment of antimicrobial proprieties of the 40 obtained actinomycetes strains, showed moderate to strong antimicrobial activities against fungi and bacteria. This study demonstrated the richness of Algerian Sahara with rare Actinobacteria, which can provide novel bioactive metabolites, to solving some of the most challenging problems of the day, such as multi-drug resistance.

Bacterial resistance to different antimicrobial agents is growing with alarming speed, especially when bacterial cells are living in biofilm. Hybrid nanoparticles, synthesized through the green method, hold promise as a potential solution to this challenge. In this study, 66 actinomycete strains were isolated from three distinct marine sources: marine sediment, the algae Codium bursa, and the marine sponge Chondrosia reniformis. From the entirety of the isolated strains, one strain, S26, identified as Saccharopolyspora erythrea, was selected based on its taxonomic position and significant antimicrobial activity. Using the biomass of the selected marine Actinobacteria, the green synthesis of eco-friendly silver carbonate nanoparticles (BioAg₂CO₃NPs) is reported for the first time in this pioneering study. The BioAg₂CO₃NPs were characterized using different spectroscopic and microscopic analyses; the synthesized BioAg₂CO₃NPs primarily exhibit a triangular shape, with an approximate size of 100 nm. Biological activity evaluation indicated that the BioAg₂CO₃NPs exhibited good antimicrobial activity against all tested microorganisms and were able to remove 58% of the biofilm formed by the Klebsiella pneumoniae kp6 strain.