An Overview of Protease Inhibitors
Se-Kwon Kim in Marine Biochemistry, 2023
Actinomycetes are bacteria that are nonmotile, aerobic, and gram-positive G+C (70 to 80%) and that have a relationship with bacteria based on 16s ribosomal arrangement studies. They are members of the Actinomycetales order, which produces substrate mycelium as well as aerial mycelia and spores. Aerial mycelium spore-bearing hyphae are slightly larger than substrate mycelium hyphae. Actinobacteria’s aerial mycelium produces sporophores with a variety of structures. The spores are unaffected by drying and can live in soil for lengthy periods. This phase of the life cycle confers resilience to the soil’s harsh environmental conditions, such as nutrient deficiency and water scarcity. Actinobacteria have a wide range of phenotypes and can be found in a variety of natural settings (Williams et al., 1983). They show a crucial part in the production of a wide range of medications that are vital for our nutrition and health. Actinobacteria, primarily the species Streptomyces and Micromonospora, are known to be the source of about 60–70% of the antibiotics available in the world (Jensen et al., 1991). The list of antibiotics produced by several Actinobacteria with excellent antibacterial activity is shown in Table 19.3.
Factors Affecting the Microflora of the Lower Genital Tract of Healthy Women
Michael J. Hill, Philip D. Marsh in Human Microbial Ecology, 2020
The use of oral contraceptives with the resultant effect on hormone levels would be expected to produce changes in the microflora. This has not been studied in any depth but in most studies women using oral contraception are excluded. The use of an intrauterine device has been associated with changes in vaginal microflora,17 including an association with the presence of Actinomyces israelii.73–75 Actinomycetes usually occur with a mixed anaerobic microflora and are identified by the presence of sulfur granules on microscopy or in routine cervicovaginal Papanicolou smears.76 Culture is often unsuccessful. Colonization appears to be more common among women using plastic devices rather than copper suggesting some protective effect by the copper.77 Most reports suggest that actinomycetes cause a chronic, low-grade endometritis, although tuboovarian abscesses have been described.75 The presence of a foreign body is known to potentiate infections caused by organisms of low virulence and hence these findings are not surprising. A summary of factors affecting the composition of the microflora of the lower genital tract is shown in Table 6.
Tropical Colorectal Surgery
Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams in Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Actinomycetes are usually avirulent microrganisms, and they seldom cause disease. They become pathogenic through invasion or a break in the integrity of mucous membranes and in the presence of devitalised tissue. Once infection is established, the host mounts an inflammatory response with granulation and suppuration ultimately resulting in the formation of abscesses, fistula and sinus tracts86 that may discharge sulphur granules. Factors that predispose to abdominal actinomycosis include abdominal operations, abdominal trauma or a perforated viscus. Abdominal actinomycosis is most frequently seen at the ileocaecal region where it typically presents as a slowly growing tumour. The diagnosis is usually established post-operatively following an exploratory laparotomy for a suspected malignancy.
Maculosin, a non-toxic antioxidant compound isolated from Streptomyces sp. KTM18
Published in Pharmaceutical Biology, 2021
Babita Paudel, Rukusha Maharjan, Prajwal Rajbhandari, Niraj Aryal, Saefuddin Aziz, Keshab Bhattarai, Bikash Baral, Rajani Malla, Hari Datta Bhattarai
Streptomyces are Gram-positive bacteria that are found in various environmental conditions and have a filamentous mycelium similar to fungi. Phylogenetically, Streptomyces is a part of Actinobacteria, with high GC-rich (70%) content. Most of them are ubiquitous and highly versatile soil-dwelling saprophytes known to produce diverse secondary metabolites, many of which are well-known antibiotics (Omura et al. 2001; Khan et al. 2011). Antioxidant activities of 30 strains of rare Actinomycetes were reported (Mohammadipanah and Momenilandi 2018) without characterizing the active molecules. Similarly, the broth extract of Streptomyces carpaticus displayed a significant DPPH free radical scavenging activity (IC50, 84.5 µg/mL) (Subramanian et al. 2017); however, the active molecule was not characterized. Thus, besides antibiotics, Streptomyces could be a promising source of antioxidant compounds.
Biofouling in membrane bioreactors: nexus between polyacrylonitrile surface charge and community composition
Published in Biofouling, 2018
Lisendra Marbelia, Marie-Aline Hernalsteens, Shazia Ilyas, Basak Öztürk, Anthony Szymczyk, Dirk Springael, Ivo Vankelecom
Based on Figure 2, it may be stated that the planktonic community of activated sludge differs significantly from that of the protamylasse feed, and both differ significantly from the sessile community of the membrane biofilms, independently of the sampling time point or on the membrane type. Among other publications (Zhang, Choi, et al. 2006; Jinhua et al. 2006), Huang et al. (2008) and Piasecka et al. (2012) observed that most of the OTUs detected in planktonic biomass were not detected in the biofilm fingerprints (Huang et al. 2008; Piasecka et al. 2012), or at least not in the same relative abundance (Miura et al. 2007). While the α-, β-, γ- and δ-Proteobacteria are the dominant species found in biofilms, the activated sludge communities of both aerobic and anaerobic MBRs were reported to be dominated by α-, β- or γ-Proteobacteria (Wagner et al. 1994; Boon et al. 2002; Piasecka et al. 2012) (eg Pseudomonas sp. which is reported to always be present in activated sludge (Khan et al. 2013; Waheed et al. 2013)), Bacteroidetes (Wan et al. 2011; Piasecka et al. 2012) and Gram-positive bacteria characterized by a high G+C DNA content (generally > 50%) (Wagner et al. 1994). The latter include the class Actinobacteria and more specifically the filamentous actinomycetes (Boon et al. 2002; Ventura et al. 2007), to which M. parvicella, a filamentous bacterium predominant in sludge belongs (McIlroy et al. 2013). Most of these abundant planktonic bacteria have not been observed to colonize membrane surfaces, which may explain the differences in the planktonic and membrane-associated communities in the present experiments.
Carbazole scaffolds in cancer therapy: a review from 2012 to 2018
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Samar Issa, Anthony Prandina, Nicolas Bedel, Pål Rongved, Saïd Yous, Marc Le Borgne, Zouhair Bouaziz
Isolated from the marine-derived actinomycetes strain Streptomyces sp. FMA, streptocarbazoles A and B (Figure 62) were tested as anti-tumoural agents. Streptocarbazole A was cytotoxic against HL-60, A-549 (lung carcinoma), P388 (leukaemia) and HeLa cell lines, with IC50 values of 1.4, 5.0, 18.9 and 34.5 µM, respectively, and could arrest the cell cycle of HeLa cells at the G2/M phase (at a concentration of 10 µM). Streptocarbazole B was only active against P388 and HeLa cells, demonstrating IC50 values of 12.8 and 22.5 µM, respectively95.
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