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Polymeric Membranes for Biomedical and Biotechnology Applications
Published in Chandan Das, Kibrom Alebel Gebru, Polymeric Membrane Synthesis, Modification, and Applications, 2018
Chandan Das, Kibrom Alebel Gebru
Membrane filtration is also particularly well suitable in antibiotic production where most antibiotics, such as erythromycin, benzylpenicillin (penicillin G), and medmycin, are broadly employed and also used as raw materials for semisynthetic antibiotics. Then, these are produced by fermentation and recovered from their broths by using the conventional steps, like solvent extraction (isolation and purification), filtration (removal of biomass), and subsequent crystallisation (polish). Therefore, membrane filtration is used for the primary clarification of these fermentation broths [250–252]. One of the main advantages of membrane systems for the initial recovery of antibiotics from a fermentation broth is the ability to obtain high yield using a combined filtration and diafiltration process. Complete retention of the cells and particulate matter can be achieved using membranes with pore sizes up to 0.2–0.45 μm, and essentially complete passage of the antibiotics can be achieved as long as the nominal membrane molecular cut-off is greater than about 20,000 g/mol [245]. Ultrafiltration was used to remove emulsifiers in antibiotic broths before solvent extraction to avoid emulsification and to improve extraction efficiency. Purification of benzylpenicillin filtered broths obtained from fermented broths by ultrafiltration with diafiltration was also reported by Nabais and Cardoso (1999) [251]. The authers have conducted an investigation using pilot ultrafiltration process with a tubular membrane and membranes with molecular weight cut-off of 100,000 (PVDF), 20,000 (polysulfone), and 8000 (polysulfone) were investigated. The colored substances, proteins, and other impurities were effectively removed, and high benzylpenicillin recovery in permeate was also detected. Moreover, it was demonstrated that ultrafiltration may be an alternative to the use of flocculants and anti-emulsion agents to attain good phase separation in benzylpenicillin solvent extraction.
Antibiotic residues in the aquatic environment – current perspective and risk considerations
Published in Journal of Environmental Science and Health, Part A, 2021
Ciaran Monahan, Rajat Nag, Dearbháile Morris, Enda Cummins
As summarized in Fig. 3, antibiotics administered in healthcare and agriculture follow a similar pathway to environmental matrices via excretion through urine or feces. Oral bioavailability describes the percentage of a compound which, when taken orally, is absorbed in the GI tract. Bioavailability varies between antibiotics, but they generally have relatively low bioavailability in both humans and animals. Within the same class, antibiotics can have significantly different rates of gastrointestinal uptake due to small differences in structure. For example, benzylpenicillin (penicillin G) has a bioavailability of roughly 30% after oral administration in humans, whereas phenoxymethylpenicillin (penicillin V) has a bioavailability of between 60-70%.[16] Due to generally high excretion rates, a large percentage of the antibiotics administered in healthcare and agriculture are excreted in feces and urine.