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The Sustainable Production of Polyhydroxyalkanoates from Crude Glycerol
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Neha Rani Bhagat, Preeti Kumari, Arup Giri, Geeta Gahlawat
A large number of PHA-producing microbes can grow on CG in optimized environmental conditions and metabolize it into cell biomass and PHA biopolymer. The types of biodegradable PHA plastics that are commonly synthesized include poly(3-hydroxybutyrate) [P(3HB) or PHB], poly(3-hydroxyvalerate) (PHV), poly(3-hydroxyhexanoate) (PHHx), and PHA containing 3-hydroxy-2-methylbutyrate or 3-hydroxy-2-methylvalerate (3H2MV) [12]. Generally, PHA are produced by pure cultures through microbial fermentation, and because of this, the average production cost of green plastic increases, which is almost double the price of poly(vinylchloride) (PVC) production [34]. Crude glycerol-based PHA production could be done with mixed microbial cultures (MMC) and feast-famine approaches, which have lower operating costs [35,36]. MMC has emerged as a viable process to reduce the production cost of PHA processes. They offer several advantages compared with pure cultures, such as growth on a variety of industrial waste feedstocks, the possibility for axenic cultivation of microbes, and easy assimilation of the carbon substrate.
Microbiology of Metalworking Fluids
Published in Jerry P. Byers, Metalworking Fluids, Third Edition, 2018
In the laboratory, microbes are typically studied in pure (axenic) culture—populations descended from a single cell. Research based on axenic cultures yields a tremendous amount of useful information about cell physiology and chemistry. However, in MWF systems, other industrial environments, and natural environments, microbes rarely exist as axenic cultures. As noted in the introduction, the varied and complex interactions among different taxa that are present in an ecosystem affect the activities of the microbiome and its individual members, so that the net effects of the community differ substantially from those that would be predicted based on our knowledge about the physiology of the individual taxa within that community. A jigsaw puzzle provides a useful analogy. Consider the futility of attempting to assemble a 1000-piece puzzle when you have only a dozen pieces available. The following section elaborates on this critical concept.
Biotechnology Facilities
Published in Terry Jacobs, Andrew A. Signore, Good Design Practices for GMP Pharmaceutical Facilities, 2016
The most accurate term for describing bioburden-free operations in biotechnology facilities is aseptic. Aseptic operations are considered devoid of detectable bioburden. Processing in bioreactors is occasionally described as aseptic but is more accurately described as axenic. The term axenic refers to a culture that contains a single strain of living organism (as intended in a bioreactor) but is entirely free of all other contaminating organisms.
A review of microalgal cell wall composition and degradation to enhance the recovery of biomolecules for biofuel production
Published in Biofuels, 2023
Syafiqah Md Nadzir, Norjan Yusof, Norazela Nordin, Azlan Kamari, Mohd Zulkhairi Mohd Yusoff
The destruction of an organism’s tissues or cells by endogenous enzymes triggered by the release of digestive enzymes from secretory vesicles is referred to as autolysis or self-digestion. The activation of these enzymes in a microbial cell disrupts the cell. During the life cycle of microalgae, cell wall-degrading enzymes perform autolysis, which is a natural occurrence. But this is not the case in algal culture that is kept in continuous log phase by constant harvesting and addition of compensating media. Depending on the cell type and environmental stress, these lysis events can occur throughout the asexual and sexual life cycles [15]. Poor cultivation techniques with some cell death by autolysis are not desirable, as the products are substrates for contaminating bacteria and fungi. However, this contamination can be avoided by conducting the study under axenic conditions. The cell wall-degrading enzymes secreted by microalgae during self-digestion are strain-specific, making them ideally suited for degrading the unique cell wall composition. This process can occur naturally or be controlled, for instance by reducing or depleting nutrient concentrations or by applying high temperatures. This mechanism occurs during the phase of cell death or decline in algal growth.
The role of silver nanoparticles biosynthesized by Anabaena variabilis and Spirulina platensis cyanobacteria for malachite green removal from wastewater
Published in Environmental Technology, 2021
Gehan A. Ismail, Nanis G. Allam, Walaa M. El-Gemizy, Mohamed A. Salem
Two species of cyanobacteria were isolated from local wastewater treatment plant. The species were cultivated and purified according to the standard microbiological methods to obtain axenic algal cultures [31]. The cyanobacteria species were identified as Anabaena variabilis (Kütz) and Spirulina platensis (Gomont) according to Desikachary [32]. A. variabilis was cultivated in BG11 medium [33] and S. platensis in modified Zarrouk’s medium [34]. The cultures were grown under fluorescent light intensity of 45 µ mole photon m−2 s−1 at 28°C and provided with a mixture of dry air (97%) and CO2 (3%) using an air pump until reaching the end of the exponential phase of growth. To synthesise AgNPs, 50 ml of each cyanobacterial culture were homogenised for 15 min and then added to 50 ml of AgNO3 solution (10−3 M) [11]. The developed nanoparticles were collected by centrifugation at 5000 rpm for 15 min as the supernatant layer.
Marine sediment derived bacteria Enterobacter asburiae ES1 and Enterobacter sp. Kamsi produce laccase with high dephenolisation potentials
Published in Preparative Biochemistry & Biotechnology, 2021
Chiedu E. Edoamodu, Uchechukwu U. Nwodo
Genomic DNA was extracted from the axenic cultures using the Quick-DNA™ Fungal/Bacteria Miniprep Kit (Zymo Research, Catalogue No. D6005). A region of the 16S rRNA gene was amplified using universal primers presented in Table 1. The PCR products were run on a gel, and the gel was extracted with the zymoclean™ Gel DNA Recovery Kit (Zyme Research, Catalogue No D4001). The excised bands were sequenced forward and reversed (Nimagen, BrillantDye™ Terminator Cycle Sequencing Kit 3.1, BRD3-100/1000) and purified (Zymo Research ZR-96 DNA Sequencing Clean-up kit™, Catalogue No. D4050). Purified fragments were analyzed on ABI 3500 Genetic Analyzer. The CLC Bio-Main Workbench 7.6 was used for the examination of the files generated by ABI. Results were obtained by a BLAST search (http://blast.ncbi.nlm.nih.gov/Blast.cgi) for the most similar sequence strain. ClusterW of BioEdit was used to analyze the multiple sequence alignment. MEGA X was utilized to construct the phylogenetic tree with reference to the strains pulled from the NCBI database to show the relationship between retrieved bacteria sequence