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Alcohol-Based Biofuel Cells
Published in Shelley Minteer, Alcoholic Fuels, 2016
Sabina Topcagic, Becky L. Treu, Shelley D. Minteer
More recent research in developing long-term stability in biofuel cell systems has focused on studying a new enzymatic system. Initial studies have been successful in utilizing PQQ-dependent ADH as a catalyst at the anode of a biofuel cell. Pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) has been chosen to replace NAD+-dependent ADH in order to extend the lifetime and simplicity of the fuel cell. PQQ is the coenzyme of PQQ-dependent ADH, and it remains electrostatically attached to PQQ-dependent ADH; therefore, the enzyme and coenzyme will remain in the membrane leading to an increased lifetime and activity for the biofuel cell. Also, PQQ-dependent ADH possesses desirable electrochemistry (it has the ability to transition between its oxidized and reduced state). The coenzyme PQQ has quasireversible electrochemistry and a low overpotential at an unmodified carbon electrode. This eliminates the need for an electrocatalyst layer, thereby simplifying the process of forming high-surface-area bioanodes.
Vinegar from Bael (Aegle marmelos): A Mixed Culture Approach
Published in Indian Chemical Engineer, 2018
Kaustav Chakraborty, Suman Kumar Saha, Utpal Raychaudhuri, Runu Chakraborty
Traditionally, industrial vinegar has been produced with sequential submerged fermentation processes catalysed by yeast and bacteria respectively [13]. Industrially, fed batch process is primarily used, for its ability to reduce the risk of substrate inhibition and catabolite repression and produce high-acid content. Availability of suitable alcoholic stock, uninterrupted aeration and high-acid tolerance are the key basic requirements for the submerged acetous fermentation process [14]. Ethanol fermentation is an anaerobic process, whereas, oxidation of ethanol to acetic acid is catalysed by a membrane bound pyrroloquinoline quinone-dependent alcohol dehydrogenase (PQQ-ADH) and aldehyde dehydrogenase (ALDH) [15]. Both dehydrogenase complexes are linked to the respiratory chain, which uses oxygen as final oxygen receptor. Incompatibility between two process’ oxygen requirements remains the key stumbling block to the use of mixed culture in the commercial vinegar making. In this study, batch mode had been used which required lesser oxygen than continuous and semi-continuous mode [14].
Enhancing integrated denitrifying anaerobic methane oxidation and Anammox processes for nitrogen and methane removal: A review
Published in Critical Reviews in Environmental Science and Technology, 2023
Yan Chen, Guangming Jiang, Muttucumaru Sivakumar, Jiangping Wu
The integrated DAMO–Anammox process has a great potential in achieving energy-positive wastewater treatment, through its environmentally friendly and economical nitrogen removal from wastewater. However, culturing DAMO microorganisms and Anammox bacteria has been a challenge due to their extreme slow growth rate (Table 2). The long doubling time of them is attributed to different reasons: the high energy requirement to break the C–H bond for DAMO archaea, the lack of cell membrane for pMMO and genes of pyrroloquinoline quinone (PQQ: a growth-promoting agent for stimulating microbial growth) biosynthesis in DAMO bacteria (Hatamoto et al., 2018), and the hzs enzyme for Anammox bacteria (Kartal et al., 2013; Kuenen, 2008).
Comparative assessment of blood glucose monitoring techniques: a review
Published in Journal of Medical Engineering & Technology, 2023
Nivad Ahmadian, Annamalai Manickavasagan, Amanat Ali
SMBG devices have three main parts, a lancet, a test strip, and a metre. The strip is the second-generation mediator biosensor. Thereby, the measuring method is based on electrochemical reactions taking place in the connected test strip to the metre. Although glucose oxidase (GOx) is the most usable and reliable enzyme in many devices, some devices utilise glucose dehydrogenase (GDH) coupled with a coenzyme of pyrroloquinoline quinone (PQQ) or Flavin-adenine dinucleotide (FAD) [26]. The amount of glucose in the sample of blood drop oxidises with the enzyme and generates a current. The current is then converted to a voltage that is proportional to the blood glucose concentration [27].