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Heterologous Gene Expression in Ci Compound-Utilizing Yeasts
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
The unicellular eukaryotic yeasts combine the ease of genetic manipulation and fermentation procedures with the ability to modify proteins in the eukaryotic manner. Therefore, yeasts provide attractive hosts for the expression of heterologous proteins. As a well-known traditional industrial organism, the baker’s yeast represented the first example. An increasing number of alternative non-Saccharomyces species exhibit the potential of excellent expression systems. As such, the two methylotrophic species H. polymorpha and P. pastoris represent advanced developments for industrial application. The characteristics of the methylotrophic yeasts summarized in this chapter confirm that they are useful expression systems and, in many instances, the systems of choice for the production of a recombinant protein.
Selenate and thiosulfate reduction using methanol as electron donor
Published in Tejaswini Eregowda, Anaerobic treatment and resource recovery from methanol rich waste gases and wastewaters, 2019
Methylotrophic microorganisms utilize methanol as the substrate for methane and VFA production. They play a key role in the anaerobic treatment of effluents rich in alcohols and sugars (Large, 1983). The effect of several inhibitory factors on the anaerobic digestion of methanol, including high concentrations of ammonia, sulfide and heavy metals have been reported in the literature (Chen et al., 2008). However, to the best of our knowledge, the effects of oxyanions such as selenate (SeO42−) and thiosulfate (S2O32−) have not yet been reported. Selenium (Se) is a chalcogen (group 16 of the periodic table) and a trace element naturally present in bed rocks. Although Se is an essential element (at <40 μg/d), an intake >400 μg/d can be toxic to the living organisms (Bleiman and Mishael, 2010). Se shares similar physico-chemical properties with sulfur and is closely associated with sulfur-containing minerals, pyrites and fossil fuel sources (Mehdi et al., 2013). Due to its chalcophilic nature, i.e. strong affinity with sulfur (Tan et al., 2016), Se compounds have a close analogy with sulfur compounds (Mehdi et al., 2013) and the biochemical similarities of Se and sulfur allow their exchange by sulfate and selenate reducing organisms (Hockin and Gadd, 2003a).
Comparative assessment of modeling and experimental data of ammonia removal from pre-digested chicken manure
Published in Journal of Environmental Science and Health, Part A, 2020
Goksen Pekyavas, R. Kaan Dereli, Cigdem Yangin-Gomec
In this study, the UASB reactor was modeled by using GPS-X 6.5 simulation software which includes several built in model libraries, aerobic and anaerobic processes, and various units commonly used in wastewater treatment plants. The software has a user friendly, drag and drop interface and it offers several tools for model optimization and parameter estimation. The reactor was represented by using a UASB object, which includes reactor hydraulics and gas-solid-liquid (GSL) separator typical for the high rate up-flow reactors, in the software (Figure 2). The biochemical processes within the UASB reactor were represented by using Mantis2 model which is a super model that includes 56 processes and 48 state variables.[26] The model consists of carbon, nitrogen and phosphorus removal processes under aerobic, anoxic and anaerobic conditions, including two-step nitrification using AOB and NOB, two-step denitrification, methanol degradation process with methylotroph biomass, Anammox process, etc. The model was calibrated with the data acquired from the UASB reactor for an operating period of 152 days[19] and descriptive statistics of the data collected are given in Table 1.