Optimization of fermentation upstream parameters and immobilization of Corynebacterium glutamicum MH 20-22 B cells to enhance the production of l-lysine
Abstract:l-Lysine is an essential amino acid with high commercial importance, as it has to be available in sufficient quantities in animal and human feeds to meet their nutritional requirement. As there is constant increase in l-lysine demand every year, to meet the increasing demand it is necessary to produce l-lysine in large scale. Generally, l-lysine is produced by batch fermentation. In the present investigation, different fermentation process parameters such as fermentation time, pH, temperature, glucose concentr… Show more
“…Submerged culture is a key technology to obtain high yield liquid inoculant (Jafarzade et al 2013). Razak and Viswanath (2015) optimized the production of L-lysine using Corynebacterium glutamicum MH 20-22 B, which produced 26.34 g l − 1 L-lysine in a 5-l bioreactor. However, few reports are available regarding optimization strategies for submerged fermentation (SmF) to increase biomass or enhance enzyme activity of pesticide degrading microbes.…”
Microbial inoculant preparation is a prerequisite for its application in large-scale bioremediation. In the present study, sp. DC-6, an efficient acetochlor-degrading strain, was used to investigate the process of preparing the inoculant. Optimization of submerged fermentation (SmF) by response surface methodology (RSM) resulted in a first 22% increase in biomass of liquid inoculant. Then, a biomass increase of 2.18 times with 14.58% shortened incubation period was further obtained in optimized medium using a 7.5-l bioreactor. However, less than 0.4% viable cells in liquid inoculant survived after 180-days storage. Thus, optimized spray drying conditions were subsequently employed for the production of high viability powder (2.11 × 10 cfu g powder) without additive and its survival ratio (SR) after 180-days storage was still maintained at 90.5%. Both the 180-days stored powder and the original powder showed the same degradation performance, being able to completely degrade 200 mg l acetochlor within 48 h. This study demonstrated that strain DC-6 was suitable for industrial production of bacteria powder and provided a potential approach for the preparation of pesticide-degrading microbial inoculant.
“…Submerged culture is a key technology to obtain high yield liquid inoculant (Jafarzade et al 2013). Razak and Viswanath (2015) optimized the production of L-lysine using Corynebacterium glutamicum MH 20-22 B, which produced 26.34 g l − 1 L-lysine in a 5-l bioreactor. However, few reports are available regarding optimization strategies for submerged fermentation (SmF) to increase biomass or enhance enzyme activity of pesticide degrading microbes.…”
Microbial inoculant preparation is a prerequisite for its application in large-scale bioremediation. In the present study, sp. DC-6, an efficient acetochlor-degrading strain, was used to investigate the process of preparing the inoculant. Optimization of submerged fermentation (SmF) by response surface methodology (RSM) resulted in a first 22% increase in biomass of liquid inoculant. Then, a biomass increase of 2.18 times with 14.58% shortened incubation period was further obtained in optimized medium using a 7.5-l bioreactor. However, less than 0.4% viable cells in liquid inoculant survived after 180-days storage. Thus, optimized spray drying conditions were subsequently employed for the production of high viability powder (2.11 × 10 cfu g powder) without additive and its survival ratio (SR) after 180-days storage was still maintained at 90.5%. Both the 180-days stored powder and the original powder showed the same degradation performance, being able to completely degrade 200 mg l acetochlor within 48 h. This study demonstrated that strain DC-6 was suitable for industrial production of bacteria powder and provided a potential approach for the preparation of pesticide-degrading microbial inoculant.
“…In comparison with the conventional fermentations, the immobilization of microorganisms has many important advantages, such as higher cell density, reduced reaction time, long term reuse and higher product yield. For these reasons, immobilized cells have been used for various other valuable chemicals (Okay et al 2013 ; Razak and Viswanath 2015 ). Fig.…”
Indole acetic acid (IAA) is a plant growth-promoting hormone used in agriculture; therefore, its continuous production is of paramount importance. IAA-producing eight bacteria were isolated from the rhizosphere of Verbascum vulcanicum. Among them, Arthrobacter agilis A17 gave maximum IAA production (75 mg/L) and this strain was used to immobilization studies. The A. agilis A17 cells were immobilized in calcium alginate for the production of IAA. Optimization of process parameters for IAA production was carried out to enhance IAA production using immobilized cells. The maximal production of IAA was 520 mg/L under the following optimal conditions: 1% mannitol, 30 °C, pH 8.0, and 24 h incubation. It was determined that the immobilized cells could be reused (13 times) for the production of IAA.
“…Therefore, platform strains capable of producing OSH with high yield were successfully constructed. Further improvements in the production of OSH will be possible by employing the systems metabolic engineering approaches including system-wide flux optimization, CRISPRi-based screening, and fermentation optimization (Razak and Viswanath 2015;Shaikh et al 2016).…”
Section: Effects Of L-methionine Addition On Cell Growth and Osh Yielmentioning
-succinyl-l-homoserine (OSH) is a promising platform chemical for the production of C4 chemicals with huge market potential which can be produced by fermentation from glucose. To construct a strain capable of producing OSH with high yield, the (encodes transcriptional repressor) and (encodes a subunit of dl-methionine transporter) were deleted in W3110 to obtain a strain ∆JI. Then, overexpression of (encodes bifunctional aspartate kinase/homoserine dehydrogenase II) and inactivation of (encodes cystathionine γ-synthase) were implemented in one step, and the OSH titer of the resulting strain ∆JIB Trc was dramatically increased to 7.30 g/L. The feedback regulation was further relieved by progressively overexpressing (encodes homoserine-succinyltransferase), (encodes l-methionine exporter), and (encodes bifunctional aspartate kinase/homoserine dehydrogenase I) to increase the metabolic flux from aspartate to OSH. The 100% rationally designed strain ∆JIB Trc/pTrc- -Trc- - produced 9.31 g/L OSH from 20 g/L glucose (0.466 g/g glucose) in batch fermentation, which represents the highest OSH yield from glucose reported to date. The culture profiles of the newly constructed strains were recorded to investigate their productive properties. The effects of l-methionine addition on the fermentation process of the optimal strain were also studied. Our results demonstrate that tuning the expression level of , inactivation of, and attenuation of feedback resistance of the crucial enzymes in the biosynthetic pathway are the key factors that impact the OSH production in .
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