Microbioreactors for nutrient‐controlled microbial cultures: Bridging the gap between bioprocess development and industrial use

This study first employed a combined pretreatment of low‐dose peroxy‐disulfate (PDS) and initial pH 10 to promote short‐chain fatty acids (SCFAs) production via acidogenic fermentation using different types of sewage sludge as substrates. The experimental results showed that the yield of maximal SCFAs and acetate proportion after the combined pretreatment were 1513.82 ± 28.25 mg chemical oxygen demand (COD)/L and 53.64%, and promoted by 1.28 and 1.56 times higher, respectively, compared to the sole initial pH 10 pretreatment. Furthermore, in terms of the disintegration degree of sewage sludge, it increased by more than 18% with the combined pretreatment compared to the pretreatment of sole initial pH 10. Waste‐activated sludge (WAS) from A2/O and Bardenpho processes were more biodegradable, explained by the 1.47‐ and 1.35‐times higher disintegration rate than those from oxidation ditch and they favored acetate dominant fermentation. Correlation analysis revealed a strong correlation (p ≤ 0.01) between SCFAs production and soluble COD, total proteins, proteins in soluble‐extracellular polymeric substances (SEPS), total polysaccharides, and polysaccharides in SEPS. Mechanism explorations showed that preoxidation with PDS enhanced the solubilization and biodegradability of complex substrates, and altered the microbial community structure during the fermentation process. Firmicutes and Tetrasphaera were proven to play a key role in improving SCFA production, especially in promoting acetate production by converting additional SCFAs into acetate. Additionally, the addition of PDS greatly promoted sulfur and iron‐related metabolic activities. Finally, the combined pretreatment was estimated to be a cost‐effective solution for reutilizing and treating Fe‐sludge.

Section: Analysis Of Microbial Community Shiftsmentioning

confidence: 99%

Enhancing short‐chain fatty acids production via acidogenic fermentation of municipal sewage sludge: Effect of sludge characteristics and peroxydisulfate pre‐oxidation

Liu,

Cheng,

et al. 2024

“…To fulfill the requirements of the industrial sector, it often necessitates a series of successive rounds involving random mutagenesis and screening, followed by subsequent refinements in the cultivation procedures for optimal results. [4] While various instances have showcased the effectiveness of mutagenesis and screening methods, the underlying mechanisms through which industrial actinobacteria augment yields or synthesize desired metabolites largely remain enigmatic. [5] Erythromycin, a prominent constituent of the macrolide antibiotic class, has been established as a vital therapeutic agent for addressing diverse infections attributed to Gram-positive bacteria.…”

Section: Introductionmentioning

confidence: 99%

Enhancing erythromycin production in Saccharopolyspora erythraea through rational engineering and fermentation refinement: A Design‐Build‐Test‐Learn approach

Shao,

Xu,

et al. 2024

Industrial production of bioactive compounds from actinobacteria, such as erythromycin and its derivatives, faces challenges in achieving optimal yields. To this end, the Design‐Build‐Test‐Learn (DBTL) framework, a systematic metabolic engineering approach, was employed to enhance erythromycin production in Saccharopolyspora erythraea (S. erythraea) E3 strain. A genetically modified strain, S. erythraea E3‐CymRP21‐dcas9‐sucC (S. erythraea CS), was developed by suppressing the sucC gene using an inducible promoter and dcas9 protein. The strain exhibited improved erythromycin synthesis, attributed to enhanced precursor synthesis and increased NADPH availability. Transcriptomic and metabolomic analyses revealed altered central carbon metabolism, amino acid metabolism, energy metabolism, and co‐factor/vitamin metabolism in CS. Augmented amino acid metabolism led to nitrogen depletion, potentially causing cellular autolysis during later fermentation stages. By refining the fermentation process through ammonium sulfate supplementation, erythromycin yield reached 1125.66 mg L−1, a 43.5% increase. The results demonstrate the power of the DBTL methodology in optimizing erythromycin production, shedding light on its potential for revolutionizing antibiotic manufacturing in response to the global challenge of antibiotic resistance.

“…This allows to control microbial growth by adjusting the substrate influx. [21,22] ○ Extended batch cultivation, on the other hand, prolongs the fermentation process beyond the point where microorganisms would typically enter the stationary phase. This is achieved by continuously adding nutrients, allowing the microorganisms to grow and produce the target product for an extended duration, leading to increased overall yields.…”

Section: Introductionmentioning

confidence: 99%

Feeding strategies for Sporosarcina pasteurii cultivation unlock more efficient production of ureolytic biomass for MICP

Lapierre,

Huber

2024

The bacterium Sporosarcina pasteurii is the most commonly used microorganism for Microbial Induced Calcite Precipitation (MICP) due to its high urease activity. To date, no proper fed‐batch cultivation protocol for S. pasteurii has been published, even though this cultivation method has a high potential for reducing costs of producing microbial ureolytic biomass. This study focusses on fed‐batch cultivation of S. pasteurii DSM33. The study distinguishes between limited fed‐batch cultivation and extended batch cultivation. Simply feeding glucose to a S. pasteurii culture does not seem beneficial. However, it was exploited that S. pasteurii is auxotrophic for two vitamins and amino acids. Limited fed‐batch cultivation was accomplished by feeding the necessary vitamins or amino acids to a culture lacking them. Feeding nicotinic acid to a nicotinic acid deprived culture resulted in a 24% increase of the specific urease activity compared to a fed culture without nicotinic acid limitation. Also, extended batch cultivation was explored. Feeding a mixture of glucose and yeast extract results in OD600 of ≈70 at the end of cultivation, which is the highest value published in literature so far. These results have the potential to make MICP applications economically viable.