Photosynthesis, as an efficient pathway for solar energy capture and utilization, has supported aerobionts for billions of years. The imitation of photosynthesis to construct artificial photo-enzymatic-coupling catalysis system has become a powerful means to solve energy and environmental problems. After years of in-depth research on this coupled system, through ingenious and rational design, the synergistic effect of photo- and enzymatic catalyses has played a significant role in many different fields, including solar-driven fuel production, chiral chemical synthesis and carbon dioxide fixation. Furthermore, light in enzymatic catalysis could also endow enzyme new possibilities. Photo-induced radical cofactor could bring catalytic promiscuity to enzymes, making them catalyze reactions that natural enzymes cannot. This review summarizes the advances in photo-enzymatic-coupling catalysis system and introduces its essential components, their integration and application. The possibilities presented by photo-induced catalytic promiscuity and its significance for expanding the toolbox of enzymes are also discussed.
The domain of industrial biomanufacturing is enthusiastically embracing the concept of Digital Twin, owing to its promises of increased process efficiency and resource utilisation. However, Digital Twin in biomanufacturing is not yet clearly defined and this sector of the industry is falling behind the others in terms of its implementation. On the other hand, some of the benefits of Digital Twin seem to overlap with the more established practices of process control and optimization, and the term is vaguely used in different scenarios. In an attempt to clarify this issue, we investigate this overlap for the specific case of fermentation operation, a central step in many biomanufacturing processes. Based on this investigation, a framework built upon a five-step pathway starting from a basic steady-state process model is proposed to develop a fully-fledged Digital Twin. For demonstration purposes, the framework is applied to a bench-scale second-generation ethanol fermentation process as a case study. It is proposed that the success or failure of a fully-fledged Digital Twin implementation is determined by key factors that comprise the role of modelling, human operator actions, and other propositions of economic value.
The asymmetric hydroxylation of inactive carbon atoms in organic compounds remains an important reaction in the industrial synthesis of valuable chiral compounds. Fe(II) and 2-ketoglutarate-dependent dioxygenases (Fe/2-kg DOs) are the largest known subgroups of mononuclear nonheme-Fe(II)-dependent oxygenases, catalyzing various oxidation reactions of C–H bonds. Recent developments in Fe/2-kg DO-related researches have coupled concepts from bioinformatics, synthetic biology, and computational biology to establish effective biotransformation systems. The most well-studied and characterized activity of the Fe/2-kg DOs is substrate hydroxylation, with regard to which mechanistic studies involving the Fe center assist in engineering the protein frameworks of these enzymes to obtain the desired catalytic enhancements. Amino acids are typical substrates of Fe/2-kg DOs and are usually converted into hydroxyl amino acids, which are widely used as intermediates in pharmaceutical and fine chemical industries. Herein, we have reviewed prior structural and mechanistic studies on Fe/2-kg DOs, as well as studies on the Fe/2-kg DO-mediated selective C–H oxidation process for selective hydroxyl amino acid synthesis, which will further our journey along the promising path of building complexity via C–H bond oxidation. Further, new bioinformatics techniques should be adopted with structure-based protein rational design to mine sequence databases and shrink mutant libraries to produce a diverse panel of functional Fe/2-kg DOs capable of catalyzing targeted reactions.
Lacto-N-neotetraose (LNnT), one of the most important human milk oligosaccharides, can be used as infants’ food additives. Nowadays, extraction, chemical and biological synthesis were utilized to obtain LNnT, while these methods still face some problems such as low yield and high cost. The aim of current work is to construct a de novo biosynthesis pathway of LNnT in E. coli K12 MG1655. The lgtA and lgtB were first expressed by a plasmid, resulting in a LNnT titer of 0.04 g/L. To improve the yield of LNnT on substrate lactose, lacZ and lacI were knocked out, and lacY was over-expressed. As a result, the yield of LNnT on lactose increased from 0.01 to 0.09 mol/mol, and the titer of LNnT elevated to 0.41 g/L. In addition, the pathway was regulated using the titer of Lacto-N-triose II (LNTII) as a measure, and obtained a high titer strain of LNnT for 1.04 g/L. Finally, the gene expressions were fine-tuned, the titer of LNnT reached 1.2 g/L, which was 93% higher than the control strain, and the yield on lactose reached 0.28 mol/mol. The engineering strategy of pathway construction and modulation used in this study is applicable to facilitate the microbial production of other metabolites in E. coli.
Apple pomace is a rich source of dietary fiber that can be easily incorporated in bakery products to enhance the nutritional quality of the product. In the present study, apple pomace powder was utilized for formulating fiber-enriched muffin pre-mix. Apple pomace powder (APP) was supplemented in refined wheat flour at different concentration and 33% was found highly acceptable by the sensory panelists on a 9 point hedonic scale. Samples were analyzed for proximate composition, functional properties (water holding, swelling, foaming and emulsion), phenolic content and calorific value. Storage study of polyethylene and aluminium laminate pouch (ALP) packed fiber-enriched muffin pre-mix was also conducted for six months at ambient conditions. Cost evaluation showed that the cost of APP-based pre-mix was comparable to conventional wheat-based pre-mix. Results of this study support the possibility of producing high-fiber muffin pre-mix with desirable quality and quantity in a sustainable manner.
Oxidation destroys the flavor and freshness of the beer, and yeast with improved antioxidant activity would benefit the flavor stability of the beer. The aim of this work was to study the antioxidant networks of lager yeast for brewing industry. Through transcriptome and metabolome analysis, we were able to map changes in anti-oxidant pathways and transcription of genes in lager yeast. Results suggested that metabolic energy variation in yeast might be the main reason for the improved anti-oxidant capacity. Lower metabolic rate kept the yeast at relatively lower respiratory status at the end of fermentation, thereby prolonging the lifespan and potentially supporting its usage in serial fermentations. Up-regulation of mannose synthesis and hexose transport strengthened the cell structure, which may have contributed to the anti-oxidant capacity of yeast. A deeper understanding of the globally regulation pattern of anti-oxidation in lager yeast is expected to support the design of strain development strategies for improved anti-oxidant capacity of yeast for fermentation industry.
Prodigiosin is a secondary metabolite mainly produced at 30 °C in Serratia marcescens, but it can hardly be synthetized at 37 °C or higher. In this study, we provide insight into the metabolic regulation of prodigiosin synthesis in response to temperature through transcriptome sequencing. The analysis of the function of differentially expressed genes suggested that temperature resulted in significant alteration of the metabolic pathways between 30 and 37 °C. Specifically, 30 °C favored transcriptional expression of the pig gene cluster. At the same time, the carbon flux was redistributed to pathways of pyruvate, proline, serine, especially homoserine, cystathionine, homocysteine, methionine, and s-adenosylmethionine metabolism, all involved in prodigiosin biosynthesis, and was finally increased towards the prodigiosin synthesis pathway in S. marcescens at 30 °C. Interestingly, results further confirmed increased transcriptional level of five regulators (LuxS, RpoS, Hfq, EepR, CRP), and decreased content of hexS through qPCR. Finally, successful co-overexpression of mmuM and metK, related to homocysteine, methionine, and s-adenosylmethionine metabolism, in the chromosome of JNB5-1 (JNB5-1/MK) resulted in increased prodigiosin titer up to 7.57 g/L in JNB5-1/MK at 30 °C, which was 41.2% higher than that in JNB5-1. Our transcriptome analysis provides further insight into the strain's response to temperature changes at the transcription level, which is of great significance for improving the production of prodigiosin.
The aim of this study was to use dried corn silk powder variety of VL Baby corn-1 for formulation of flavoured herbal tea with different combination of Thyme (Trachyspermum ammi), Clove (Syzygium aromaticum), Cinnamon powder (Cinnamomum verum), Timur (Zanthoxylum alatum), Tulsi (Holy basil) (Ocimum tenuiflorum), Gandraini (Achillea millefolium), Lemon grass (Cymbopogon citratus), Blend (Clove + Timur + Gandraini), and one only corn silk without any other herbs and to know antioxidant properties of developed tea. Result of sensory evaluation experiment showed that all combinations were liked moderately. Lemon grass flavour followed by cinnamon and clove blend obtained highest score. Total phenolic content, total flavonoid content, DPPH free radical scavenging activity and total antioxidant activity for all flavour are analyzed and reported. Results on DPPH free radical scavenging activity indicated that corn silk tea had 81.215 ± 0.75 µg/mL whereas blend with Timur had significant highest value and Thyme blend had lowest value 64.20 ± 0.40 among all eight different blends with corn silk. The values for total antioxidant capacity blends with Timur (Zanthoxylum alatu) in corn silk showed significantly (P < 0.05) highest value and Clove, Timur, Gandraini blends got lowest value.
In the present study, municipal secondary sludge and purified glycerol (obtained after acid treatment of crude glycerol) were used together for lipid production using intermittent feeding strategy. Intermittent sludge feeding strategy (sludge SS 30 g/L) resulted in a higher biomass (54.99 g/L) and lipid concentration (25.35 g/L) at 96 h when compared to 35 g/L SS single sludge feeding or control strategy (45.67 g/L biomass & 19.16 g/L lipid). Moreover, the intermittent sludge feeding strategy significantly reduced foaming and requirement of anti-foam during fermentation when compared to control strategy. The energy balance of biodiesel production from lipid obtained by intermittent sludge feeding strategy (30 g/L SS) was energetically favorable. It was also revealed from yield coefficients and energy balance that sludge had an important contribution in microbial lipid and biodiesel production.
The pigments are vital parts of photosynthetic machinery in algae and exhibit a myriad of applications as nutraceuticals, cosmetics, colorants, which find huge applications in many industires, including the paint industry and paper industry. The antimicrobial, antioxidative, anti-inflammatory, and anti-cancer potential of microalgal pigments contribute towards their varied industrial applications. In this study, pigments (Fucoxanthin, C-phycocyanin, and C-phycoerythrin), extracted from microalgae were investigated to check the antimicrobial efficacy using agar well diffusion and disc diffusion methods against pathogenic bacteria: Staphylococcus aureus and Escherichia coli. The fucoxanthin pigment isolated from diatom Thalassiosira sp. exhibited the highest antibacterial activity against Staphylococcus aureus (17 ± 1.53 mm) and in contrast fucoxanthin pigment isolated from Chaetoceroes sp. exhibited the highest bactericidal activity against Escherichia coli (18 ± 1). The pigment extract of Spirulina plantesis showed the highest antibacterial activity against E. coli (41 ± 0.3) and S. elongatus also exhibited high antibacterial activity against E. coli (32 ± 0.5) while Anabaena variabilis showed the highest antibacterial activity against Staphylococcus aureus (34 ± 0.5). The potential of microalgal pigments is highly valuable and further extensive studies can elaborate the underlying mechanisms.