Recent Advances In Microbial Production Research Articles

Recent Advances in Microbial Production of Terpenoids from Biomass-derived Feedstocks

Recent Advances in Microbial Production of Terpenoids from Biomass-derived Feedstocks

Recent advances in microbial production of L-malic acid.

Over the last few decades, increasing concerns regarding fossil fuel depletion and excessive CO2 emissions have led to extensive fundamental studies and industrial trials regarding microbial chemical production. As an additive or precursor, L-malic acid has been shown to exhibit distinctive properties in the food, pharmaceutical, and daily chemical industries. L-malic acid is currently mainly fabricated through a fumarate hydratase-based biocatalytic conversion route, wherein petroleum-derived fumaric acid serves as a substrate. In this review, for the first time, we comprehensively describe the methods of malic acid strain transformation, raw material utilization, malic acid separation, etc., especially recent progress and remaining challenges for industrial applications. First, we summarize the various pathways involved in L-malic acid biosynthesis using different microorganisms. We also discuss several strain engineering strategies for improving the titer, yield, and productivity of L-malic acid. We illustrate the currently available alternatives for reducing production costs and the existing strategies for optimizing the fermentation process. Finally, we summarize the present challenges and future perspectives regarding the development of microbial L-malic acid production. KEY POINTS: • A range of wild-type, mutant, laboratory-evolved, and metabolically engineered strains which could produce L-malic acid were comprehensively described. • Alternative raw materials for reducing production costs and the existing strategies for optimizing the fermentation were sufficiently summarized. • The present challenges and future perspectives regarding the development of microbial L-malic acid production were elaboratively discussed.

A shortcut to carbon-neutral bioplastic production: Recent advances in microbial production of polyhydroxyalkanoates from C1 resources

Since the 20th century, plastics that are widely being used in general life and industries are causing enormous plastic waste problems since improperly discarded plastics barely degrade and decompose. Thus, the demand for polyhydroxyalkanoates (PHAs), biodegradable polymers with material properties similar to conventional petroleum-based plastics, has been increased so far. The microbial production of PHAs is an environment-friendly solution for the current plastic crisis, however, the carbon sources for the microbial PHA production is a crucial factor to be considered in terms of carbon-neutrality. One‑carbon (C1) resources, such as methane, carbon monoxide, and carbon dioxide, are greenhouse gases and are abundantly found in nature and industry. C1 resources as the carbon sources for PHA production have a completely closed carbon loop with much advances; i) fast carbon circulation with direct bioconversion process and ii) simple fermentation procedure without sterilization as non-preferable nutrients. This review discusses the biosynthesis of PHAs based on C1 resource utilization by wild-type and metabolically engineered microbial host strains via biorefinery processes.

Recent Advances in Microbial Production of Phloretin and Its Glycosides

Recent Advances in Microbial Production of Phloretin and Its Glycosides

Recent advances in microbial production of phenolic compounds

Phenolic compounds (PCs) are a group of compounds with various applications in nutraceutical, pharmaceutical and cosmetic industries. Their supply by plant extraction and chemical synthesis is often limited by low yield and high cost. Microbial production represents as a promising alternative for efficient and sustainable production of PCs. In this review, we summarize recent advances in this field, which include enzyme mining and engineering to construct artificial pathways, balance of enzyme expression to improve pathway efficiency, coculture engineering to alleviate metabolic burden and side-reactions, and the use of genetic circuits for dynamic regulation and high throughput screening. Finally, current challenges and future perspectives for efficient production of PCs are also discussed.

Bioprocess Optimization for the Production of Aromatic Compounds With Metabolically Engineered Hosts: Recent Developments and Future Challenges.

The most common route to produce aromatic chemicals – organic compounds containing at least one benzene ring in their structure – is chemical synthesis. These processes, usually starting from an extracted fossil oil molecule such as benzene, toluene, or xylene, are highly environmentally unfriendly due to the use of non-renewable raw materials, high energy consumption and the usual production of toxic by-products. An alternative way to produce aromatic compounds is extraction from plants. These extractions typically have a low yield and a high purification cost. This motivates the search for alternative platforms to produce aromatic compounds through low-cost and environmentally friendly processes. Microorganisms are able to synthesize aromatic amino acids through the shikimate pathway. The construction of microbial cell factories able to produce the desired molecule from renewable feedstock becomes a promising alternative. This review article focuses on the recent advances in microbial production of aromatic products, with a special emphasis on metabolic engineering strategies, as well as bioprocess optimization. The recent combination of these two techniques has resulted in the development of several alternative processes to produce phenylpropanoids, aromatic alcohols, phenolic aldehydes, and others. Chemical species that were unavailable for human consumption due to the high cost and/or high environmental impact of their production, have now become accessible.

Recent advances in microbial production of malic acid from renewable byproducts

In the last few years, ecofriendly malic acid production has received a potential platform for the bio-based chemicals to replace the dependency of fossil based resources. The main goal of this paper is to explore the feasibility of efficient production of malic acid from cost effective alternative renewable byproducts as feedstock. To replace the traditional method of malic acid production from petroleum-based compounds such as maleic acid, the efficiency of fermentation technology for malic acid production using various microorganisms has been improved. To date, glucose is designated as the best substrate for malic acid production. However, few reviews concerning about malic acid production by employing various microbial strains were reported. The current knowledge on the biosynthesis of malic acid has assisted to improve malic acid production using various microbial strains. But, there is still need for the continuous production and replacement of low-cost substrates to increase the yield of malic acid. This review provides an overview about progress, achievements, merits, challenges and future perspectives in malic acid production from cost effective alternative substrates. Thus, malic acid production can be economical using renewable byproducts like crude glycerol by employing appropriate microorganism.

Recent Advances in Microbial Production of Butanol as a Biofuel

In lieu of rising crude oil prices, exhaustion of petroleum feed stocks and environmental challenges, only renewable fuels have the potential to match the energy requirements of the future. Among the various renewable fuels, butanol has recently gained a lot of attention because of its advantages over other biofuels. Its microbial production by clostridia through ABE fermentation is being explored for improved yield and cost effectiveness. Using lignocellulosic wastes successfully for butanol production through ABE fermentation is a major breakthrough to deal with the future energy crisis. Genetic engineering of microbes to increase the carbon and redox balance, cell recycling, media optimization, mathematical modelling and tolerance improvement strategies are being attempted to overcome the hurdles of high production cost, by products formation leading to low yield and product toxicity. Along with genetic engineering major research is cantered on heterologous host engineering for improved butanol production and tolerance. This review highlights the recent advances in improving yield and tolerance to butanol in both Clostridial and heterologous hosts from genetic engineering and fermentation methodology aspects.
 Int. J. Appl. Sci. Biotechnol. Vol 7(2): 130-152

Recent advances in microbial production of mannitol: utilization of low-cost substrates, strain development and regulation strategies.

Mannitol has been widely used in fine chemicals, pharmaceutical industries, as well as functional foods due to its excellent characteristics, such as antioxidant protecting, regulation of osmotic pressure and non-metabolizable feature. Mannitol can be naturally produced by microorganisms. Compared with chemical manufacturing, microbial production of mannitol provides high yield and convenience in products separation; however the fermentative process has not been widely adopted yet. A major obstacle to microbial production of mannitol under industrial-scale lies in the low economical efficiency, owing to the high cost of fermentation medium, leakage of fructose, low mannitol productivity. In this review, recent advances in improving the economical efficiency of microbial production of mannitol were reviewed, including utilization of low-cost substrates, strain development for high mannitol yield and process regulation strategies for high productivity.

Recent advances in microbial production of aromatic natural products and their derivatives.

Aromatic natural products represent a diverse class of chemicals with great industrial significance. Usually, they serve as the building blocks for production of various polymers, esters, fibers, nutraceuticals, and pharmaceuticals. However, industrial synthesis of aromatic natural products still relies heavily on petroleum-based chemical processes, which are not sustainable and eco-friendly. In the past decades, construction of microbial cell factories that are able to efficiently convert renewable carbon sources into value-added products has made significant progress. This review highlights the recent advances in metabolic engineering efforts for biological production of aromatic natural products and their derivatives. Many novel pathways, enzymes, and products were reported in the literatures but have not yet detailed and informative viewed so far. Our goals are to provide a landscape of current works and present guidelines to address future challenges in biosynthesis of aromatic natural products and their derivatives using engineered microorganisms.