Scale translation from shaken to diffused bubble aerated systems for lycopene production by Blakeslea trispora under stimulated conditions

Advanced Fungal Biotechnologies in Accomplishing Sustainable Development Goals (SDGs): What Do We Know and What Comes Next?

The present era has witnessed an unprecedented scenario with extreme climate changes, depleting natural resources and rising global food demands and its widespread societal impact. From providing bio-based resources to fulfilling socio-economic necessities, tackling environmental challenges, and ecosystem restoration, microbes exist as integral members of the ecosystem and influence human lives. Microbes demonstrate remarkable potential to adapt and thrive in climatic variations and extreme niches and promote environmental sustainability. It is important to mention that advances in fungal biotechnologies have opened new avenues and significantly contributed to improving human lives through addressing socio-economic challenges. Microbe-based sustainable innovations would likely contribute to the United Nations sustainable development goals (SDGs) by providing affordable energy (use of agro-industrial waste by microbial conversions), reducing economic burdens/affordable living conditions (new opportunities by the creation of bio-based industries for a sustainable living), tackling climatic changes (use of sustainable alternative fuels for reducing carbon footprints), conserving marine life (production of microbe-based bioplastics for safer marine life) and poverty reduction (microbial products), among other microbe-mediated approaches. The article highlights the emerging trends and future directions into how fungal biotechnologies can provide feasible and sustainable solutions to achieve SDGs and address global issues.

Focus and Insights into the Synthetic Biology-Mediated Chassis of Economically Important Fungi for the Production of High-Value Metabolites

Substantial progress has been achieved and knowledge gaps addressed in synthetic biology-mediated engineering of biological organisms to produce high-value metabolites. Bio-based products from fungi are extensively explored in the present era, attributed to their emerging importance in the industrial sector, healthcare, and food applications. The edible group of fungi and multiple fungal strains defines attractive biological resources for high-value metabolites comprising food additives, pigments, dyes, industrial chemicals, and antibiotics, including other compounds. In this direction, synthetic biology-mediated genetic chassis of fungal strains to enhance/add value to novel chemical entities of biological origin is opening new avenues in fungal biotechnology. While substantial success has been achieved in the genetic manipulation of economically viable fungi (including Saccharomyces cerevisiae) in the production of metabolites of socio-economic relevance, knowledge gaps/obstacles in fungal biology and engineering need to be remedied for complete exploitation of valuable fungal strains. Herein, the thematic article discusses the novel attributes of bio-based products from fungi and the creation of high-value engineered fungal strains to promote yield, bio-functionality, and value-addition of the metabolites of socio-economic value. Efforts have been made to discuss the existing limitations in fungal chassis and how the advances in synthetic biology provide a plausible solution.

Carotenoids and Their Health Benefits as Derived via Their Interactions with Gut Microbiota

Carotenoids have been related to a number of health benefits. Their dietary intake and circulating levels have been associated with a reduced incidence of obesity, diabetes, certain types of cancer, and even lower total mortality. Their potential interaction with the gut microbiota (GM) has been generally overlooked but may be of relevance, as carotenoids largely bypass absorption in the small intestine and are passed on to the colon, where they appear to be in part degraded into unknown metabolites. These may include apo-carotenoids that may have biological effects because of higher aqueous solubility and higher electrophilicity that could better target transcription factors, i.e., NF-κB, PPARγ, and RAR/RXRs. If absorbed in the colon, they could have both local and systemic effects. Certain microbes that may be supplemented were also reported to produce carotenoids in the colon. Although some bactericidal aspects of carotenoids have been shown in vitro, a few studies have also demonstrated a prebiotic-like effect, resulting in bacterial shifts with health-associated properties. Also, stimulation of IgA could play a role in this respect. Carotenoids may further contribute to mucosal and gut barrier health, such as stabilizing tight junctions. This review highlights potential gut-related health-beneficial effects of carotenoids and emphasizes the current research gaps regarding carotenoid-GM interactions.

Lycopene as a Potential Bioactive Compound: Chemistry, Extraction, and Anticancer Prospective

Lycopene, a potential bioactive agent, is a non-pro-vitamin A carotenoid recognized as a potent antioxidant. It is extracted from plants like tomatoes, watermelons, red carrots and papayas and has remarkable health benefits. A significant amount of research has been assisted to date to establish the anticancer activity of lycopene. Our review enhances information about the promising anticancer potential of this compound. The biological activity of lycopene has been described in several studies in regard to pancreatic, breast, prostate, liver, gastric, ovarian, kidney, skin, intestine, brain and spinal cord cancers. Lycopene resists cancer by inhibition of apoptosis, induction of cell proliferation, cell invasion, cell cycle development, metastasis and angiogenesis. The mechanisms of anticancer action of lycopene are attributed to the management of certain signal transduction pathways, such as modulation of insulin-like growth factors system, PI3K/Akt pathway, modification of important gene expression, inhibit the activity of sex steroid hormones, and the conversation of mitochondrial behavior. Hence, this review focuses on current knowledge of sources, extraction techniques, and chemistry of lycopene, as well as the prospective mechanisms of action related with its anticancer activity. Also, it summarizes the background information about lycopene and the most current research with consideration to its aspect in treating several types of cancer together with future directions.

Protoplast fusion between Blakeslea trispora 14,271 (+) and 14,272 (-) enhanced the yield of lycopene and β-carotene

Blakeslea trispora, a heterothallic Zygomycota with two mating types (termed "plus" and "minus"), is an ideal source of lycopene and β-carotene. The lycopene and β-carotene yields when the two type strains are used for fermentation separately are lower than those when they are joint together. To enhance the yield of lycopene and β-carotene in B. trispora, protoplast fusion technology was carried out between ATCC 14,271 (+) and ATCC 14,272 (-). After protoplast preparation, protoplast fusion, fusion sorting, fusion regeneration, and high-throughput screening, two fusions (Fu-1and Fu-2) with high lycopene and β-carotene yields were obtained. The lycopene yields of Fu-1 and Fu-2 were increased to 0.60 mg/gDW and 0.90 mg/gDW, which were respectively 3.62- and 5.44-fold those of 14,271 and 1.76- and 2.64-fold those of 14,272. The β-carotene yields of Fu-1 and Fu-2 were increased to 22.07 mg/gDW and 36.93 mg/gDW, which were respectively 1.72- and 2.89-fold those of 14,271 and 1.23- and 2.06-fold those of 14,272. In this study, the protoplast fusion technique was successfully used in Blakeslea trispora, providing new ideas for improving lycopene and β-carotene production.

Metabolic Engineering of Different Microbial Hosts for Lycopene Production

As a result of the extensive use of lycopene in a variety of fields, especially the dietary supplement and health food industries, the production of lycopene has attracted considerable interest. Lycopene can be obtained through extraction from vegetables and chemical synthesis. Alternatively, the microbial production of lycopene has been extensively researched in recent years. Various types of microbial hosts have been evaluated for their potential to accumulate a high level of lycopene. Metabolic engineering of the hosts and optimization of culture conditions are performed to enhance lycopene production. After years of research, great progress has been made in lycopene production. In this review, strategies used to improve lycopene production in different microbial hosts and the advantages and disadvantages of each microbial host are summarized. In addition, future perspectives of lycopene production in different microbial hosts are discussed.

Biotechnological production of lycopene by microorganisms

Lycopene is a dark red carotenoid belonging to C40 terpenoids and is widely found in a variety of plants, especially ripe red fruits and vegetables. Lycopene has been shown to reduce the risk of prostate cancer, other cancers, and cardiovascular disease. It is one of the most widely used carotenoids in the healthcare product market. Currently, commercially available lycopene is mainly extracted from tomatoes. However, production of lycopene from plants is costly and environmentally unfriendly. To date, there have been many reports on the biosynthesis of lycopene by microorganisms, providing another route for lycopene production. This review discusses the lycopene biosynthetic pathway and natural and engineered lycopene-accumulating microorganisms, as well as their production of lycopene. The effects of different metabolic engineering strategies on lycopene accumulation are also considered. Furthermore, this work presents perspectives concerning the microbial production of lycopene, especially trends to construct microbial cell factories for lycopene production. KEY POINTS: • Recent achievements in the lycopene biosynthesis in microorganisms. • Review of lycopene biosynthetic metabolism engineering strategy. • Discuss the current challenges and prospects of using microorganisms to produce lycopene.

Engineered Microbes for Pigment Production Using Waste Biomass

Agri-food waste biomass is the most abundant organic waste and has high valorisation potential for sustainable bioproducts development. These wastes are not only recyclable in nature but are also rich sources of bioactive carbohydrates, peptides, pigments, polyphenols, vitamins, natural antioxidants, etc. Bioconversion of agri-food waste to value-added products is very important towards zero waste and circular economy concepts. To reduce the environmental burden, food researchers are seeking strategies to utilize this waste for microbial pigments production and further biotechnological exploitation in functional foods or value-added products. Microbes are valuable sources for a range of bioactive molecules, including microbial pigments production through fermentation and/or utilisation of waste. Here, we have reviewed some of the recent advancements made in important bioengineering technologies to develop engineered microbial systems for enhanced pigments production using agri-food wastes biomass/by-products as substrates in a sustainable way.

Design and tailoring of an artificial DNA scaffolding system for efficient lycopene synthesis using zinc-finger-guided assembly

A highly efficient lycopene production system was constructed by assembling enzymes fused to zinc-finger motifs on DNA scaffolds in vitro and in vivo. Three key enzymes of the lycopene synthesis pathway, geranylgeranyl diphosphate synthase, phytoene synthase, and phytoene desaturase, were fused with zinc-finger proteins, expressed and purified. Recombinant plasmids of the pS series containing DNA scaffolds that the zinc-finger proteins can specifically bind to were constructed. In the in vitro system, the production efficiency of lycopene was improved greatly after the addition of the scaffold plasmid pS231. Subsequently, the plasmid pET-AEBI was constructed and introduced into recombinant Escherichia coli BL21 (DE3) for expression, together with plasmids of the pS series. The lycopene production rate and content of the recombinant strain pp231 were higher than that of all strains carrying the DNA scaffold and the control. With the addition of cofactors and substrates in the lycopene biosynthesis pathway, the lycopene yield of pp231 reached 632.49 mg/L at 40 h, representing a 4.7-fold increase compared to the original recombinant strain pA1A3. This DNA scaffold system can be used as a platform for the construction and production of many biochemicals synthesized via multi-enzyme cascade reactions.

Effects of exogenous lipids and cold acclimation on lycopene production and fatty acid composition in Blakeslea trispora

Exogenous lipids serving as stimulators to improve lycopene production in Blakeslea trispora have been widely reported. However, the selection basis of exogenous lipids and their effects on intracellular lipids are not very clear. In this study, five plant oils with different fatty acid compositions were selected to investigate their effects on lycopene production, fatty acid composition and the desaturation degree of intracellular lipids. Among the oils, soybean oil, with a fatty acid composition similar to that of mycelium, exhibited the best stimulating effect on lycopene formation (improvement of 82.1%). The plant oils enhanced the total content of intracellular lipids and the desaturation degree of reserve lipids due to the alteration of fatty acid composition, especially in neutral lipids. Lycopene production was increased with the improved desaturation degree of intracellular lipids, which may be attributed to the enhancement of storage capacity for lycopene in storage lipid, thus reducing the feedback regulation of free lycopene. In addition, the increase of the desaturation degree of reserve lipids through temperature-changing fermentation also enhanced lycopene production. The present study could serve as a basis for a better understanding of the relationship between the fatty acid composition of reserve lipids and lycopene production.

Challenges and tackles in metabolic engineering for microbial production of carotenoids

Naturally occurring carotenoids have been isolated and used as colorants, antioxidants, nutrients, etc. in many fields. There is an ever-growing demand for carotenoids production. To comfort this, microbial production of carotenoids is an attractive alternative to current extraction from natural sources. This review summarizes the biosynthetic pathway of carotenoids and progresses in metabolic engineering of various microorganisms for carotenoid production. The advances in synthetic pathway and systems biology lead to many versatile engineering tools available to manipulate microorganisms. In this context, challenges and possible directions are also discussed to provide an insight of microbial engineering for improved production of carotenoids in the future.

CRISPR/Cas9-based genome editing of the filamentous fungi: the state of the art

In recent years, a variety of genetic tools have been developed and applied to various filamentous fungi, which are widely applied in agriculture and the food industry. However, the low efficiency of gene targeting has for many years hampered studies on functional genomics in this important group of microorganisms. The emergence of CRISPR/Cas9 genome-editing technology has sparked a revolution in genetic research due to its high efficiency, versatility, and easy operation and opened the door for the discovery and exploitation of many new natural products. Although the application of the CRISPR/Cas9 system in filamentous fungi is still in its infancy compared to its common use in E. coli, yeasts, and mammals, the deep development of this system will certainly drive the exploitation of fungal diversity. In this review, we summarize the research progress on CRISPR/Cas9 systems in filamentous fungi and finally highlight further prospects in this area.