The Role of Microbes in Biorefinery Products and Biofuels

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Microbial Biotechnology".

Deadline for manuscript submissions: 31 May 2024 | Viewed by 5447

Special Issue Editor


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Guest Editor
Biorefinery Industry Development Facility (BIDF), Council for Scientific and Industrial Research (CSIR), Durban, South Africa
Interests: Microbial processing; biorefineries; circular bioeconomy

Special Issue Information

Dear Colleagues,

Resource depletion, food insecurity, energy shortages, greenhouse gas emissions, and ecological deterioration are among the critical issues that are under the United Nations’ Sustainable Agenda. For this reason, the global community is expected to promptly respond to these anthropogenic crises by making a transition to carbon-neutral technologies. In recent years, different stakeholders including scientists, industries, and policymakers have shown keen interest in the attainment of the UN’s goals.

Microbial biorefineries are gaining increasing prominence owing to their ability to produce a broad spectrum of high-value-added products such as biofuels, biochemicals, biomaterials, and bioactive compounds using diverse carbon sources including organic wastes. From an economic and environmental standpoint, microbial-driven processes are advantageous as they can unlock value from biowastes using affordable and accessible microbial cell factories as biocatalysts. In addition, these bioprocesses are desirable because they are embedded in the circular bioeconomy, particularly their role in environmental remediation strategies, and could save industries, governments, and taxpayers millions of dollars earmarked for treating organic waste streams and landfill sites. Against this background, this Special Issue invites scientists specializing in the cultivation, engineering, and/or application of microorganisms to share their knowledge, with a collective objective to (i) outline the state of the art on the role of microbes in biorefinery products and biofuels, (ii) shed light on the recent advances in various microbial biorefinery-based processes, and (iii) provide the technological gaps that need to be addressed in order to accelerate the advancement of this research field. Original articles and reviews papers discussing the role of microbes in biorefinery products and biofuels (and other related topics) are all welcomed in this Special Issue.

Dr. Patrick Sekoai
Guest Editor

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Keywords

  • biofuels
  • biochemicals
  • bioactives
  • circular bioeconomy
  • fermentation
  • anaerobic digestion
  • bioprocessing
  • biotechnology
  • waste valorization
  • sustainability

Published Papers (2 papers)

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Research

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12 pages, 1674 KiB  
Article
Engineering Terpene Production Pathways in Methylobacterium extorquens AM1
by Allison Hurt, Jacob D. Bibik, Norma Cecilia Martinez-Gomez and Björn Hamberger
Microorganisms 2024, 12(3), 500; https://doi.org/10.3390/microorganisms12030500 - 29 Feb 2024
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Abstract
Terpenes are diverse specialized metabolites naturally found within plants and have important roles in inter-species communication, adaptation and interaction with the environment. Their industrial applications span a broad range, including fragrances, flavors, cosmetics, natural colorants to agrochemicals and therapeutics, yet formal chemical synthesis [...] Read more.
Terpenes are diverse specialized metabolites naturally found within plants and have important roles in inter-species communication, adaptation and interaction with the environment. Their industrial applications span a broad range, including fragrances, flavors, cosmetics, natural colorants to agrochemicals and therapeutics, yet formal chemical synthesis is economically challenging due to structural complexities. Engineering terpene biosynthesis could represent an alternative in microbial biotechnological workhorses, such as Saccharomyces cerevisiae or Escherichi coli, utilizing sugars or complex media as feedstocks. Host species that metabolize renewable and affordable carbon sources may offer unique sustainable biotechnological alternatives. Methylotrophs are bacteria with the capacity to utilize one-carbon feedstocks, such as methanol or formate. They colonize the phyllosphere (above-ground area) of plants, and many accumulate abundant carotenoid pigments. Methylotrophs have the capacity to take up and use a subset of the rare earth elements known as lanthanides. These metals can enhance one-carbon (methylotrophic) metabolism. Here, we investigated whether manipulating the metabolism enables and enhances terpene production. A carotenoid-deficient mutant potentially liberates carbon, which may contribute to bioproduct accumulation. To test this hypothesis, terpene-producing bacterial strains regulated by two distinct promoters were generated. Wildtype Methylobacterium extorquens, ∆Meta1_3665, a methylotrophic mutant lacking the carotenoid pathway, and an E. coli strain were transformed with an exogenous terpene pathway and grown both in the presence and absence of lanthanides. The extraction, and the comparison of analytical profiles, provided evidence that engineered cultured M. extorquens under control of a native, inducible methylotrophic promoter can yield the sesquiterpene patchoulol when supplemented with lanthanide. In contrast, using a moderate-strength constitutive promoter failed to give production. We demonstrated colonization of the phyllosphere with the engineered strains, supporting the future engineering of selected species of the plant microbiome and with promising implications for the synthetic biology of small molecules. Full article
(This article belongs to the Special Issue The Role of Microbes in Biorefinery Products and Biofuels)
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Review

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22 pages, 1998 KiB  
Review
Valorization of Food Waste into Single-Cell Protein: An Innovative Technological Strategy for Sustainable Protein Production
by Patrick T. Sekoai, Yrielle Roets-Dlamini, Frances O’Brien, Santosh Ramchuran and Viren Chunilall
Microorganisms 2024, 12(1), 166; https://doi.org/10.3390/microorganisms12010166 - 13 Jan 2024
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Abstract
The rapidly increasing population and climate change pose a great threat to our current food systems. Moreover, the high usage of animal-based and plant-based protein has its drawbacks, as these nutritional sources require many hectares of land and water, are affected by seasonal [...] Read more.
The rapidly increasing population and climate change pose a great threat to our current food systems. Moreover, the high usage of animal-based and plant-based protein has its drawbacks, as these nutritional sources require many hectares of land and water, are affected by seasonal variations, are costly, and contribute to environmental pollution. Single-cell proteins (SCPs) are gaining a lot of research interest due to their remarkable properties, such as their high protein content that is comparable with other protein sources; low requirements for land and water; low carbon footprint; and short production period. This review explores the use of food waste as a sustainable feedstock for the advancement of SCP processes. It discusses SCP studies that exploit food waste as a substrate, alongside the biocatalysts (bacteria, fungi, yeast, and microalgae) that are used. The operational setpoint conditions governing SCP yields and SCP fermentation routes are elucidated as well. This review also demonstrates how the biorefinery concept is implemented in the literature to improve the economic potential of “waste-to-protein” innovations, as this leads to the establishment of multiproduct value chains. A short section that discusses the South African SCP scenario is also included. The technical and economic hurdles facing second-generation SCP processes are also discussed, together with future perspectives. Therefore, SCP technologies could play a crucial role in the acceleration of a “sustainable protein market”, and in tackling the global hunger crisis. Full article
(This article belongs to the Special Issue The Role of Microbes in Biorefinery Products and Biofuels)
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