Microbial Biotechnology最新文献

Recently, there has been growing interest in biopreparations that intensify the decomposition of crop residues. These preparations can promote nutrient cycling and soil fertility, ultimately supporting healthy plant growth and increasing agricultural productivity. However, the development and commercialization of biopreparations poses unique challenges. Producers of biopreparations struggle to develop highly effective preparations, which then face regulatory hurdles and must win market acceptance. This literature review provides up-to-date data on microbial preparations available commercially on the European market, along with information on current relevant regulations. Challenges for the development and commercialization of new biopreparations are also discussed. The development and commercialization of biopreparations require a comprehensive approach that addresses the complex interplay of microbial and environmental factors. The need for more specific regulations on biopreparations for decomposing crop residues, clearer instructions on their use, and further research on the overall impact of biopreparations on the soil metabolome and optimal conditions for their application were indicated. Moreover, manufacturers should prioritize the development of high-quality products that meet the needs of farmers and address concerns about environmental impact and public acceptance.

Cyanobacteria are important targets for biotechnological applications due to their ability to grow in a wide variety of environments, rapid growth rates, and tractable genetic systems. They and their bioproducts can be used as bioplastics, biofertilizers, and in carbon capture and produce important secondary metabolites that can be used as pharmaceuticals. However, the photosynthetic process in cyanobacteria can be limited by a wide variety of environmental factors such as light intensity and wavelength, exposure to UV light, nutrient limitation, temperature, and salinity. Carefully considering these limitations, modifying the environment, and/or selecting cyanobacterial species will allow cyanobacteria to be used in biotechnological applications.

The human gut microbiota influences its host via multiple molecular pathways, including immune system interactions, the provision of nutrients and regulation of host physiology. Dietary fibre plays a crucial role in maintaining a healthy microbiota as its primary nutrient and energy source. Industrialisation has led to a massive decrease of habitual fibre intake in recent times, and fibre intakes across the world are below the national recommendations. This goes hand in hand with other factors in industrialised societies that may negatively affect the gut microbiota, such as medication and increased hygiene. Non-communicable diseases are on the rise in urbanised societies and the optimisation of dietary fibre intake can help to improve global health and prevent disease. Early life interventions shape the developing microbiota to counteract malnutrition, both in the context of industrialised nations with an overabundance of cheap, highly processed foods, as well as in Low- and Middle-Income Countries (LMICs). Adequate fibre intake should, however, be maintained across the life course to promote health. Here we will discuss the current state of dietary fibre research in the global context and consider different intervention approaches.

Arguably, the greatest threat to bacteria is phages. It is often assumed that those bacteria that escape phage infection have mutated or utilized phage-defence systems; however, another possibility is that a subpopulation forms the dormant persister state in a manner similar to that demonstrated for bacterial cells undergoing nutritive, oxidative, and antibiotic stress. Persister cells do not undergo mutation and survive lethal conditions by ceasing growth transiently. Slower growth and dormancy play a key physiological role as they allow host phage defence systems more time to clear the phage infection. Here, we investigated how bacteria survive lytic phage infection by isolating surviving cells from the plaques of T2, T4, and lambda (cI mutant) virulent phages and sequencing their genomes. We found that bacteria in plaques can escape phage attack both by mutation (i.e. become resistant) and without mutation (i.e. become persistent). Specifically, whereas T4-resistant and lambda-resistant bacteria with over a 100,000-fold less sensitivity were isolated from plaques with obvious genetic mutations (e.g. causing mucoidy), cells were also found after T2 infection that undergo no significant mutation, retain wild-type phage sensitivity, and survive lethal doses of antibiotics. Corroborating this, adding T2 phage to persister cells resulted in 137,000-fold more survival compared to that of addition to exponentially growing cells. Furthermore, our results seem general in that phage treatments with Klebsiella pneumonia and Pseudomonas aeruginosa also generated persister cells. Hence, along with resistant strains, bacteria also form persister cells during phage infection.

In the 21st century, the world is facing persistent global problems that have led to 193 countries to agree on the 17 Sustainable Development Goals (SDGs). The United Nations introduced these goals in 2015 to find solutions that could help end poverty, promote prosperity and protect the planet (United Nations, 2016a). In this brief perspective, we will discuss the potential role of Streptomyces in achieving those SDGs, focusing it in the current strategies applied for discovering novel compounds and in some of the problems that must be faced (Figure 1).

Members of the genus Streptomyces are filamentous Gram-positive bacteria belonging to the phylum Actinobacteria. They are ubiquitous microorganisms mainly found in soil but they can also inhabit other niches like seawater or deserts, or living associated with other organisms (Sivalingam et al., 2019). Streptomyces is mainly known for its ability to produce a wide array of bioactive secondary metabolites, which have several interesting applications in different fields (Alam et al., 2022; Demain & Sanchez, 2009; Donald et al., 2022).

One of the problems that most concern the United Nations is the existence of a growing demand for food in today's world (Food security information network, 2023). In this context, Streptomyces could play a relevant role in achieving SDG 2 (zero hunger, improved nutrition and sustainable agriculture) and SDG 1 (end poverty). Streptomyces produces several metabolites with significant commercial relevance in enhancing the nutritional value of human food and animal feed, such as vitamins like cobalamin (Rex et al., 2022). Additionally, there is an increasing need for enzymes in the global market (Grand View Research, 2023). Streptomyces due to its wide metabolic potential is used for the sustainable biotechnological production of a broad assortment of enzymes such as proteases, xylanases, amylases, lipases, keratinases, cellulases, dextranases and chitinases among others (Fernandes de Souza et al., 2022; Kumar et al., 2020). These enzymes have applications in several fields, and advantages not only in terms of energy consumption, stability, substrate specificity, purity or reaction efficiency but also in ecological and waste generation, thus contributing to the achievement of sustainable industrialization and innovation (SDG 9) and promoting responsible production and consumption (SDG 12). An example of enzymes with ecological applications is the degradation of lignocellulose and dye decolourization by detergent-stable peroxidases and laccases (Cuebas-Irizarry & Grunden, 2024). These enzymes can be potentially used to treat wastewater resulting from human activities like textile and paper industries, which cause environmental pollution and wastes that affect life below

Chassis strains, derived from Streptomyces coelicolor M145, deleted for one or more of its four main specialized metabolites biosynthetic pathways (CPK, CDA, RED and ACT), in various combinations, were constructed for the heterologous expression of specialized metabolites biosynthetic pathways of various types and origins. To determine consequences of these deletions on the metabolism of the deleted strains comparative lipidomic and metabolomic analyses of these strains and of the original strain were carried out. These studies unexpectedly revealed that the deletion of the peptidic clusters, RED and/or CDA, in a strain deleted for the ACT cluster, resulted into a great increase in the triacylglycerol (TAG) content, whereas the deletion of polyketide clusters, ACT and CPK had no impact on TAG content. Low or high TAG content of the deleted strains was correlated with abundance or paucity in amino acids, respectively, reflecting high or low activity of oxidative metabolism. Hypotheses based on what is known on the bio-activity and the nature of the precursors of these specialized metabolites are proposed to explain the unexpected consequences of the deletion of these pathways on the metabolism of the bacteria and on the efficiency of the deleted strains as chassis strains.

Organohalides are widespread pollutants that pose significant environmental hazards due to their high degree of halogenation and elevated redox potentials, making them resistant to natural attenuation. Traditional bioremediation approaches, primarily relying on bioaugmentation and biostimulation, often fall short of achieving complete detoxification. Furthermore, the emergence of complex halogenated pollutants, such as per- and polyfluoroalkyl substances (PFASs), further complicates remediation efforts. Therefore, there is a pressing need to reconsider novel approaches for more efficient remediation of these recalcitrant pollutants. This review proposes novel redox-potential-mediated hybrid bioprocesses, tailored to the physicochemical properties of pollutants and their environmental contexts, to achieve complete detoxification of organohalides. The possible scenarios for the proposed bioremediation approaches are further discussed. In anaerobic environments, such as sediment and groundwater, microbial reductive dehalogenation coupled with fermentation and methanogenesis can convert organohalides into carbon dioxide and methane. In environments with anaerobic-aerobic alternation, such as paddy soil and wetlands, a synergistic process involving reduction and oxidation can facilitate the complete mineralization of highly halogenated organic compounds. Future research should focus on in-depth exploration of microbial consortia, the application of ecological principles-guided strategies, and the development of bioinspired-designed techniques. This paper contributes to the academic discourse by proposing innovative remediation strategies tailored to the complexities of organohalide pollution.

Marine microorganisms are increasingly recognized as primary producers of marine secondary metabolites, drawing growing research interest. Many of these organisms are unculturable, posing challenges for study. Metagenomic techniques enable research on these unculturable microorganisms, identifying various biosynthetic gene clusters (BGCs) related to marine microbial secondary metabolites, thereby unveiling their secrets. This review comprehensively analyses metagenomic methods used in discovering marine microbial secondary metabolites, highlighting tools commonly employed in BGC identification, and discussing the potential and challenges in this field. It emphasizes the key role of metagenomics in unveiling secondary metabolites, particularly in marine sponges and tunicates. The review also explores current limitations in studying these metabolites through metagenomics, noting how long-read sequencing technologies and the evolution of computational biology tools offer more possibilities for BGC discovery. Furthermore, the development of synthetic biology allows experimental validation of computationally identified BGCs, showcasing the vast potential of metagenomics in mining marine microbial secondary metabolites.

We here explore the potential of the fungal genus Aureobasidium as a prototype for a microbial chassis for industrial biotechnology in the context of a developing circular bioeconomy. The study emphasizes the physiological advantages of Aureobasidium, including its polyextremotolerance, broad substrate spectrum, and diverse product range, making it a promising candidate for cost-effective and sustainable industrial processes. In the second part, recent advances in genetic tool development, as well as approaches for up-scaled fermentation, are described. This review adds to the growing body of scientific literature on this remarkable fungus and reveals its potential for future use in the biotechnological industry.

Over time, humanity has addressed microbial water contamination in various ways. Historically, individuals resorted to producing beer to combat the issue. Fast forward to the 19th century, and we witnessed a scientific approach by Robert Koch. His groundbreaking gelatine plating method aimed to identify and quantify bacteria, with a proposed limit of 100 colony-forming units per millilitre (CFU/mL) to avoid Cholera outbreaks. Despite considerable advancements in plating techniques through experimentation with media compositions and growth temperatures, the reliance on a century-old method for water safety remains the state-of-the-art. Even though most countries succeed in producing qualitative water at the end of the production centres, it is difficult to control, and guarantee, the same quality during distribution. Rather than focusing solely on specific sampling points, we propose a holistic examination of the entire water network to ensure comprehensive safety. Current practices leave room for uncertainties, especially given the low concentrations of pathogens. Innovative methods like flow cytometry and flow cytometric fingerprinting offer the ability to detect changes in the microbiome of drinking water. Additionally, molecular techniques and emerging sequencing technologies, such as third-generation sequencing (MinION), mark a significant leap forward, enhancing detection limits and emphasizing the identification of unwanted genes rather than the unwanted bacteria/microorganisms itself. Over the last decades, there has been the realization that the drinking water distribution networks are complex ecosystems that, beside bacteria, comprise of viruses, protozoans and even isopods. Sequencing techniques to find eukaryotic DNA are necessary to monitor the entire microbiome of the drinking water distribution network. Or will artificial intelligence, big data and machine learning prove to be the way to go for (microbial) drinking water monitoring? In essence, it is time to transcend century-old practices and embrace modern technologies to ensure the safety of our drinking water from production to consumption.