Advances in applied microbiology最新文献

Carbohydrates play an important role in the life cycle. Among them, functional oligosaccharides show a complex and diverse structures with unique physiological activities and biological functions. However, different preparation methods directly affect the structure, molecular weight, and other functions of oligosaccharides, as well as their application fields and manufacturing costs. In the preparation of β-1,3-glucan oligosaccharides (OBGs), water insolubility of β-1,3-glucans hampers the hydrolysis efficiency. The synthesis of some functional oligosaccharides requires the consumption of energy substrates, such as ATP, CTP, and uridine triphosphate, for sugar nucleotide synthesis, leading to increased capital costs. A more economical solution to solve energy supply is to adopt microbial cocultivation or cellular nucleoside triphosphate regeneration. This review focused on the sources, preparation methods, biological activities of OBG, and the cultivation methods and applications of microbial cocultivation and fermentation. We also reviewed the preparation methods of other functional oligosaccharides, such as sialylated oligosaccharides, β-nicotinamide mononucleotide, and α-galacto-oligosaccharides.

l-lysine is an essential amino acid that contains various functional groups including α-amino, ω-amino, and α-carboxyl groups, exhibiting high reaction potential. The derivatization of these functional groups produces a series of value-added chemicals, such as cadaverine, glutarate, and d-lysine, that are widely applied in the chemical synthesis, cosmetics, food, and pharmaceutical industries. Here, we review recent advances in the biotechnological production of l-lysine and its derivatives and expatiate key technological strategies. Furthermore, we also discuss the existing challenges and potential strategies for more efficient production of these chemicals.

Microbial lipid production has been studied extensively for years; however, lipid metabolic engineering in many of the extraordinarily high lipid-accumulating yeasts was impeded by inadequate understanding of the metabolic pathways including regulatory mechanisms defining their oleaginicity and the limited genetic tools available. The aim of this review is to highlight the prominent oleaginous yeast genera, emphasizing their oleaginous characteristics, in conjunction with diverse other features such as cheap carbon source utilization, withstanding the effect of inhibitory compounds, commercially favorable fatty acid composition-all supporting their future development as economically viable lipid feedstock. The unique aspects of metabolism attributing to their oleaginicity are accentuated in the pretext of outlining the various strategies successfully implemented to improve the production of lipid and lipid-derived metabolites. A large number of in silico data generated on the lipid accumulation in certain oleaginous yeasts have been carefully curated, as suggestive evidences in line with the exceptional oleaginicity of these organisms. The different genetic elements developed in these yeasts to execute such strategies have been scrupulously inspected, underlining the major types of newly-found and synthetically constructed promoters, transcription terminators, and selection markers. Additionally, there is a plethora of advanced genetic toolboxes and techniques described, which have been successfully used in oleaginous yeasts in the recent years, promoting homologous recombination, genome editing, DNA assembly, and transformation at remarkable efficiencies. They can accelerate and effectively guide the rational designing of system-wide metabolic engineering approaches pinpointing the key targets for developing industrially suitable yeast strains.

Accidental spills and the misuse of chemicals may lead to current and legacy environmental contamination and pose concerns over possible (eco)toxicological secondary effects and risks toward non-target microbes and higher eukaryotes, including humans, in ecosystems. In the last decades, scientists and regulators have faced requests to thoroughly screen, prioritize and predict the possible deleterious effects of the huge numbers of existing and emerging xenobiotics, wastewaters and environmental samples on biological systems. In this context, it has become necessary to develop and validate (eco)toxicity bioassays based on microorganisms (e.g., bacteria, microalga, yeast, filamentous fungi, protozoa) as test-organisms whose data should be meaningful for environmental (micro)organisms that may be exposed to contaminated environments. These generally simple, fast and cost-effective bioassays may be preliminary and complementary to the more complex and long-term whole-organism animal-based traditional ecotoxicity tests. With the goal of highlighting the potential offered by microbial-based bioassays as non-animal alternatives in (eco)toxicity testing, the present chapter provides an overview of the current state-of-the art in the development and use of microbial toxicity bioassays through the examination of relatively recent examples with a diverse range of toxicity endpoints. It goes into the (eco)toxicological relevance of these bioassays, ranging from the more traditional microalga- and bacterial-based assays already accepted at regulatory level and commercially available to the more innovative microbial transcriptional profiling and gene expression bioassays, including some examples of biosensors.

Fungal pathogens now account for an unprecedented burden on human health. Like all microorganisms, these fungi must successfully forage for essential micronutrients such as zinc in order to proliferate. However, pathogenic microbes face an additional hurdle in securing zinc from their environment: the action of host nutritional immunity which strictly manipulates microbial access to this essential, but also potentially toxic trace metal. This review introduces the relevant pathogenic species and goes on to cover the molecular mechanisms of zinc uptake by human fungal pathogens. Fungi scavenge zinc from their environment via two basic mechanisms: via a family of cellular zinc importers-the ZIP transporters; and via a unique secreted zinc binding protein-the zincophore. However the genetic requirement of these systems for fungal virulence is highly species-specific. As well as zinc scarcity, potential intoxification with this heavy metal can occur and, unlike bacteria, fungi deal with environmental insult this via intraorganellar compartmentalization. Zinc availability also modulates the morphogenic behavior of a subset of pathogenic yeast species. This chapter will cover these different aspects of zinc availability on the physiology of human fungal pathogens with emphasis on the major pathogenic species Candida albicans.

Among photosynthetic microorganisms, Cyanobacteria and Microalgae species have been highly studied thank to their high value-added compounds for several industrial applications. Thus, their production is increasing in the last decade to produce raw material for cosmetics. In fact, the daily routine includes the use of cosmetics and sunscreens to protect against the environmental changes, mainly the increment of ultraviolet (UV) radiation rate with a consequent skin damage and premature aging due to this overexposure. As it is well discussed, chemical UV filters are extensively incorporated into sunscreens formulas; however, they can induce allergenic reactions as well. For these reasons, some pigments derived from microalgae, such as astaxanthin, lutein, β-carotene as well as other biocompounds are now well described in the literature as well as biotechnologically manufactured as natural ingredients to be incorporated into skin care products with multifunctional benefits even for sunscreen purposes. Hence, this investigation summarizes the recent studies about the main pigments from photosynthetic microorganisms' biomasses as well as their uses in dermocosmetics with novel attributes, such as anti-aging agents, makeups, skin lightening and whitening, among others.

Carbon one industry flux gas generated from fossil fuels, various industrial and domestic waste, as well as lignocellulosic biomass provides an innovative raw material to lead the sustainable development. Through the chemical and biological processing, the gas mixture composed of CO, CO₂, and H₂, also termed as syngas, is converted to biofuels and high-value chemicals. Here, the syngas fermentation process is elaborated to provide an overview. Sources of syngas are summarized and the influences of impurities on biological fermentation are exhibited. Acetogens and carboxydotrophs are the two main clusters of syngas utilizing microorganisms, their essential characters are presented, especially the energy metabolic scheme with CO, CO₂, and H₂. Synthetic biology techniques and microcompartment regulation are further discussed and proposed to create a high-efficiency cell factory. Moreover, the influencing factors in fermentation and products in carboxylic acids, alcohols, and others such like polyhydroxyalkanoate and poly-3-hydroxybutyrate are addressed. Biological fermentation from carbon one industry flux gas is a promising alternative, the latest scientific advances are expatiated hoping to inspire more creative transformation.

Isoprenoids, as the largest group of chemicals in the domains of life, constitute more than 50,000 members. These compounds consist of different numbers of isoprene units (C₅H₈), by which they are typically classified into hemiterpenoids (C5), monoterpenoids (C10), sesquiterpenoids (C15), diterpenoids (C20), triterpenoids (C30), and tetraterpenoids (C40). In recent years, isoprenoids have been employed as food additives, in the pharmaceutical industry, as advanced biofuels, and so on. To realize the sufficient and efficient production of valuable isoprenoids on an industrial scale, fermentation using engineered microorganisms is a promising strategy compared to traditional plant extraction and chemical synthesis. Due to the advantages of mature genetic manipulation, robustness and applicability to industrial bioprocesses, Saccharomyces cerevisiae has become an attractive microbial host for biochemical production, including that of various isoprenoids. In this review, we summarized the advances in the biosynthesis of isoprenoids in engineered S. cerevisiae over several decades, including synthetic pathway engineering, microbial host engineering, and central carbon pathway engineering. Furthermore, the challenges and corresponding strategies towards improving isoprenoid production in engineered S. cerevisiae were also summarized. Finally, suggestions and directions for isoprenoid production in engineered S. cerevisiae in the future are discussed.

Yeasts and humans have had a close relationship for millenia. Yeast have been used for food production since the first human societies. Since then, alternative uses have been discovered. Nowadays, antibiotic resistance constitutes a pressing need worldwide. In order to overcome this threat, one of the most important strategies is the search for new antimicrobials in natural sources. Moreover, biopreservation based on natural sources has emerged as an alternative to more common chemical preservatives. Yeasts constitute an underexploited source of antagonistic activity against other microorganisms. Here, we compile a summary of the antagonistic activity of yeast origin against other yeast and other microorganisms, such as bacteria or parasites. We present the mechanisms of action used by yeasts to display these activities. We also provide applications of these antagonistic activities in food industry and agriculture, medicine and veterinary, where yeast promise to play a pivotal role in the near future.