Advances in applied microbiology最新文献

Lactic acid bacteria (LAB) are ubiquitous bacteria associated with spontaneous lactic fermentation of vegetables, dairy and meat products. They are generally recognized as safe (GRAS), and they are involved in transformation of probiotic lacto-fermented foods, highly desired for their nutraceutical properties. The antifungal activity is one of the exciting properties of LAB, because of its possible application in food bio-preservation, as alternative to chemical preservatives. Many recent research works have been developed on antifungal activity of LAB, and they demonstrate their capacity to produce various antifungal compounds, (i.e. organic acids, PLA, proteinaceous compounds, peptides, cyclic dipeptides, fatty acids, and other compounds), of different properties (hydrophilic, hydrophobic and amphiphilic). The effectiveness of LAB in controlling spoilage and pathogenic fungi, demonstrated in different agricultural and food products, can be due to the synergistic effect between their antifungal compounds of different properties; where the amphiphilic-compounds allow the contact between the target microbial cell (hydrophilic compartment) and antifungal hydrophobic-compounds. Further studies on the interaction between compounds of these three properties are to de be developed, in order to highlight more their mechanism of action, and make LAB more profitable in improving shelf life and nutraceutical properties of foods.

Temperature-dependent composting is a challenging task but is worthy if it is done in the right manner. Cold composting has been known to be practiced since ancient times but there were not enough advancements to overcome the long mesophilic phase and bring the compost maturation to a short period. The composting processes that have been well practiced are discussed and the role of psychrotrophic bacteria that produce cold tolerant hydrolytic enzymes has been highlighted. In this chapter, the mechanism of substrate degradation has been elaborated to better understand the need of specific bacteria for a specific kind of substrate allowing fast and efficient decomposition. This chapter attempts to pave an appropriate way and suggest the best-suited method of composting for efficient production of compost by the conservation of heat in cold regions.

The term Gain-of-Function (GoF) describes the gain of new functions by organisms through genetic changes, which can naturally occur or by experimental genetic modifications. Gain-of-Function research on viruses is enhancing transmissibility, virus replication, virulence, host range, immune evasion or drug and vaccine resistance to get insights into the viral mechanisms, to create and analyze animal models, to accelerate drug and vaccine development and to improve pandemic preparedness. A subset is the GoF research of concern (GOFROC) on enhanced potentially pandemic pathogens (ePPPs) that could be harmful for humans. A related issue is the military use of research as dual-use research of concern (DURC). Influenza and coronaviruses are main research targets, because they cause pandemics by airborne infections. Two studies on avian influenza viruses initiated a global debate and a temporary GoF pause in the United States which ended with a new regulatory framework in 2017. In the European Union and China, GoF and DURC are mainly covered by the legislation for laboratory safety and genetically modified organisms. After the coronavirus outbreaks, the GoF research made significant advances, including analyses of modified MERS-like and SARS-like viruses and the creation of synthetic SARS-CoV-2 viruses as a platform to generate mutations. The GoF research on viruses will still play an important role in future, but the need to clarify the differences and overlaps between GoF research, GOFROC and DURC and the need for specialized oversight authorities are still debated.

Feed amino acids have numerous applications, and the market demand for them is likely to grow. Microbial cell factories promise the sustainable production of feed amino acids; however, their performance is significantly affected by the availability of precursors, carbon metabolic flux, and transporter systems. To circumvent these potential roadblocks, high-performance microbial cell factories have been constructed by strengthening the supply of precursors, increasing metabolic pathway flux, and engineering transporters. In this review, limiting factors and recent technical advances affecting the production of feed amino acids in microbial cell factories are discussed. In addition, existing challenges and potential strategies for increasing the output of these amino acids are described.

Nanoparticles (NPs), which have unique properties due to their extremely small size and high surface area to volume ratio, have attracted considerable attention and become an important tool for innovation in various fields. Traditionally, NPs are synthesized by physical and chemical processes, but these methods have high capital costs and energy demand, and involve the use of toxic and hazardous chemicals, which are prone to secondary pollution of the environment. In recent years, the use of microorganism-mediated methods has emerged as an alternative to traditional physical and chemical methods. The synthesis of NPs by microorganism has the advantages of non-toxicity, eco-friendliness, low-cost, reproducibility in production, easy amplification, and well-defined morphology. Probiotics are a kind of active microorganisms beneficial to the host. Compared with other microorganisms, probiotics are characterized by non-pathogenicity, rapid growth and regulation of gene expression, and produce a variety of proteins and enzymes involved in the synthesis of NPs. Therefore, the production of NPs using probiotics is an environmentally friendly and commercially attractive method, which provides new ideas and approaches for the application of NPs in the fields of biomedicine, agriculture and environmental remediation. This review aims to summarize the literature on the biosynthesis of NPs by probiotics and their synthetic mechanisms and applications.

An electromagnetic field (EMF) has been shown to have various stimulatory or inhibitory effects on microorganisms. Over the years, growing interest in this topic led to numerous discoveries suggesting the potential applicability of EMF in biotechnological processes. Among these observations are stimulative effects of this physical influence resulting in intensified biomass production, modification of metabolic activity, or pigments secretion. In this review, we present the current state of the art and underline the main findings of the application of EMF in bioprocessing and their practical meaning in process engineering using examples selected from studies on bacteria, archaea, microscopic fungi and yeasts, viruses, and microalgae. All biological data are presented concerning the classification of EMF. Furthermore, we aimed to highlight missing parts of contemporary knowledge and indicate weak spots in the approaches found in the literature.

Petri dish contaminations are commonplace and personally witnessed by every microbiologist. The vast majority of such contaminations result in nothing more than annoyance following which the Petri dishes are discarded. However, a handful of incidents of contaminations have led to momentous outcomes, the most renowned of which being that perceived by Alexander Fleming on the basis of the immense number of lives saved by penicillin. Petri dish contaminations as reported upon in the literature fall broadly into two categories; those in which the contaminant caused antagonism toward the species being cultured, and those in which the contaminant was established to be a species novum. Accounts of both of these categories of contaminations are set out here.

Lignocellulosic biomass is an abundant and renewable resource, and its utilization has become the focus of research and biotechnology applications as a very promising raw material for the production of value-added compounds. Filamentous fungi play an important role in the production of various lignocellulolytic enzymes, while some of them have also been used for the production of important metabolites. However, wild type strains have limited efficiency in enzyme production or metabolic conversion, and therefore many efforts have been made to engineer improved strains. Examples of this are the manipulation of transcriptional regulators and/or promoters of enzyme-encoding genes to increase gene expression, and protein engineering to improve the biochemical characteristics of specific enzymes. This review provides and overview of the applications of filamentous fungi in lignocellulosic biomass based processes and the development and current status of various molecular engineering strategies to improve these processes.

Nitrogen oxides (NO_x) and mercury (Hg) are commonly found coexistent pollutants in combustion flue gas. Ever-increasing emission of atmospheric Hg and NO_x has caused considerable environmental risks. Traditional flue gas demercuration and denitration techniques have many socioeconomic, technological and environmental drawbacks. Biotechnologies can be a promising and prospective alternative strategy. This article discusses theoretical foundation (biochemistry and genomic basis) and technical potentials (Hg⁰ bio-oxidation coupled to denitrification) of bioremoval of Hg and NO_x in flue gas and summarized recent experimental and technological advances. Finally, several specific technical perspectives have been put forward to better guide future researches.