Advances in applied microbiology最新文献

The understanding of microbial diversity and their metabolic activities inside the oil reservoir is not well understood. The microbial community of the oil reservoir plays diversified roles from souring to microbial enhanced oil recovery. Therefore, studying community dynamics, phylogenetic diversity and ecological roles of the community inside the reservoir is crucial. This chapter discussed different microbial processes taking place in petroleum reservoirs. The study showed the crude oil being the major electron donor inside the reservoir supporting major life forms. The major metabolic reactions taking place are nitrate and nitrite reduction, sulfur and sulfate reduction, iron reduction, fermentation, and methanogenesis. Many of the thermo-tolerant strains that are capable of exploiting numerous energy sources and electron acceptors are among the most often cultured on functional groups, which include sulfate and sulfur reducing bacteria like Desulfacinum infernum, Desulfacinum subterraneum, iron reducing, fermentative such as Thermococcus, Thermotoga, and Thermoanaerobacter species, and methanogenic microorganisms like Methanothermobacter thermautotrophicus. The stimulated growth of microbes could also enhance the oil recovery from the reservoir by 66 percent as proved in some experimental studies. The microbial growth could be increased by injection of nitrate which could also control sulfide production, or nutrients such as sugar molasses that increases fermentative microbial growth, which could improve volumetric sweep efficiency and thus oil recovery. Microbial growth also has the potential for corrosion and souring due to the presence of microbes such as Desulfovibrio¸ Clostridium etc. It could be concluded that the scope of microbial diversity is far more extensive than what is known till date.

Blue-green algae, or cyanobacteria, is a diverse category of prokaryotic photosynthetic organisms. The capacity to extract economically viable compounds from cyanobacteria drives continuous scientific research in this domain. The ability to synthesize fatty acids from cyanobacteria makes them a useful substitute for animal and plant-based sources in the synthesis of oils and fats. Their benefits over other sources include their rapid growth rate, higher biomass production and minimal consumption of land. Since these substances build up inside of the cells, effective procedures for their extraction, recovery, and purification are required. The primary procedures in lipid extraction utilizing cyanobacteria are cultivation, biomass collection, cell disruption and lipid transesterification. Fatty acids are essential components of the metabolic pathways that generate and convert the majority of lipid classes. This chapter outlines the metabolic pathway associated with fatty acid biosynthesis, along with various mechanical and chemical methods that can be employed to extract lipids from cyanobacteria. The composition of fatty acids primarily impacts their characteristics and practical use. This chapter also gives a general overview of the variety of fatty acid profiles found in cyanobacteria, including omega-6 and omega-3 fatty acids, as well as odd-chain, long-chain, short-chain, and medium-chain fatty acids and the different uses of cyanobacterial fatty acids in various industries, such as aquaculture, biofuel, food industry, pharmaceuticals, cosmetics and more. In summary cyanobacterial fatty acids are essential in various fields, offering benefits for both ecosystems and emerging industries.

Heavy metals are widely used to satiate the demands of growing industrialization and modern life. However, the presence of metal in large quantities in the ecosystem significantly impacts all life forms, particularly microorganisms. Many bacterial strains have developed metal resistance genes (MRG) to survive in extreme conditions through various mechanisms, such as active efflux, sequestration, permeability barriers, or co-resistance with antibiotic resistance genes. Metagenomic analysis is a powerful approach that enables the exploration of the functional repertoire and diversity of microorganisms, providing deeper insights into the mechanisms underlying the development of MRGs, and the active metabolites they produce to adapt to the polluted environments. With the advancement of these techniques, the knowledge can be further applied to environmental applications, such as bioremediation, biomonitoring, and synthetic biology. Bacteria with metal toxicity tolerance can be employed to enhance environmental sustainability and mitigate potential hazards.

Edible mushrooms are a valuable source of protein, dietary fiber, vitamins, essential elements, and bioactive compounds with significant nutraceutical benefits for human health. Their popularity has grown in recent years due to their gluten-free nature and essential amino acid profile, making them appealing to vegetarians, vegans, and individuals with celiac disease. The nutritional composition and biological efficiency of mushrooms depend on the species and production system, particularly the substrate used and cultivation conditions. This review explores how different substrates, particularly those containing agribusiness by-products, affect mushrooms' productivity, nutritional, and element content from the Agaricus, Lentinula, and Pleurotus genera. It underscores the importance of these mushrooms in the human diet and highlights how using agro-industrial wastes as substrates offers a sustainable cultivation method. This approach supports a circular bioeconomy, providing an ecologically and economically viable solution while aiding in waste recovery and minimizing environmental impacts associated with improper disposal of agro-industrial wastes.

Comamonas testosteroni TA441 is a model bacterium for aerobic steroid degradation. This review summarizes its steroid degradation pathways, including the genetic organization and enzymatic mechanisms involved in C17-side chain degradation, A,B-ring cleavage, and β-oxidation of B,C,D-rings. Comparative insights from other aerobic steroid-degrading bacteria highlight the evolutionary conservation of key enzymes. Understanding these pathways provides crucial insights into microbial steroid metabolism and its environmental significance.

Serotonin is a widely distributed monoamine neurotransmitter that plays a critical role in emotion regulation and management in animals. It also serves as a key intermediate in the melatonin biosynthesis pathway. Melatonin is crucial for circadian rhythm regulation, antioxidant defense, and plant growth as well as stress resistance. Both serotonin and melatonin are involved in signaling transduction pathways that modulate various nervous system activities. Currently, serotonin is primarily obtained through natural extraction and chemical synthesis. However, these methods are time-consuming, low-yielding, and environmentally unfriendly. In recent years, environmentally friendly bio-fabrication has garnered significant attention. Microbial synthesis, characterized by short growth cycles and eco-friendly production processes, has emerged as a promising platform for the synthesis of serotonin and melatonin. Nevertheless, the production yield of serotonin and melatonin in microorganisms remains insufficient to meet industrial production demands. This review provides a comprehensive overview of the fundamental properties and physiological functions of serotonin and melatonin with a focus on their biosynthesis. In addition, it examines recent advancements in microbial biosynthesis of serotonin and melatonin, identifies key bottlenecks limiting production efficiency, and proposes metabolic engineering strategies to enhance microbial synthesis efficiency, aiming for scalable industrial applications.

Microbial pesticides derived from entomopathogenic bacteria occupy the greater share of the global biopesticides market. Since the late 1990s, the exploration of such bacterial species has intensified and expanded beyond the well-described Bacillus thuringiensis to other spore-forming Gram-positive bacteria including Brevibacillus laterosporus and Lysinibacillus sphaericus. Among the non-spore-forming Gram-negative bacteria Chromobacterium spp., Serratia spp., and Pseudomonas spp. are of interest for their insect active properties. Unfortunately, all these bacterial species are susceptible to the effects of some putative antibacterial proteins (ABPs), including bacteria-eating viruses (phages), encapsulins, and phage tail-like bacteriocins (PTLBs). Phage-derived bacteriocins can be either contractile phage tail-like (R-type) or non-contractile tail-like (F-type) structures. Encapsulins, a class of high molecular-weight (HMW) putative ABPs resembling phage capsid or head-like structures have been identified in different bacterial species. These putative ABPs are known to pose a serious threat to the mass production of these useful bacteria by causing a collapse of the culture through lysis of the cells. For instance, B. thuringiensis specific phages can cause production batch failures ranging from 15 to 100%. Recently, the stunted growth of the insect pathogenic B. laterosporus strains 1821L and 1951 from New Zealand has been associated with production of HMW putative ABPs of 31.4 kDa, Linocin M18, and ∼48 kDa, phage-like element PBSX-protein XkdK. This article provides an overview of the biological attributes of the putative ABPs and their implications in harnessing the insecticidal potential of B. thuringienesis and the emerging biocontrol agent B. laterosporus.

Mycotoxins are secondary metabolites produced by a wide variety of filamentous fungi. These compounds are toxic to humans and animals, and, in several cases, also to invertebrates, plants and microbial cells. Contamination of food and feed with mycotoxins can occur at different stages of the production chain, thus making mycotoxins a very important dietary risk factor. Various methods based on physical and chemical principles can be implemented to mitigate mycotoxin contamination. However, these methods possess two important disadvantages: the generation of toxic residues and the alteration of the nutritional and palatability qualities. Several bacterial and fungal species can detoxify mycotoxins by adsorption and/or biotransformation. Adsorption implies the interaction of the mycotoxin with a cellular component, while biotransformation is the chemical modification of the toxin. There are plenty of examples that demonstrate that detoxification of mycotoxins employing microbial cells or microbial enzymes is an environmentally friendly, efficient, specific and safe method. This chapter focuses on the biological detoxification of structurally different mycotoxins by adsorption to microbial cells or microbial biotransformation. It includes a comprehensive review of the discovery of the most critical mycotoxins, the use of probiotics to remove mycotoxins by surface adsorption, and the microbial biotransformation reactions, products, and mechanisms known to date that result in the detoxification of aflatoxins, fumonisins, zearalenone, ochratoxins, trichothecenes, patulin and fusaric acid.

Carbon metabolism is an essential process in fungal physiology, balancing energy availability, growth, and survival through the assimilation and breakdown of organic carbon sources. This review focuses on three major families of oxidoreductases that play central roles in fungal carbon metabolism: PF00248, PF00106, and PF00107. These enzymes are not only crucial for energy production but also for the synthesis and breakdown of complex organic molecules. PF00248, the aldo-keto reductase superfamily, is involved in a wide range of redox reactions, while PF00106 includes diverse short-chain reductase/dehydrogenases important for fungal growth and environmental adaptation. PF00107 comprises zinc-binding dehydrogenases with a role in processes such as alcohol metabolism and zinc uptake. These oxidoreductases are evolutionarily conserved with respect to amino acid sequence motifs but show significant genetic diversity across fungal species, reflecting their ecological adaptability and metabolic versatility. Understanding the functions within these enzyme families can enhance the design of efficient fungal cell factories for biotechnological applications, such as biofuel and biochemical production from plant biomass. This review highlights the importance of these enzymes in central carbon metabolism and their potential for industrial applications.

Mercury occurs in inorganic and organic forms in abiotic and biotic environments, food and humans. Diet is a primary pathway to chronic exposure and the Hg content of food is regulated, including the three most cultivated edible fungi. The reliable determination of total Hg and organo-Hg compounds in fungi is therefore crucial from the regulatory and human exposure viewpoint. So far, no fungal species have been identified that exhibit mercury hyperaccumulation. Chronologically, external fungal biomass decomposition, elementary Hg⁰ vapour generation and cold vapour-atomic absorption spectroscopy measurement was the first popular instrument technique used to measure Hg in mushrooms. In more recent time, chemical vapour generation - atomic fluorescence spectrometry is getting more popular. Radiochemical analysis, instrumental neutron activation analysis, electrothermal atomic absorption spectrometry and electrochemical techniques (anodic stripping voltammetry, differential pulsed anodic stripping voltammetry and potentiometry) were occasionally used. More recently and going forward, ICP-MS technique that allow precise measurement of multiple elements including Hg simultaneously are likely to most widely used. For speciation studies of Hg in fungal biomass, CV-AAS and a variation of the instrumental couplings of gas- and liquid chromatography (combined with chemical vapor generation) and non-chromatographic separations with various detectors have been used. From the use of L-cysteine as a complexing agent to the quantitative capture and determination of MeHg in various matrices, a number of applications, modifications and updates to the methodology have been introduced since then. L-cysteine has the potential to capture MeHg, EtHg and PhHg or possibly any organo-Hg compound in a sample extract.