Journal of Industrial Microbiology & Biotechnology最新文献

Rubromycins are bacterial aromatic polyketides containing a hallmark spiroketal pharmacophore produced by type II polyketide synthases and accessory enzymes. They generally display cytotoxic and antimicrobial properties, frequently disrupting cellular processes and proteins associated with nucleic acids, such as DNA helicase or telomerase. Among the known rubromycin congeners, hyaluromycin stands out due to a 2-amino-3-hydroxycyclopent-2-enone (C5N) substitution that is presumably installed by an amide bond synthetase (ABS). Here, we used bioinformatic analysis to identify uncharacterized biosynthetic gene clusters and potential rubromycin producer strains encoding putative ABSs but lacking the enzymes responsible for C5N formation, suggesting potentially novel substituents. One of these strains, Lentzea tibetensis, was successfully cultivated and confirmed to produce a previously undescribed aminocoumarin-substituted rubromycin polyketide, named coumarubrin, as verified by high-resolution mass spectrometry (HRMS) and comprehensive nuclear magnetic resonance (NMR) spectroscopy. Electronic circular dichroism spectroscopy indicates an absolute configuration identical to that of previously characterized rubromycins, while the first bioactivity assays demonstrated potent inhibitory activity against Gram-positive bacteria. One-Sentence Summary: This study reports the discovery of a novel member of the rubromycins, antibiotic and cytotoxic aromatic polyketides produced by Actinobacteria, which is fused to a distinct aminocoumarin moiety.

Glucosamine (GlcN) and GlcN-based supplements, e.g. glucosamine hydrochloride, glucosamine sulfate, and N-acetyl glucosamine (GlcNAc), provide symptomatic relief to osteoarthritis patients and have been used as one of the most popular nutraceuticals. To meet the increasing demands, scientists have explored cost-effective methods for GlcN and GlcNAc production using low-cost raw materials such as seafood waste. However, the commercially available GlcN and GlcNAc production methods are environmentally harmful because of the use of toxic reagents. Moreover, the raw material used might be unsafe for consumers with shrimp allergies. On the other hand, bio-based GlcN production is gaining popularity because of its eco-friendly production approach and optimum reaction conditions. In this mini-review, we will discuss the recent developments to produce GlcN and GlcNAc through (1) the chemical and enzyme-mediated approaches of crude chitin hydrolysis, primarily obtained from shrimp and crabs; (2) the whole cell-based systems for fungal derived chitin bio-transformation and fungal fermentation; and (3) the metabolic engineering and the adaptive evolution based microbial biocatalyst for a balanced cell growth and optimal production of GlcN and GlcNAc. One-Sentence Summary: This article summarizes the mechanism of glucosamine and N-acetyl glucosamine production using bacteria, fungi, and chemical processes.

In spite of wonderful industrial applications of microbial enzymes, still most of habitats in various parts of world are unexplored for bioprospecting of industrial potent microbes. This study represents the first bioprospecting effort in Layyah district to explore indigenous bacterial diversity, enzymatic potential, and phylogenetic relationships in untapped contaminated soil habitat. Contaminated soils serve as reservoirs of industrially significant bacteria with unique enzymatic degradation capabilities, offering solutions for sustainable industrial applications and environmental remediation. An effort for comparative bioprospecting-based study for bacterial diversity exhibiting amylase potential across unaddressed contaminated soil samples [industrial, household, poultry, and animal waste (AW)] using qualitative and quantitative methods, was conducted. AW-contaminated soil exhibited the highest bacterial load (2.51 × 1010 CFUs) and amylase activity (51, amylase zones), whereas industrial waste soil showed the lowest CFUs (1.24 × 1010). Household waste soil, however, displayed the greatest Shannon diversity index (H'= 2.192262) for amylase-producing bacteria. Among isolates, Priestia flexa AW3 (OQ446563) demonstrated exceptional amylase production, forming 30 mm hydrolysis zones on starch agar and achieving optimal activity (1.76 ± 0.05 OD; 1.23 ± 0.03 AU/mL) at pH 7 and 37°C after 48 h. Notably, the strain retained enzymatic stability under extreme conditions, temperature up to 50°C, NaCl concentrations (0.5%-10%), and a broad pH range. Phylogenetic analysis via 16S rRNA sequencing confirmed its identity as P. flexa. This study underscores the untapped potential of contaminated soils in Layyah as sources of robust industrial microbes and highlights the value of bioprospecting in discovering novel bacterial strains for biotechnology and environmental sustainability. One-Sentence Summary: Bioprospecting for industrially important bacteria with unique enzymatic potential from untapped habitats is highly needed to solve sever environmental problems.

Biocatalysis provides access to synthetically challenging molecules and commercially and pharmaceutically relevant natural product analogs while adhering to principles of green chemistry. Cytochromes P450 (P450s) are among the most superlative and versatile oxidative enzymes found in nature and are desired regio- and stereoselective biocatalysts, particularly for structurally complex hydrocarbon skeletons. We used 10 genome-sequenced Streptomyces strains, selected based on their preponderance of P450s, to biotransform the bioactive diterpenoid abietic acid. We isolated and structurally characterized seven oxidized abietic acid derivatives from three different strains, including four products that are new bacterial biotransformants or enzymatic products. Oxidations (hydroxylation, dehydrogenation, and aromatization) were seen on both the B and C rings of abietic acid and five products had multiple modifications. Notable conversions observed in the study were that of abietic acid to 15-hydroxy-7-oxo-8,11,13-abietatrien-18-oic acid, 7, which involves multiple hydroxylation reactions and dehydrogenation. The findings from this study will lead to identifying P450s or other enzymes that may act as general biocatalysts to modify abietanes and other labdane-type diterpenoid skeletons.

One-sentence summary: Genome-guided biotransformation of the bioactive diterpenoid abietic acid in Streptomyces yielded seven oxidized derivatives including four that have not been previously seen from bacteria.

Cyanobacteria are prolific producers of structurally diverse and biologically potent natural products, a subset of which feature guanidino moieties. Introduction and modification of the guanidine group confer tuned basicity and enable extensive hydrogen bonding, cation-π, and electrostatic interactions, facilitating high-affinity binding to numerous biological targets. Although the enzymatic processes responsible for guanidine modifications in cyanobacterial pathways remain somewhat obscure, recent investigations have begun to clarify the biosynthetic machinery that mediates these distinctive transformations. In this review, we summarize these advances, with particular emphasis on the enzymatic steps responsible for guanidine installation and tailoring. These enzymatic transformations include N-prenylation, cyclization, and tricyclic guanidinium formation, representing rare or previously undescribed biosynthetic strategies in nature. This review provides new insights into the metabolic and enzymatic versatility of cyanobacteria and a foundation for future advances in enzyme engineering and therapeutic discovery. One-Sentence Summary: This review highlights recent advances in understanding how cyanobacteria enzymatically install and modify guanidino groups to produce bioactive natural products.

Epoxyquinoids are a unique class of natural products featuring an epoxide embedded within a quinone/quinol scaffold, typically as an epoxycyclohexenone (ECH). Their striking stereochemical diversity arises from multiple permutations of epoxide and hydroxyl configurations across the epoxyquinol and epoxyhydroquinone families. These highly oxygenated cores contain contiguous stereocenters and reactive functionalities, and their structural diversity correlates with broad bioactivity spanning antibacterial, antifungal, antiparasitic, anti-inflammatory, and antiproliferative effects. A shared epoxide-quinone (or keto-epoxide) pharmacophore acts as an electrophilic warhead that covalently engages protein nucleophiles via Michael addition and epoxide opening, underpinning diverse modes of action. Recent biosynthetic advances have uncovered tailoring enzymes with unusual catalytic strategies that forge the epoxide, install additional functionality, and tune oxidation states through redox chemistry. This review highlights current knowledge of experimentally characterized pathways and enzyme functions across Actinobacteria, Ascomycota, and Basidiomycota, illuminating common logic and organism-specific innovations in epoxyquinoid assembly.

Citric acid possesses high economic value and is considered as the world's largest consumed organic acid in numerous industries. Citric acid applications range from food to beverage industries, pharmaceuticals, cosmetics, and the environment. It is mostly produced by microbial fermentation, but Aspergillus niger is considered as the main workhorse for large-scale production of citric acid. In the current review, special devotion has been made toward addressing the latest and innovative literature related to production of citric acid by A. niger. The review article discusses A. niger historical involvement in citric acid production, fermentation technologies, molecular biology, biosynthesis, accumulation of citric acid, methods for enhanced production of citric acid, different operational factors also influencing citric acid production, and various techniques used for citric acid recovery. Also, copious biotechnological applications of citric acid are summarized for a fundamental comprehension of the subject and its critical role in diverse fields of industries.

One-sentence summary: This review describes the historical role of Aspergillus niger in the production of citric acid, fermentation technologies, molecular biology, techniques for increased citric acid production, and other physical and chemical variables influencing the production of citric acid.

The equine gut harbors a diverse microbial community and represents a rich source of carbohydrate-active enzymes (CAZymes). To identify and characterize potentially novel CAZymes from a horse's hindgut metagenome, shotgun metagenomic sequencing was performed on DNA extracted from a stool sample of a male horse, followed by CAZyme annotation. Here, we report on the characterization of a novel enzyme (AH2) that was identified, synthesized, cloned, and characterized from the obtained CAZyme dataset. AH2 was identified as a GH130 family member and displayed exclusive xylanase activity, a trait hitherto unreported in prior characterization of GH130 CAZymes. AH2 displayed an optimal activity at a pH of 5.6 and a temperature of 50°C. AH2 maintained significant activity across a pH range of 4-10 (62-72%) and temperatures of 30-70°C (77-86%). The enzyme had remarkable stability, with minimal reductions in activity across a temperature range of 4-70°C and pH levels of 3, 7, and 9. Docking studies identified AH2's amino acids (Glu90 and Glu149) to be involved in substrate binding. Molecular dynamics simulation confirmed the structural stability of AH2 at pH 5.6 and 50°C, further supporting its resilience under these conditions. Our results expand on the known activities associated with the GH130 CAZyme family and demonstrate that the horse gut metagenome represents an unexplored source of novel CAZymes.

One-sentence summary: A novel activity for members of the CAZyme family GH130.

∆9-tetrahydrocannabinol (∆9-THC) and cannabidiol are the most abundant natural cannabinoids isolated from the different cultivars of the Cannabis plant. Other natural ∆9-THC analogs, especially those with different alkyl chain substitutions, display different and potent bioactivity. However, these rare cannabinoids are typically isolated in minuscule amounts and are difficult to synthesize. Targeted microbial biosynthesis can therefore be an attractive route to access such molecules. Here, we report the development of a Saccharomyces cerevisiae host to biosynthesize 2 rare cannabinoids from simple sugars. The yeast host is engineered to accumulate excess geranyl pyrophosphate, to overexpress a fungal pathway to 2,4-dihydroxy-6-alkyl-benzoic acids, as well as the downstream UbiA-prenyltransferase and ∆9-tetrahydrocannabinolic acid synthase. Two rare cannabinoid acids, the C1-substituted ∆9-tetrahydrocannabiorcolic acid (∼16 mg/L) and the C7-substituted ∆9-tetrahydrocannabiphorolic acid (∼5 mg/L) were obtained from this host; the latter was thermally decarboxylated to give ∆9-tetrahydrocannabiphorol. Given the diversity of fungal biosynthetic gene clusters that can produce resorcylic acids, this microbial platform offers the potential to produce other rare and new-to-nature cannabinoids. One Sentence Summary:  Saccharomyces cerevisiae as a host to produce rare cannabinoids.

Terephthalic acid, a key precursor for polyester production, is traditionally derived from fossil resources, contributing to global warming. Although numerous studies have explored the production of terephthalic acid from biomass polysaccharides, energy-intensive chemical processes are predominantly employed. In this study, we have developed a biochemical process to produce bio-based terephthalic acid from lignocellulosic biomass for reducing CO2 emissions. Among the tested six underutilized lignocellulosic biomasses, hardwood, with high cellulose contents of 52.8%, was subjected to alkaline pretreatment (165 °C for 2.5 hr) to eliminate lignin, and the resulting water-insoluble fraction was hydrolyzed by cellulases to yield monosaccharides. These monosaccharides were then biochemically transformed into terephthalic acid via p-tolualdehyde using two microorganisms, Phlebia sp. (a p-tolualdehyde-producing strain) and Comamonas testosteroni DSM6577. Comamonas testosteroni DSM6577 was used to oxidize the side chains of p-tolualdehyde into carboxylic acid to obtain terephthalic acid. This report describes the successful production of small amounts of bio-based terephthalic acid from lignocellulosic biomass. One-Sentence Summary: This paper shows that terephthalic acid, a key precursor for polyester production, can be produced from lignocellulosic biomass by microbial fermentation, which would contribute to reduce CO2 emission compared with other previous processes.