Journal of Industrial Microbiology & Biotechnology最新文献

There is a growing interest in developing a methodology for effectively cleaving carbon-carbon (C-C) bonds in polymer backbones through bioconversion processes that utilize microorganisms and their enzymes. This upsurge of interest is driven by the goal of achieving a circular economy. Polyolefin post-consumer plastics are a substantial source of carbon, but the recycling potential is severely limited. Upcycling routes are needed for converting polyolefin post-consumer plastics into value-added products while concurrently mitigating adverse environmental effects. These materials contain carbon-based chemicals that can, in principle, serve as the feedstock for microbial metabolism. Some microbes have been reported to grow on polyolefin plastics, but the rate of biodegradation is insufficient for industrial processes. In this study, low-density polyethylene (LDPE) films were subjected to two mild ozone-based oxidation treatments, which facilitated biodegradation. The degree of oxidation was determined by Fourier transform infrared spectroscopy via analysis of the carbonyl index (1,710/1,460 cm-1), which ranged from 0.3 to 2.0, and also via analysis of the carboxylic acid content. Following oxidation of the films, studies were conducted to investigate the ability of a panel of polyvinyl alcohol-degrading microbes to degrade the oxidized films. A defined minimal medium was used to cultivate and assess microbial growth on the oxidized films. Following 45 days of cultivation, the most effective strains were further cultivated up to three additional generations on the oxidized film substrates to improve their ability to degrade the oxidized LDPE films. After these enrichments, we identified a strain from the third generation of Pseudomonas sp. Rh926 that exhibited significant cell growth and reduced the oxidized LDPE film mass by 25% in 30 days, demonstrating an enhanced capacity for degrading the oxidized LDPE films.

One-sentence summary: Discovery and adaptation techniques were used to enhance the metabolic capability of microorganisms for increased biodegradation of ozone-oxidized LDPE films as a step toward a future upcycling process.

The filamentous fungus Trichoderma reesei is a mesophilic ascomycete commercially used to produce industrial enzymes for a variety of applications. Strain improvement efforts over many years have resulted not only in more productive hosts, but also in undesirable traits such as the need for lower temperatures to achieve maximum protein secretion rates. Lower fermentation temperatures increase the need for cooling resulting in higher manufacturing costs. We used a droplet-based evolution strategy to increase the protein secretion temperature of a highly productive T. reesei whole cellulase strain from 25°C to 28°C by first isolating an improved mutant and subsequently tracing the causative high-temperature mutation to one gene designated gef1. An industrial host with a gef1 deletion was found to be capable of improved productivity at higher temperature under industrially relevant fermentation conditions.

One-sentence summary: High-temperature droplet-based evolution resulted in the identification of a mutation in Trichoderma reesei gef1 enabling high productivity at elevated temperatures.

The increasing global population and climate change pose significant challenges to agriculture, particularly in managing plant diseases caused by phytopathogens. Traditional methods, including chemical pesticides and antibiotics, have become less effective due to pathogen resistance and environmental concerns. Phage therapy emerges as a promising alternative, offering a sustainable and precise approach to controlling plant bacterial diseases without harming beneficial soil microorganisms. This review explores the potential of bacteriophages as biocontrol agents, highlighting their specificity, rapid multiplication, and minimal environmental impact. We discuss the historical context, current applications, and prospects of phage therapy in agriculture, emphasizing its role in enhancing crop yield and quality. Additionally, the paper examines the integration of phage therapy with modern agricultural practices and the development phage cocktails and genetically engineered phages to combat resistant pathogens. The findings suggest that phage therapy could revolutionize phytopathological management, contributing to global food security and sustainable agricultural practices.

One-sentence summary: The burden of plant diseases and phage-based phytopathological treatment.

Hybrid natural products are compounds that originate from diverse biosynthetic pathways and undergo a conjugation process, which enables them to expand their chemical diversity and biological functionality. Terpene-amino acid meroterpenoids have garnered increasing attention in recent years, driven by the discovery of noteworthy examples such as the anthelmintic CJ-12662, the insecticidal paeciloxazine, and aculene A (1). In the biosynthesis of terpene-amino acid natural products, single-module nonribosomal peptide synthetases (NRPSs) have been identified to be involved in the esterification step, catalyzing the fusion of modified terpene and amino acid components. Despite prior investigations into these NRPSs through gene deletion or in vivo experiments, the enzymatic basis and mechanistic insights underlying this family of single-module NRPSs remain unclear. In this study, we performed biochemical characterization of AneB by in vitro characterization, molecular docking, and site-directed mutagenesis. The enzyme reaction analyses, performed with L-proline and daucane/nordaucane sesquiterpene substrates, revealed that AneB specifically esterifies the C10-OH of aculenes with L-proline. Notably, in contrast to ThmA in CJ-12662 biosynthesis, which exclusively recognizes oxygenated amorpha-4,11-diene sesquiterpenes for L-tryptophan transfer, AneB demonstrates broad substrate selectivity, including oxygenated amorpha-4,11-diene and 2-phenylethanol, resulting in the production of diverse unnatural prolyl compounds. Furthermore, site-directed mutagenesis experiments indicated the involvement of H794 and D798 in the esterification catalyzed by AneB. Lastly, domain swapping between AneB and ThmA unveiled that the A‒T domains of ThmA can be effectively harnessed by the C domain of AneB for L-tryptophan transfer, thus highlighting the potential of the C domain of AneB for generating various terpene-amino acid meroterpenoid derivatives.

One-sentence summary: The enzymatic basis and mechanistic insights into AneB, a single-module NRPS, highlight its capacity to generate various terpene-amino acid meroterpenoid derivatives.

The chemo-enzymatic and enzymatic synthesis of heparan sulfate and heparin are considered as an attractive alternative to the extraction of heparin from animal tissues. Sulfation of the hydroxyl group at position 2 of the deacetylated glucosamine is a prerequisite for subsequent enzymatic modifications. In this study, multiple strategies, including truncation mutagenesis based on B-factor values, site-directed mutagenesis guided by multiple sequence alignment, and structural analysis were performed to improve the stability and activity of human N-sulfotransferase. Eventually, a combined variant Mut02 (MBP-hNST-NΔ599-602/S637P/S741P/E839P/L842P/K779N/R782V) was successfully constructed, whose half-life at 37°C and catalytic activity were increased by 105-fold and 1.35-fold, respectively. After efficient overexpression using the Escherichia coli expression system, the variant Mut02 was applied to N-sulfation of the chemically deacetylated heparosan. The N-sulfation content reached around 82.87% which was nearly 1.88-fold higher than that of the wild-type. The variant Mut02 with high stability and catalytic efficiency has great potential for heparin biomanufacturing.

Biomanufacturing could contribute as much as ${$}$30 trillion to the global economy by 2030. However, the success of the growing bioeconomy depends on our ability to manufacture high-performing strains in a time- and cost-effective manner. The Design-Build-Test-Learn (DBTL) framework has proven to be an effective strain engineering approach. Significant improvements have been made in genome engineering, genotyping, and phenotyping throughput over the last couple of decades that have greatly accelerated the DBTL cycles. However, to achieve a radical reduction in strain development time and cost, we need to look at the strain engineering process through a lens of optimizing the whole cycle, as opposed to simply increasing throughput at each stage. We propose an approach that integrates all 4 stages of the DBTL cycle and takes advantage of the advances in computational design, high-throughput genome engineering, and phenotyping methods, as well as machine learning tools for making predictions about strain scale-up performance. In this perspective, we discuss the challenges of industrial strain engineering, outline the best approaches to overcoming these challenges, and showcase examples of successful strain engineering projects for production of heterologous proteins, amino acids, and small molecules, as well as improving tolerance, fitness, and de-risking the scale-up of industrial strains.