Journal of Industrial Microbiology & Biotechnology最新文献

{"title":"The biosynthetic gene cluster landscape of the oral microbiome across health and dental caries.","authors":"McKenna Loop Yao, Peijun Lin, Kailey Hua, Wenjun Zhang","doi":"10.1093/jimb/kuag005","DOIUrl":"10.1093/jimb/kuag005","url":null,"abstract":"<p><p>Specialized metabolites encoded by biosynthetic gene clusters (BGCs) in the oral microbiome remain largely unexplored in the context of oral health and disease. Previous genome-centric surveys have identified hundreds of uncharacterized BGCs in the oral cavity associated with health and disease, but these studies relied on reference genomes and did not capture strain-level variation or the native distribution of BGCs. Here, we assembled three independently sourced metagenomic datasets from healthy and dental caries samples, extracted BGCs, and quantified their metagenomic abundance and transcriptional activity. We found that aryl polyene, ribosomally synthesized and post-translationally modified peptide (RiPP), and nonribosomal peptide (NRP) encoding BGCs were the most prominent BGCs identified across the three metagenomic datasets. We grouped the identified BGCs into homology-based gene cluster families (GCFs) and found that specific GCFs were consistently associated with either health or caries across diverse taxa, suggesting that some specialized metabolites may perform conserved ecological functions. Conversely, other BGCs showed more restricted taxonomic distributions and were linked to disease-associated taxa, such as Propionibacterium acidifaciens, suggesting niche-specific biosynthetic capacities within the oral environment. Applying elastic-net regression to the metatranscriptomic dataset further identified a subset of 51 BGCs out > 3 000 that distinguished healthy from caries samples, reinforcing the discriminatory power of BGC expression patterns. Together, these results demonstrate that BGCs provide functional resolution beyond taxonomic profiling and that BGC expression, rather than genomic presence alone, differentiates oral microbial community states. This underscores the relevance of specialized metabolism to oral health and supports the use of BGC-centric analyses to interrogate microbial interactions underlying community stability and disease-associated shifts.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146064296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bio-inspired designer cellulosomes show strongest synergy on industrial substrates under natural-like conditions.","authors":"Babette Lamote, Julie Vanderstraeten, Nette De Ridder, Kenan Meert, Wout Boerjan, Yves Briers","doi":"10.1093/jimb/kuag004","DOIUrl":"10.1093/jimb/kuag004","url":null,"abstract":"<p><p>Designer cellulosomes (DCs) are engineered multienzyme complexes inspired by natural cellulosomes, designed to improve lignocellulose breakdown. Their modular architecture enables the spatial colocalization of diverse catalytic activities, potentially enhancing depolymerization efficiency compared to free enzymes. Although conceptually promising, little is known about how they perform on complex lignocellulosic substrates. In this study, we developed a tetravalent DC using a modular VersaTile assembly approach, incorporating endoglucanase, cellobiohydrolase, β-glucosidase, and endoxylanase activities. The process involved (i) delineating catalytic modules from Cellvibrio japonicus enzymes, (ii) generating docking enzyme variants via combinatorial cloning, and (iii) selecting optimal candidates based on expression, activity, and cohesin-dockerin binding before assembling them onto a scaffoldin with four cohesins and a cellulose-binding module. The resulting DC was tested on two industrially relevant substrates: agro-industrial wheat fibers and genome-edited low-lignin poplar biomass under controlled laboratory conditions. It achieved cellulose-to-glucose conversion yields of 24.98% (150 pmol DC/ml) and 0.82% (200 pmol DC/ml), respectively, under the test conditions. By comparing the saccharification efficiencies of the enzymes in their free and complexed forms, we found that colocalization on a common scaffoldin significantly enhanced synergistic activity. This effect was most pronounced under low enzyme concentrations and when acting on complex lignocellulosic substrates, increasing glucose release compared to free enzymes. These observations highlight that the benefits of colocalization are substrate-dependent and occur under conditions that mimic the natural environment of biomass degradation, conditions that differ from typical industrial settings. This work advances our understanding of DC behavior on real-world substrates, providing essential insights for evaluating their economic viability in industrial applications. One-sentence summary Natural-like conditions helped customized DC release more sugars from biomass than standard industrial setups.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12963819/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146064306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploration of yeast biodiversity from Thai flowers and optimization of carotenoid production by a promising isolate.","authors":"Pirapan Polburee, Thippawan Kodpan, Krittawan Tondee, Nontakorn Wimoolchat","doi":"10.1093/jimb/kuag003","DOIUrl":"10.1093/jimb/kuag003","url":null,"abstract":"<p><p>Microbial synthesis of carotenoids has garnered significant attention as an eco-friendly alternative to conventional synthetic methods and its facile extraction for impressive yield. This study delves into the efficacy of carotenoid production from a red yeast strain, as well as the biodiversity of yeast species from Thai flowers. The research involved the collection of flower samples within Thailand, along with 12 yeast species from 10 genera of Ascomycetes and 4 genera of Basidiomycetes which were isolated by identifying the D1/D2 domain of the large subunit rRNA gene. Unexpectedly, Rhodotorula paludigena SWU-FKT03 emerged as the top performing yeast strain, boasting an impressive carotenoid production rate of 183.30 ± 5.00 mg/L among the 36 red yeast strains isolated. Subsequently, a further investigation was performed, focusing on optimized culture conditions for carotenoid production from this yeast strain. The results were promising, as carotenoid production surged to 288.27 mg/L when 20 g/L of glucose and 10 g/L of monosodium glutamate served as the carbon and nitrogen sources, respectively. These findings underscore the potential of the R. paludigena SWU-FKT03 as a high-yield carotenoid producer when cultivated in shaking flasks, exhibiting a three-fold increase in carotenoid content when under optimized conditions. These results hint at the potential of this approach for future large-scale carotenoid production. One-sentence summary A novel red yeast, Rhodotorula paludigena SWU-FKT03, isolated from Thai floral ecosystems, demonstrated high-yield carotenoid production of 288.27 mg/L after fermentation optimization, establishing a significant potential for industrial applications.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12883991/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145933580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bacterial contamination in starch-to-ethanol fermentations: Can bacteriocin-producing Saccharomyces cerevisiae offer a solution?","authors":"Michelle Rossouw, Bianca J Campbell, Rosemary A Cripwell, Leon M T Dicks, Marinda Viljoen-Bloom","doi":"10.1093/jimb/kuag011","DOIUrl":"10.1093/jimb/kuag011","url":null,"abstract":"<p><p>Increasing interest in the bioeconomy has spurred the development of integrated methods to convert organic waste streams, particularly starch-rich substrates, into bioethanol. However, starch-based ethanol fermentations are vulnerable to bacterial contamination, particularly by lactic acid bacteria (LAB). Severe contamination can cause significant economic losses due to stuck fermentations and ethanol plant shutdowns. Although bacterial contamination can be managed with antibiotics, this approach is not cost-effective at an industrial scale and may increase the risk of selecting for antibiotic-resistant strains. Natural antimicrobial peptides (AMPs) can inhibit LAB contaminants in yeast fermentations, but commercial applications are limited by their low abundance and high production costs. Engineering Saccharomyces cerevisiae to produce recombinant AMPs might provide a cost-effective strategy to control LAB, thereby boosting ethanol yields during fermentation. Despite a comprehensive toolkit for gene expression in S. cerevisiae, only a few successful cases of bacteriocin expression have been reported. Since starch-to-ethanol fermentation is a key application for recombinant AMPs, this review explores strategies to optimize the expression of bacteriocin-encoding genes in S. cerevisiae. The ideal scenario would be a single yeast strain capable of producing amylases for starch hydrolysis, fermenting glucose to ethanol, and expressing bacteriocins to inhibit LAB contaminants. One-sentence summary: Yeast strains can produce heterologous antimicrobial peptides that help prevent contaminating bacteria from interfering with the starch-to-ethanol fermentation process.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13109847/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147662449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical approach for media optimization of fHbp-PorA chimeric protein expression in Escherichia coli; development of a promising Meningococcal B vaccine.","authors":"Annamraju Aswini, Annamraju D Sarma, Sambhaji S Pisal, Selvan Ravindran","doi":"10.1093/jimb/kuag001","DOIUrl":"10.1093/jimb/kuag001","url":null,"abstract":"<p><p>Successful design of an industrial biological product such as a vaccine requires an efficient, robust and reproducible process. In this study, we investigated conditions for process optimization of a promising recombinant factor H binding protein (fHbp)-Porin A (PorA) chimeric protein-based vaccine candidate against Meningococcal B serogroup in Escherichia coli B834 strain using the inducible T7-lac promoter system. Random screening of components of complex culture media for growth and expression using IPTG as an inducer, showed inconsistency when analyzed using Plackett-Burman design (PBD). Further analysis identified galactose present either in tryptone (as lactose) or soy-phytone, has caused strong autoinduction and is surmised as an interfering factor for IPTG induction. Synergistic combination of soy-phytone and yeast extract under conditions of controlled growth and auto-induction gave a good correlation between the cell growth and expression of the fHbp-PorA chimeric protein when evaluated using PBD and central composite design. Using response optimization conditions, an optimized media was attained. A shake flask study was performed to validate the optimized media, and later, a fed-batch fermentation at 10 L scale was established to prove the scalability, consistency, and product quality using the optimized media. One-sentence summary This study reports optimization of cell growth and expression conditions for a recombinant chimeric meningococcal protein in E. coli that assures its industrial scale production and suitability for preclinical and clinical studies as a vaccine component against Meningococcal B serogroup.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12883990/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145933617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complete diploid genome of the type strain Yarrowia lipolytica YB-423 (ATCC 18942™).","authors":"James E Crill, Scott V Nguyen, Corina Tabron, Nikhita Puthuveetil, Anthony Muhle, Zethus W Avery, Joseph Petrone, Kaitlyn Bentley, Jade Kirkland, Noah Wax, Robert Marlow, James Duncan, Steve King, Ana Fernandes, John Bagnoli, Briana Benton, Shahin S Ali, Roy D Welch, Jonathan L Jacobs","doi":"10.1093/jimb/kuag002","DOIUrl":"10.1093/jimb/kuag002","url":null,"abstract":"<p><p>Here, we present the first complete, fully phased diploid genome of type strain Yarrowia lipolytica YB-423 (=ATCC 18942™), constructed using a combination of Oxford Nanopore long-read and Illumina short-read sequencing. Yarrowia lipolytica is an industrially relevant yeast species known for its metabolic versatility, particularly its ability to degrade hydrophobic compounds and express useful products such as fatty acids. Despite its growing use in biotechnology, a high-quality genome assembly of the species' diploid type-strain has been lacking. The assembly and annotations presented here span six chromosomes of paired \"haplotigs\" and a mitochondrial genome, capturing large-scale structural variations and prominent levels of genome-wide heterozygosity. Variant analysis revealed 13,908 heterozygous alleles, of which 3,201 alleles were distributed among 1,237 protein-coding genes. Gene set enrichment analysis showed that these variants are enriched among genes involved in transmembrane transport, suggesting a role in environmental adaptability. Comparative analysis of matched haplotigs for the same chromosome uncovered multiple inversions and transpositions, as well as allele-specific insertions of retrotransposons, providing new insights into the structural complexity and evolutionary dynamics of the genome. The fully phased, finished diploid genome of Y. lipolytica YB-423 represents a crucial step toward unlocking the full genetic potential of Y. lipolytica. Our work will provide a valuable foundation for future comparative and functional genomics and strain engineering studies, particularly for industrial microbiology and biotechnology applications. One-sentence summary This study presents the first fully phased diploid genome of Yarrowia lipolytica type strain YB-423, revealing extensive structural variation and heterozygosity that enhance understanding of its genetic adaptability and industrial potential.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12888388/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145933622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic strategies for high production of Geobacillus stearothermophilus α-amylase in Bacillus subtilis.","authors":"Deming Rao, Changhui Wang, Xiaolin Li, Wei Shen, Qiang Liu, Zerui Li, Shiyu Pi, Zhenggang Han, Jiangke Yang","doi":"10.1093/jimb/kuaf036","DOIUrl":"10.1093/jimb/kuaf036","url":null,"abstract":"<p><p>Although the α-amylase (AmyS) from Geobacillus stearothermophilus exhibits high thermostability, its low enzymatic activity (44.36 ± 2.02 U/mL) severely hinders industrial applications. Given its strong protein secretion capability and GRAS (generally recognized as safe) status, this study employed Bacillus subtilis as the host to enhance AmyS production. Through error-prone PCR and high-throughput screening, a triple mutant T151A/K178E/T458A (AmySM) was generated, showing a 17.67% increase in activity (51.34 ± 1.11 U/mL). AmySM activity was further increased by 29.32% to 65.23 ± 2.33 U/mL using the signal peptide SPykwD, selected from a comprehensive library for superior secretion efficiency. The promoter PgsiB enhanced activity by 37.61% to 89.54 ± 2.95 U/mL. Optimizing the ribosome binding site (RBS) resulted in an additional 48.83% increase in activity, yielding a final activity of 134.02 ± 3.54 U/mL, which corresponds to a 3.02-fold improvement over the initial strain WBSW (44.36 ± 2.02 U/mL). Ultimately, scale-up fermentation in a 5-L bioreactor yielded a maximum extracellular activity of 1244.17 ± 48.66 U/mL at 72 hours, a 2.84-fold increase over the control. This multi-level strategy provides a rational framework for high-efficiency AmySM production, paving the way for extracellular production of high-value proteins in the GRAS host B. subtilis.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12784944/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145794179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Butyric acid production from corn: economics of fermentative production of a novel biobased chemical.","authors":"Nasib Qureshi, Somesh Mishra, Zengshe Liu, Mukti Singh, Ronald E Hector, Thaddeus C Ezeji, Richard D Ashby, Michael A Jackson, Vijay Singh","doi":"10.1093/jimb/kuag009","DOIUrl":"10.1093/jimb/kuag009","url":null,"abstract":"<p><p>In the present study, the economic evaluation of fermentation produced butyric acid (HBu) from corn was carried out (capacity 40 × 103 metric tons HBu∙yr-1) and two recovery processes (distillation and adsorption) were compared. Distillation is a longstanding process that has been effectively used to recover volatile chemicals. Recently, we developed an adsorption process that can be used to recover HBu cost competitively. The direct fixed capital (DFC) of the two processes (distillation & adsorption) were (in US dollars) $73.96 × 106 and $43.91 × 106, respectively. It is reported that the production of HBu from corn requires supplementing with amylase enzymes to the corn mash. For the two processes (distillation & adsorption) the annual operating costs were $37.67 × 106 and $31.83 × 106, respectively. The utilities annual costs for the two processes were $47.38 × 106 and $5.91 × 106, respectively. Corn price is one of the most important factors that influence HBu selling price, but other factors that could lower production costs include plant capacity. Factors such as tax on profit, interest rates on borrowed capital and plant life have marginal or low impact on HBu selling price. The significance of this paper is that HBu produced from corn and recovered by adsorption could be sold for $1.22 to 0.85∙kg-1. The selling price of fermentation produced HBu could further be reduced considerably if agricultural biomass such as wheat straw is used for production. One sentence summary Butyric acid production by fermentation and process economics.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13070389/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147443780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Innovations in process engineering approaches for enhanced bacteriocin production.","authors":"Joan Sweetlin Shanmugam, Sreeja Shanmuga Doss","doi":"10.1093/jimb/kuag010","DOIUrl":"10.1093/jimb/kuag010","url":null,"abstract":"<p><p>Bacteriocins are ribosomally synthesized antimicrobial peptides produced by various classes of bacteria, exhibiting broad-spectrum activity that makes them promising candidates for applications in food preservation and medicine. Their inherent stability under extreme pH, temperature, and salinity conditions further supports their functional versatility. However, the widespread industrial application of bacteriocins remains constrained by the low titres typically achieved during fermentation. Despite extensive efforts to optimize production using batch and fed-batch fermentation strategies, the resulting titres remain inadequate for economically viable large-scale manufacturing. This review aims to provide a comprehensive overview of novel process strategies developed over the past two decades to enhance bacteriocin yields during fermentation. One of the primary challenges is the inhibition of microbial growth due to the accumulation of lactic acid or the bacteriocin itself during production. To address this, in situ product removal techniques-such as co-cultivation with lactic acid-consuming microorganisms, in situ adsorption, filtration, and foam fractionation-have been explored, yielding notable improvements in bacteriocin titres. Additionally, stress-induced production strategies involving biological (e.g., co-culture with competing microbes), chemical (e.g., salinity and pH stress), and physical (e.g., agitation, temperature, and aeration stress) stimuli have also demonstrated success in enhancing bacteriocin synthesis. This review underscores the importance of these innovative fermentation approaches and highlights the need for further research focused on scaling up such processes. Advancing these strategies is critical to realizing the full potential of bacteriocins in food safety, antimicrobial therapy, and broader biomedical applications. One-sentence summary This review provides a comprehensive view of the novel fermentation strategies developed in the last two decades to overcome low bacteriocin titres during fermentation such as in situ lactate removal, in situ bacteriocin removal, and stress-led induction.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13037702/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147468193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Protoplast fusion as a strategy to increase ploidy in Rhodotorula toruloides for strain development.","authors":"Daiane D Lopes, Bruce S Dien, Ronald E Hector, Stephanie R Thompson, Vijay Singh, Sujit S Jagtap, Nancy N Nichols, Christopher V Rao, Christopher Skory, Patricia J Slininger","doi":"10.1093/jimb/kuaf037","DOIUrl":"10.1093/jimb/kuaf037","url":null,"abstract":"<p><p>Rhodotorula toruloides is a red oleaginous yeast with growing commercial interest because of its hardiness and exceptional lipid production capacity. Because it is a basidiomycete yeast with a complex life cycle, many of the classical breeding methods used with ascomycetes are unavailable for strain improvement. However, we have been able to construct polyploid yeast by fusing protoplasts of parents with the same mating type. Fusing of Y-6985 (A2) and Y-48190 (A2), which had been transformed with complementary antibiotic markers, led to the recovery of two diploids and one triploid. The stability of the fusion yeasts was tested by plating them on non-selective medium after several growth cycles under antibiotics and then testing five colonies per strain for nuclear DNA contents using flow cytometry and standard cell cycle analysis: the triploid and one diploid were stable. Fusants inherited their mitochondria from a single parent, which was demonstrated using restriction fragment length polymorphism (RFLP) of mitochondrial DNA. The phenotypic properties of the parents and fusants were compared in glucose fed-batch bioreactor studies and cellulosic sugar batch cultures. The final lipid titers for the fed-batch cultures were 24.9-39.7 g/L with Y-6985 and the diploid and triploid performing the best and worst, respectively. The fusants demonstrated intermediate hardiness for growth on hydrolysate prepared with dilute-acid pretreated switchgrass and were outperformed by Y-48190. Unlike one of the haploid parents, the fusants grew in 70% v/v concentrated hydrolysate. However, they did not grow as fast as the other haploid. In this study, a modernized protoplast fusion method is resurrected a useful tool for strain development in this yeast, which is complementary with other available methods.</p>","PeriodicalId":16092,"journal":{"name":"Journal of Industrial Microbiology & Biotechnology","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12781891/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145708066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}