Heme, an iron-incorporated porphyrin compound, serves as the prosthetic group for numerous proteins involved in diverse biological processes. The prokaryotic heme biosynthetic pathway features a complex cascade of reactions, in which glutamyl-tRNA reductase (GluTR) catalyzes the formation of 5-aminolevulinic acid (ALA) that represents a critical rate-limiting step and determines ultimate heme yield. In this study, OsGluTRA510V showed enhanced heme synthesis capacity in Oryza sativa and was used for developing microbial cell factories dedicated to free heme production. Through systematic protein engineering involving site-directed mutagenesis and N-terminal modification, OsGluTRA510V was optimized to improve the structural stability and catalytic efficiency. It yielded the recombinant enzyme GluTRA510V/S189T/KK, which achieved a maximum heme titer of 13.14mg/L in Escherichia coli, representing a 7.6-fold improvement over that of GluTRA510V. To establish heme production in Bacillus subtilis, GluTRA510V/S189T/KK was introduced into the ΔhmoAB-hemX chassis, a modified B. subtilis host lacking key heme biosynthesis inhibitors (hmoA, hmoB, and hemX). This engineered system elevated the heme yield from 0.77 to 3.86mg/L, achieving a 5.0-fold improvement. This study demonstrates a combinatory metabolic engineering strategy that reconstitutes the heme synthetic route in B. subtilis, enabling efficient production of food-grade free heme through enzyme engineering and chassis optimization.

The aim of this study was to produce fungal chitosan from a potential fungus using a cost-effective substrate (sugar beet molasses) and optimize the growth conditions using Taguchi L9 orthogonal array (OA). The obtained fungal chitinous chitosan (FC) was then used for the microencapsulation of crocin. Optimal conditions were found as 120mL/L molasses, initial pH at 6 and 5g/L magnesium sulphate. The dried biomass was weighed as 22.7g/L, while 8.1g/L alkali insoluble material (AIM), 5.3g/L FC and 2.7g/L native chitosan (NC) were obtained. Deacetylation degree (DD) of the obtained chitosan was calculated as 80.27 and 78.81% for NC and FC, respectively. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) was employed for molecular weight detection of the chitosan samples. Molecular weights were found for FC and commercial chitosan (CC) as 145 and 219kDa, respectively. The solubility of NC and FC in 1% acetic acid was found as 84 and 78% respectively. The fungus was isolated from jujube fruit which was identified as Penicillium expansum HNP11 (GenBank Accession Number: PQ057454). To deepen the research, antimicrobial activity was carried out. The zeta potential of crocin loaded alginate-chitosan microparticles was about - 49mV and loading capacity was found as 46%. Cytotoxicity of FC was found lower than CC at low concentrations. Consequently, P. expansum has higher antimicrobial activity and minimal toxic structure and Taguchi orthogonal array contributes economic chitosan production.

d-Glucosaminic acid is a valuable amino acid useful in food and medical applications. It is a highly sought after enantiopure molecule important for the synthesis of drugs and glycopeptides. Current enzymatic synthesis pathways to d-glucosaminic acid carry disadvantages such as low product yield and long reaction times. Herein, the Auxiliary Activity 7 chito-oligosaccharide oxidase from Lentinus brumalis, LbChi7A, was shown as a potent biocatalyst capable of efficiently converting d-glucosamine (GlcN) and N-acetyl-d-glucosamine (GlcNAc) to their respective C1-acids. The substrate specificity of LbChi7A towards GlcN and GlcNAc enabled the conversion of at least 90% GlcN to d-glucosaminic acid and 100% GlcNAc to N-acetyl-d-glucosaminic acid within 60 min. LbChi7A inhibition by the hydrogen peroxide co-product was not detected, even at 860 mM. This single enzymatic conversion offers a clean and efficient process to produce industrially relevant glucosaminic acids, including d-glucosaminic acid and N-acetyl-d-glucosaminic acid.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10529-026-03721-9.

To investigate the effects of fungal volatile organic compounds (FVOCs) on the mycelial growth of Ganoderma lucidum, and to elucidate the molecular mechanisms underlying the growth-promoting effect of 3-octanone. G. lucidum was cultivated with 1-octen-3-ol, 3-octanol and 3-octanone for 7 days, after which colony diameter and mycelial dry weight were measured to assess their effects on mycelial growth. RNA-seq was used to investigate gene expression changes following 3-octanone exposure. While 1-octen-3-ol or 3-octanol inhibited mycelial growth in G. lucidum, 3-octanone promoted it. In total, 590 differentially expressed genes (DEGs), including 162 upregulated and 428 downregulated genes, were identified following 3-octanone exposure. Functional annotation revealed that among the DEGs, 23 genes were related to fungal cell wall biosynthesis and remodeling, whereas 21 genes were involved in plant-derived polysaccharide degradation. Furthermore, significant expression changes were observed in genes related to secondary metabolism. Our results indicate that G. lucidum can use 3-octanone as a signal to recognize other fungi, potentially facilitating the expansion of its own territory within wood in nature.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10529-026-03698-5.

Polyunsaturated fatty acids (PUFAs) have attracted significant attention for their roles in human health, particularly in cardiovascular protection. As a promising source of PUFAs, microalgae have become a research hotspot due to their rapid growth and ability to accumulate large amounts of PUFAs under stress conditions. This paper reviewed the recent progress in microalgal PUFAs research, focusing on analyzing PUFA content in different microalgal species, the effects of environmental factors on PUFAs synthesis, as well as related biochemical pathways. Additionally, this paper explored strategies for enhancing PUFA production in microalgae using metabolic engineering and gene editing, and outlined current research challenges.

In this study, medlar polyphenol oxidase (PPO) was partially purified by (NH4)2SO4 precipitation and dialysis, respectively. The aim of the study was to investigate the inhibition effects of amino acids, which are candidate PPO ligands, on the activity of the medlar PPO enzyme for advanced biochemical purification techniques and to create a usage field for the enzyme inhibitors in different industrial sectors. No any inhibition studies of amino acids have been investigated on medlar PPO in literature yet. Inactivation of PPO is preferred to be prevention of decreasing of nutritional quality and shelf life of foods. Two bands were determined in electrophoresis analyses. Following, amino acids effects were studied on medlar PPO activity to investigate the potentials of Glycine (Gly), L-Phenylalanine (L-Phe), L-Tyrosine (L-Tyr), L-Cysteine (L-Cys), L-Serine (L-Ser), L-Aspartic acid (L-Asp), L-Histidine (L-His), L-Lysine (L-Lys), L-Proline (L-Pro), and L-Methionine (L-Met) whether acting as natural PPO inhibitors. Inhibition types were determined for catechol and L-Cys was found as a potent competitive inhibitor of medlar PPO. While Gly, L-Phe, L-Pro, L-Ser, L-His, and L-Lys showed uncompetitive inhibition; L-Tyr, L-Asp, and L-Met showed mixed-type inhibition. Statistical analysis was performed to understand whether the chemical structure or concentration of inhibitors showing the same type of inhibition made a statistically significant difference on the enzyme activity %. The results showed that the structure of inhibitors did not make a statistically significant difference on the enzyme activity % while inhibitor concentration created significant difference.

Yeast plays a pivotal role in beer brewing, as its metabolic activity directly determines the flavor profile, product quality, and production efficiency of beer. With the rapid advancement of biotechnology, innovative techniques such as omics, adaptive evolution, and CRISPR-based genome editing have significantly accelerated the process of yeast strain breeding. These technologies not only enhance fermentation performance but also enable the targeted development of novel strains with specific phenotypic traits, thereby addressing diverse market demands for customized beer characteristics. This review systematically discusses current strategies for beer yeast breeding, with particular emphasis on recent technological breakthroughs in strain development. Furthermore, we provide insights into future trends in strain enhancement technologies, highlighting the importance of multidimensional strategies, high-throughput selection platforms, the synergistic integration of synthetic biology and computational modeling to achieve precise strain optimization. This review highlights that continuous technological innovation is crucial for enhancing yeast breeding efficiency and meeting the evolving demands of the industry.

D-Asp is a pharmaceutically valuable amino acid used as an antibiotic precursor and has potential therapeutic benefits for neurological disorders and reproductive health. The lactic acid bacterium Latilactobacillus curvatus strain WDN19, originally isolated from a salt-fermented pickle, produces large amounts of D-Asp from L-Asp. To optimize D-Asp production, we investigated the effects of various cultivation conditions. Growth and D-Asp formation increased concomitantly with temperature, reaching a maximum at 37°C, whereas no growth occurred at 40°C. L-Asp concentrations ≤ 100mM minimally affected biomass, yet higher levels curtailed both growth and conversion, revealing an intrinsic racemization capacity of ~ 30mM under unbuffered conditions. Strain WDN19 grew across an initial pH range of 5.0-9.5, but rapid acidification to pH ≈ 4.5 triggered severe cell death and arrested D-Asp synthesis. Incorporation of 500mM 2-morpholinoethanesulfonic acid maintained near-neutral pH, preserved viability, and enabled almost quantitative racemization of up to 500mM L-Asp within 48h, yielding > 250mM D-Asp. These findings establish pH control as the critical determinant for high-yield D-Asp production by strain WDN19, providing a practical framework for environmentally friendly, fermentation-based manufacturing of this pharmaceutically valuable amino acid.