National Institute of Biological Resources

Valeriana fauriei and V. dageletiana are traditional medicinal plants known for their calming effects and use in alleviating insomnia. However, genomic information for these species is limited. This study aimed to sequence and characterize the complete chloroplast genomes of V. fauriei and V. dageletiana, and to compare them with those of closely related Valeriana species to investigate structural variation, molecular evolution, and divergence history. The chloroplast genomes of V. fauriei, V. dageletiana, and V. jatamansi were highly conserved in overall structure. Minor differences were observed in tandem repeat regions and sequence divergence hotspots, particularly within accD, rps18, and the trnN–trnL intergenic region. Analysis of 57 protein-coding genes from four species revealed that most genes are under strong purifying selection. However, elevated dN/dS ratios in psbI, rps7, and rpl23 suggest potential lineage-specific divergence. Phylogenetic reconstruction showed that V. fauriei and V. dageletiana form a clade with V. officinalis, whereas V. jatamansi is an earlier diverging lineage. Divergence time estimation indicated that V. officinalis split from this clade 0.4255 to 1,0839 million years ago, and that V. fauriei and V. dageletiana diverged approximately 0.0205 million years ago. These results provide insights into the evolution of Valeriana chloroplast genomes, highlighting both structural conservation and species-specific variation. The findings contribute to a better understanding of recent speciation events and molecular evolution in this genus, supporting future phylogenomic and taxonomic studies of Valeriana species.

Halophilic archaea are extremophilic microorganisms uniquely adapted to thrive in hypersaline environments such as solar salterns, saline lakes, and brines. Their ability to survive under high-salt conditions is closely associated with the production of unique compounds specifically synthesized by haloarchaea, including bacterioruberin and halorhodopsin. Bacterioruberin is a carotenoid pigment that protects cells from oxidative stress and contributes to osmotic stress resistance. Halorhodopsin is a light-driven Cl- pump that helps maintain ionic homeostasis. These functional molecules play crucial roles in osmotic stress resistance and energy conversion under extreme conditions. Therefore, understanding their genomic information is essential to uncover the molecular mechanisms underlying their remarkable adaptation and survival in high-salt conditions. In this study, we performed genomic analysis of 12 strains of haloarchaea isolated from Korean solar salterns. Phylogenetic and whole-genome analysis revealed that the isolates are taxonomically distinct from closely related species. The core genes (crtE, crtB, crtI, lyeJ, crtD, and cruF) for bacterioruberin biosynthesis were generally conserved across all analyzed strains, but some strains were found not to possess the crtI gene, and halorhodopsin gene (hop) was identified only in 7 strains. These results show the diversity and conservation of gene distribution related to adaptation to a high-salt environment. As a result, the compensatory role of crtD in the strain lacking the crtI and the lack of the hop in the genus Haloferax were confirmed. These results expand the understanding of the genetic and evolutionary basis associated with adaptation to high-salt environments.

To infer the hitchhiking routes of the invasive ragweed leaf beetle Ophraella communa LeSage in domestic areas of the Korean Peninsula, we analyzed the genetic structure and demographic history of the species collected from 12 domestic areas leveraging mitochondrial DNA sequence (MT data) and microsatellite loci genotype (MS data). Based on MT data analysis results, 440 individuals from 12 domestic areas were analyzed and divided into a total of 31 haplotypes, with a sequence distance of 0–3.3%. Haplotype network analysis identified two high-frequency haplotypes linked via eight median vectors. Therefore, we considered that O. communa had at least two different invasive routes into the domestic areas of the Korean Peninsula. MS data indicated that the species had three invasive routes into the Korean Peninsula and was divided into three groups. The ad hoc statistic Δ(K) confirmed three clusters, and individual bar plot analysis of the invaded populations revealed three distinct genetic compositions. MT and MS data results differed in the number of invading populations considered. These differences were suggested to stem from resolution variations due to the founder effect. In conclusion, at least two O. communa populations may invade several international ports of the Korean Peninsula and spread domestically via hitchhiking on transport, such as container-carrying tractors. Individuals spread by transportation may disperse into local areas due to the behavioral traits of O. communa, such as being strongly attracted to the host plant Ambrosia artemisiifolia. We anticipate that our findings will help pinpoint critical areas for preventing the inland spread of invasive species.

Diazinon is a widely used organophosphate insecticide that persists in agricultural runoff and poses risks to aquatic ecosystems and public health.In this study, we investigated the potential of a genetically engineered cyanobacterium, Synechocystis sp.PCC 6803, for efficient diazinon removal under varying environmental conditions.A phoU mutant lacking the negative regulator of the Pho regulon was employed to maintain constitutive phosphate uptake and metabolism independent of external phosphate availability.The phoU strain exhibited sustained expression of alkaline phosphatase (ALP), resulting in ALP activity 2.5-fold higher than that of the wild-type (WT).Under different phosphate concentrations (0-1.6 mM), phoU completely degraded diazinon (20 mg/l) within 11 days, with a degradation rate constant (k) up to 2.1-fold higher than WT under phosphate-replete conditions.Concurrently, phoU accumulated intracellular polyphosphate (poly-P) at levels up to four times higher than WT.Light intensity further modulated diazinon degradation and phosphate metabolism.Under high light intensity (2000 mol photons/m 2 /s), the phoU strain showed a 2.5-fold increase in diazinon degradation rate compared to WT, accompanied by a maximum poly-P accumulation of 10.95 mg/g FCW.Correlation analysis revealed a strong positive relationship between degradation rate and poly-P accumulation, indicating that organophosphate pesticide degradation is functionally linked to intracellular phosphate metabolism.These findings demonstrate that genetic deregulation of the Pho regulon enhances both diazinon degradation and phosphate assimilation, highlighting the phoU mutant as an effective cyanobacterial platform for organophosphate pesticide bioremediation under environmentally relevant conditions.

Microalgae have emerged as a promising and sustainable platform for the production of omega-3 polyunsaturated fatty acids, offering an alternative to fish-derived sources. Among these, Microchloropsis salina (formerly Nannochloropsis salina) is particularly attractive as a candidate due to its naturally high eicosapentaenoic acid (EPA) content. In this study, bacterial supernatants from various myxobacterial strains were evaluated for their ability to enhance microalgal growth and EPA production. Remarkably, the supernatant derived from Nannocystis sp. KYC 2844 significantly improved biomass accumulation when added at 20% (v/v) to f/2 medium, increasing dry cell weight from 1.69 g/l (control) to 2.13 g/l. Although total lipid content decreased from 25.1% to 13.0%, the EPA fraction within the lipid markedly increased from 9.46% to 27.2%. As a result, the overall EPA titer reached 75.5 mg/l, representing a 1.87-fold improvement over the control. Subsequent nutrient analysis revealed that the KYC 2844 supernatant contained 127.3 ppm of ammonium (NH4+), which served as a preferred nitrogen source for M. salina and delayed nitrate utilization. These findings indicate that nitrogen speciation plays a critical role in shaping microalgal lipid profiles. Collectively, this study demonstrates that microbial supernatants can serve as effective medium supplements to enhance both growth and EPA productivity in microalgae and offers a potential strategy for improving the efficiency of microalgal-based omega-3 production systems.

Microbial inoculation is a commonly applied approach in composting to enhance organic matter biodegradation and reduce odor emissions. However, the different characteristics of bacteria in terms of temperature can be considered to optimize their effect during different phases of composting. A mesophilic bacterium, namely Aquamicrobium lusatiense NLF 2-7, was evaluated to mitigate odor emissions and enhance the bacterial community under mesophilic composting. Two different treatments were designed: treatment 1 with a single inoculation on the initial day and treatment 2 with split inoculation at the initial and after 2weeks. Results show that the treatments improve organic matter decomposition by 17.7-28.6% and significantly reduce volatile sulfur compound emissions, especially dimethyl sulfide (DMS) and hydrogen sulfide (H2S) during the initial phase of composting. DMS emissions were mostly emitted in the first week, with reduction rates of 60.3% and 61.5% in both treatments, respectively. Additionally, mean phenol emissions were reduced by 7.9% in treatment 1 and 11.7% in treatment 2. The dominant bacterial phyla during composting were Bacillota, Pseudomonadota, Bacteroidota, and Actinomycetota, comprising 74 to 95% of the total population. This experiment suggests that A. lusatiense NLF 2-7, which is known for reducing sulfur emissions, can also enhance organic matter decomposition. Split inoculation appears more beneficial, with an initial inoculation managing sulfur emissions early on, followed by a second inoculation after the thermophilic phase to control phenol emissions throughout the composting process.