During an investigation of indigenous prokaryotic species in the Republic of Korea, 17 bacterial strains belonging to the phylum Bacteroidota and 4 strains belonging to the phylum Bacillota were isolated from freshwater environments. These isolated bacterial strains formed a robust phylogenetic clade with type strains of the closest related bacterial species, with 16S rRNA gene sequences sharing similarities of higher than 98.7%. To date, there have been no official report of these 21 isolates in the Republic of Korea. At the genus level, these unreported species were affiliated with Mucilaginibacter and Pedobacter of class Sphingobacteriia, Flavobacterium and Gillisia of class Flavobacteriia, Hymenobacter of class Cytophagia, and Paenibacillus and Planococcus of class Bacilli. These species were further examined by performing Gram staining, analyzing their colonies and cell morphologies, and determining their basic biochemical characteristics and phylogenetic positions. Detailed descriptions of the 21 previously unreported species are provided.

A new spider species of the genus Pholcus Walckenaer, 1805, Pholcus osaek sp. nov., in the family Pholcidae C.L. Koch, 1850, is described from Korea. This new species belongs to phungiformes-group in the genus. It can be distinguished from its congeners by the shape and structure of genital organs of both males and females. It is found on and between rock walls in mountainous mixed forests. Additionally, the taxonomic status of Pholcus uksuensis Kim & Ye, 2014 is revalidated, re-diagnosed, and redescribed based on specimens collected from the type locality. Considering differences mentioned in the diagnosis through revalidation, P. uksuensis is regarded as a distinct species. Therefore, it should be removed from the synonymy of P. woongil Huber, 2011.

Freshwater environments serve as crucial habitats for diverse microorganisms, playing essential roles alongside plants and animals within the ecosystem. Bacteria in these environments are particularly important for maintaining ecosystem functions. Among them, members of the phylum Pseudomonadota are known to be involved in processes such as nitrogen fixation, ammonia oxidation, and biofilm formation. Pseudomonadota comprises six classes: Acidithiobacillia, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Hydrogenophilia, and Zetaproteobacteria. This study reports 43 previously unrecorded species belonging to the phylum Pseudomonadota. They were isolated from various freshwater habitats in Republic of Korea. These strains were isolated and cultured using nine different standard media, with classification based on Gram staining, cell morphology, and biochemical characteristics. Species identity was determined using 16S rRNA gene sequencing, with a similarity threshold of 98.7% for designation as unreported species. Phylogenetic analysis revealed that these 43 strains were distributed across three classes, 13 orders, 28 families, and 39 genera. This research emphasizes microbial diversity in freshwater ecosystems and provides valuable insights into ecological roles and potential novel functions of unreported bacterial species in Korea.

As part of the 2024 research initiative, “Investigation and Discovery of Prokaryotes in Freshwater Systems,” samples were collected from diverse freshwater habitats, including both water and soil environments. Approximately 2,000 bacterial strains were isolated as single colonies and identified through 16S rRNA gene sequence analysis. Among these, 38 strains shared ≥98.7% 16S rRNA gene sequence similarities with those of known bacterial species not previously reported in Korea. These strains were thus categorized as newly recorded bacterial species in Korea. These 38 bacterial strains displayed significant phylogenetic diversities, spanning 2 phyla, 4 classes, 15 orders, 24 families, and 34 genera. These unrecorded species were classified into the following classes: Actinomycetia (with genera including Microcella, Conyzicola, Curtobacterium, Leucobacter, Microbacterium, Frigoribacterium, Lysinibacter, Streptomyces, Nonomuraea, Actinocorallia, Ruania, and Actinoplanes), Alphaproteobacteria (Paracoccus, Youngimonas, Loktanella, Corticibacterium, Neorhizobium, Onobrychidicola, Ferranicluibacter, Aureimonas, Asticcacaulis, and Novosphingobium), Betaproteobacteria (Rhodoferax, Rugamonas, and Cupriavidus), and Gammaproteobacteria (Rheinheimera, Shewanella, Kosakonia, Leclercia, Hafnia, Yersinia, Pseudomonas, Lysobacter, and Acinetobacter ). Further characterization included assessment of Gram reaction, colony and cell morphology, biochemical properties, and phylogenetic relationships. This report presents detailed phylogenetic and phenotypic characteristics of these bacterial species.

LIn this study, we investigated the habitat characteristics of a Jeonju Duckjin lake in Jeonju City, Jeonbuk, in which a large group of reeve’s turtle(Mauremys reevesii)(endangered species Class II and natural monument No. 453 in Korea) was discovered. The lake where reeve’s turtle(M. reevesii) was discovered, was beside Jeonbuk National university. That lake was surrounded by lotuses, dam, and reeds. We found 12 reeve’s turtle(M. reevesii)(included with 2 juveniles), 30 red eared slider (Trachemys scripta elegans)(included with 4 juveniles), 22 river cooter(Pseudemys concinna)(included with 5 juveniles), and 6 Chinese stripe necked turtle(Mauremys sinensis)(included with 4 juveniles) from June to September, 2024, respectively. A number of red-eared sliders(Trachemys scripta elegans) which threaten the survival of reeve’s turtle(M. reevesii), were also found in and around the lake. Newborn turtles in this year were not observed. However, we estimated that natural breeding had sufficiently occurred since we observed many young turtles in the lake. Furthermore, the presence of young red-eared slider individuals can be a persistent problem for reeve’s turtle(M. reevesii) as they are competing species. In conclusion, in-situ conservation method should be considered for protecting the endangered turtle and their habitat.