Discovery of Spirosnuolides A-D, Type I/III Hybrid Polyketide Spiro-Macrolides for a Chemotherapeutic Lead against Lung Cancer.

Four new macrolides, spirosnuolides A-D (-, respectively), were discovered from the termite nest-derived sp. INHA29. Spirosnuolides A-D are 18-membered macrolides sharing an embedded [6,6]-spiroketal functionality inside the macrocycle and are conjugated with structurally uncommon side chains featuring cyclopentenone, 1,4-benzoquinone, hydroxyfuroic acid, or butenolide moieties.

Flavobacterium rivulicola sp. nov., Isolated from a Freshwater Stream.

A Gram-strain-negative, aerobic, yellow-colored, non-motile, and rod-shaped bacterial strain, designated IMCC34852, was isolated from a freshwater stream in the Republic of Korea. Cellular growth occurred at 10-37 °C, pH 6.0-9.

Discovery of Terminal Oxazole-Bearing Natural Products by a Targeted Metabologenomic Approach.

A targeted metabologenomic method was developed to selectively discover terminal oxazole-bearing natural products from bacteria. For this, genes encoding oxazole cyclase, a key enzyme in terminal oxazole biosynthesis, were chosen as the genomic signature to screen bacterial strains that may produce oxazole-bearing compounds. Sixteen strains were identified from the screening of a bacterial DNA library (1,000 strains) using oxazole cyclase gene-targeting polymerase chain reaction (PCR) primers.

Metagenome sequencing and recovery of 444 metagenome-assembled genomes from the biofloc aquaculture system.

Biofloc technology is increasingly recognised as a sustainable aquaculture method. In this technique, bioflocs are generated as microbial aggregates that play pivotal roles in assimilating toxic nitrogenous substances, thereby ensuring high water quality. Despite the crucial roles of the floc-associated bacterial (FAB) community in pathogen control and animal health, earlier microbiota studies have primarily relied on the metataxonomic approaches.

Metagenomic data from surface seawater of the east coast of South Korea.

The East Sea, also known as the Sea of Japan, is a marginal sea located in the western Pacific Ocean, displaying comparable characteristics to Earth's oceans, thereby meriting its recognition as a "miniature ocean". The East Sea exhibits a range of annually-recurring biogeochemical features in accordance with seasonal fluctuations, such as phytoplankton blooms during the spring and autumn seasons. Despite ongoing monitoring efforts focused on water quality and physicochemical parameters, the investigation of prokaryotic assemblages in the East Sea, encompassing seasonal variations, has been infrequently pursued.

Targeted and Logical Discovery of Piperazic Acid-Bearing Natural Products Based on Genomic and Spectroscopic Signatures.

A targeted and logical discovery method was devised for natural products containing piperazic acid (Piz), which is biosynthesized from ornithine by l-ornithine -hydroxylase (KtzI) and - bond formation enzyme (KtzT). Genomic signature-based screening of a bacterial DNA library (2020 strains) using polymerase chain reaction (PCR) primers targeting identified 62 strains (3.1%).

Proposal of Flavihumibacter fluvii sp. nov. as a replacement name for the effectively published but invalidated epithet Flavihumibacter fluminis Park et al. 2022.

The name Flavihumibacter fluminis Park et al. 2022, which was effectively published but invalidated, is an illegitimate homonymic epithet of Flavihumibacter fluminis Guo et al. 2023.

Metabolic Versatility of the Family Revealed by the Genomics of Novel Cultured Isolates.

The family (OM60/NOR5 clade) is a gammaproteobacterial group abundant and cosmopolitan in coastal seawaters and plays an important role in response to phytoplankton blooms. However, the ecophysiology of this family remains understudied because of the vast gap between phylogenetic diversity and cultured representatives. Here, using six pure cultured strains isolated from coastal seawaters, we performed in-depth genomic analyses to provide an overview of the phylogeny and metabolic capabilities of this family.

sp. nov., isolated from a lotus wetland.

A Gram-stain-negative, aerobic, rod-shaped and motile bacterium, designated IMCC34681, was isolated from a lotus wetland in the Republic of Korea. Cellular growth occurred at 10-37 °C (optimum, 30 °C), pH 6-9 (optimum, pH 7) and with 0-2 % (w/v) NaCl (optimum, 0.5 % NaCl).

Exploring bacterioplankton communities and their temporal dynamics in the rearing water of a biofloc-based shrimp () aquaculture system.

Biofloc technology (BFT) has recently gained considerable attention as a sustainable method in shrimp aquaculture. In a successful BFT system, microbial communities are considered a crucial component in their ability to both improve water quality and control microbial pathogens. Yet, bacterioplankton diversity in rearing water and how bacterioplankton community composition changes with shrimp growth are rarely documented.

Flavihumibacter fluminis sp. nov. and Flavihumibacter rivuli sp. nov., isolated from a freshwater stream.

Two Gram-stain-positive, aerobic, chemoheterotrophic, non-motile, rod-shaped, and yellow-pigmented bacterial strains, designated IMCC34837 and IMCC34838, were isolated from a freshwater stream. Results of 16S rRNA gene-based phylogenetic analyses showed that strains IMCC34837 and IMCC34838 shared 96.3% sequence similarity and were most closely related to Flavihumibacter profundi Chu64-6-1 (99.

Epoxinnamide: An Epoxy Cinnamoyl-Containing Nonribosomal Peptide from an Intertidal Mudflat-Derived sp.

Cinnamoyl-containing nonribosomal peptides (CCNPs) form a unique family of actinobacterial secondary metabolites and display various biological activities. A new CCNP named epoxinnamide () was discovered from intertidal mudflat-derived sp. OID44.

Taeanamides A and B, Nonribosomal Lipo-Decapeptides Isolated from an Intertidal-Mudflat-Derived sp.

Two new lipo-decapeptides, namely taeanamides A and B ( and ), were discovered from the Gram-positive bacterium sp. AMD43, which was isolated from a mudflat sample from Anmyeondo, Korea. The exact molecular masses of and were revealed by high-resolution mass spectrometry, and the planar structures of and were elucidated using NMR spectroscopy.

Heme auxotrophy in abundant aquatic microbial lineages.

Heme, a porphyrin ring complexed with iron, is a metalloprosthetic group of numerous proteins involved in diverse metabolic and respiratory processes across all domains of life, and is thus considered essential for respiring organisms. Several microbial groups are known to lack the de novo heme biosynthetic pathway and therefore require exogenous heme from the environment. These heme auxotroph groups are largely limited to pathogens, symbionts, or microorganisms living in nutrient-replete conditions, whereas the complete absence of heme biosynthesis is extremely rare in free-living organisms.

A sulfate-reducing bacterial genus, Desulfosediminicola gen. nov., comprising two novel species cultivated from tidal-flat sediments.

Tidal-flat sediments harbor a diverse array of sulfate-reducing bacteria. To isolate novel sulfate-reducing bacteria and determine their abundance, a tidal-flat sediment sample collected off Ganghwa Island (Korea) was investigated using cultivation-based and culture-independent approaches. Two Gram-stain-negative, strictly anaerobic, rod-shaped, sulfate-reducing bacteria, designated IMCC35004 and IMCC35005, were isolated from the sample.

Cultivation of Dominant Freshwater Bacterioplankton Lineages Using a High-Throughput Dilution-to-Extinction Culturing Approach Over a 1-Year Period.

Although many culture-independent molecular analyses have elucidated a great diversity of freshwater bacterioplankton, the ecophysiological characteristics of several abundant freshwater bacterial groups are largely unknown due to the scarcity of cultured representatives. Therefore, a high-throughput dilution-to-extinction culturing (HTC) approach was implemented herein to enable the culture of these bacterioplankton lineages using water samples collected at various seasons and depths from Lake Soyang, an oligotrophic reservoir located in South Korea. Some predominant freshwater bacteria have been isolated from Lake Soyang via HTC (e.

Uliginosibacterium aquaticum sp. nov., Isolated from a Freshwater Lake.

A Gram-stain-negative, aerobic, chemoheterotrophic, rod-shaped bacterium motile by a polar flagellum, designated IMCC34675, was isolated from Chungju Lake, an artificial freshwater reservoir in Republic of Korea. The 16S rRNA gene sequence analysis indicated that strain IMCC34675 belongs to the genus Uliginosibacterium, sharing ≤ 97.1% sequence similarities with the type strains of the genus.

sp. nov., isolated from a freshwater stream.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated as IMCC34836, was isolated from a freshwater stream. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain IMCC34836 was most closely related to HW001 (of the family ) with 95.6 % sequence similarity and formed a robust clade with HW001.

High-throughput cultivation based on dilution-to-extinction with catalase supplementation and a case study of cultivating acI bacteria from Lake Soyang.

Multi-omics approaches, including metagenomics and single-cell amplified genomics, have revolutionized our understanding of the hidden diversity and function of microbes in nature. Even in the omics age, cultivation is an essential discipline in microbial ecology since microbial cultures are necessary to assess the validity of an in silico prediction about the microbial metabolism and to isolate viruses infecting bacteria and archaea. However, the ecophysiological characteristics of predominant freshwater bacterial lineages remain largely unknown due to the scarcity of cultured representatives.

Viral metagenomes of Lake Soyang, the largest freshwater lake in South Korea.

A high number of viral metagenomes have revealed countless genomes of putative bacteriophages that have not yet been identified due to limitations in bacteriophage cultures. However, most virome studies have been focused on marine or gut environments, thereby leaving the viral community structure of freshwater lakes unclear. Because the lakes located around the globe have independent ecosystems with unique characteristics, viral community structures are also distinctive but comparable.