Bacteroides faecium sp. nov. isolated from human faeces.

A novel bacterial strain, CBA7301T, was isolated from human faeces and was characterised using a polyphasic taxonomic approach. A phylogenetic analysis based on 16S rRNA gene sequences revealed that CBA7301T represented a member of the genus Bacteroides, in the family Bacteroidaceae. The similarity between the 16S rRNA gene sequence of CBA7301T and that of its most closely related species, Bacteroides faecichinchillae JCM 17102T, was 96.2 %, and the average nucleotide identity between these two strains was 77.9 %. The genome size was 6 782 182 bp, and the DNA G+C content was 42.5 mol%. Cells of CBA7301T were Gram-stain-negative, strictly anaerobic and rod-shaped. The optimal growth of this organism occurred at 30-35 °C, pH 7.0 and 0.5 % (w/v) NaCl. The respiratory quinone was menaquinone 10. The predominant polar lipids were phosphatidylethanolamine, phospholipids and aminophospholipids. The major cellular fatty acid was anteiso-C15 : 0. According to the results of the polyphasic taxonomic analysis, CBA7301T represents a novel species of the genus Bacteroides, which we named Bacteroides faecium sp. nov. The type strain is CBA7301T (=KCCM 43355T=ATCC TSD-227T).

Safety assessment of white colony-forming yeasts in kimchi.

White colony-forming yeasts (WCFYs) have been reported to form a white colony on the surface of kimchi, resulting in the deterioration of kimchi sensory quality. However, toxicity of WCFY has rarely been studied. Thus, to evaluate the safety of WCFY (i.e., Kazachstania servazzii, Candia sake, and Pichia kudriavzevii), we conducted cell and animal experiments as well as genomic analysis. In vitro studies indicated that WCFY did not induce cytotoxic responses such as lactate dehydrogenase release, excessive oxidative stress, and mitochondrial damage at concentrations of up to 2.5 × 105 CFU/mL in human intestinal and liver cells. In animal studies using rats (single-dose and 14-day repeated-dose oral toxicity studies), WCFY did not induce death, clinical signs of toxicity, histological alterations of the liver, or increases in the expression of pro-inflammatory cytokines nor cytochrome P450-2E1 in liver tissue at concentrations of up to 5 × 108 CFU/head/day. Genomic analysis revealed that P. kudriavzevii did not harbor genes related to toxicity and antimicrobial resistance. Taken together, our data suggest that exposure to WCFY through kimchi intake did not induce toxic response in the Caco-2, HepG2, and Sprague-Dawley rats. The current work provides evidence for the safety of accidental major WCFY ingestion via kimchi.

Genomic analysis of facultatively oligotrophic haloarchaea of the genera Halarchaeum, Halorubrum, and Halolamina, isolated from solar salt.

Extremely halophilic archaea (haloarchaea) belonging to the phylum Euryarchaeota have been found in high-salinity environments. In this study, Halarchaeum sp. CBA1220, Halorubrum sp. CBA1229, and Halolamina sp. CBA1230, which are facultatively oligotrophic haloarchaea, were isolated from solar salt by culture under oligotrophic culture conditions. The complete genomes of strains CBA1220, CBA1229, and CBA1230 were sequenced and were found to contain 3,175,875, 3,582,278, and 3,465,332 bp, with a G + C content of 68.25, 67.66, and 66.75 mol %, respectively. In total, 60, 36, and 33 carbohydrate-active enzyme genes were determined in the respective strains. The strains harbored various genes encoding stress-tolerance proteins, including universal stress proteins, cold-shock proteins, and rubrerythrin and rubrerythrin-related proteins. The genome data produced in this study will facilitate further research to improve our understanding of other halophilic strains and promote their industrial application.

Aminipila terrae sp. nov., a strictly anaerobic bacterium isolated from river sediment.

In this study, aimed at investigating and characterizing river sediment bacteria, we isolated a Gram-stain-positive, rod-shaped, obligate anaerobic bacterium, strain CBA3637T, from the sediment of the Geum River. This strain grew at 10-40 °C (optimum, 30 °C), 0-1% NaCl (optimum, 0%), and pH 7-8 (optimum, pH 7). The 16S rRNA gene sequence comparison revealed Aminipila butyrica DSM 103574T to be the closest relative of strain CBA3637T (96.6-96.7% similarity); and both strains clustered together in phylogenetic analysis. The genome of strain CBA3637T was found to consist of a single chromosome (3.51 Mbp; 36.98% G + C content). Comparative genomic analysis of the strain CBA3637T with A. butyrica DSM 103574T revealed that strain CBA3637T possessed five unique pathways related to polyamine biosynthesis, lipopolysaccharide metabolism, pyrimidine metabolism, and cofactor and vitamin metabolism. Strain CBA3637T contained C14:0, C16:0, and C18:1 ω9c as the major fatty acids, and diphosphatidylglycerol as the major polar lipid. No respiratory quinone was observed. Biochemical, chemotaxonomic, and genotypic data revealed that the strain CBA3637T is a representative of a novel species within the genus Aminipila, for which the name Aminipila terrae is proposed. The type strain is CBA3637T (= KACC 21651T = DSM 110662T).

Anaerocolumna sedimenticola sp. nov., isolated from fresh water sediment.

Strain CBA3638T was isolated from the Geum River sediment, Republic of Korea. The cells of strain CBA3638T were Gram-stain-positive, strictly anaerobic, rod-shaped, and 0.5-1.0 µm wide, and 4.0-4.5 µm long. Optimal growth occurred at 37 °C, pH 7.0, and 1.0% (w/v) NaCl. Based on the 16S rRNA gene sequence, the phylogenetic analysis showed that strain CBA3638T belongs to the genus Anaerocolumna in the family Lachnospiraceae, and is most closely related to Anaerocolumna cellulosilytica (94.6-95.0%). The DDH value with A. cellulosilytica SN021T showed 15.0% relatedness. The genome of strain CBA3638T consisted of one circular chromosome that is 5,500,435 bp long with a 36.7 mol% G + C content. The genome contained seven 16S-5S-23S rRNA operons and one antibiotic resistance-related transporter gene (mefA). Quinones were not detected. The predominant cellular fatty acids were C16:0 and C14:0 and the polar lipids were diphosphatidylglycerol, phosphatidylcholine, and uncharacterised polar lipids. Based on the polyphasic taxonomic analysis, we propose strain CBA3638T as a novel species in the genus Anaerocolumna, with the name Anaerocolumna sedimenticola sp. nov. The type strain is CBA3638T (= KACC 21652T = DSM 110663T).

Water Nitrate Remote Monitoring System with Self-Diagnostic Function for Ion-Selective Electrodes.

The detection of nitrate pollutants is a widely used strategy for protecting water sources. Although ion-selective electrodes (ISEs) have been considered for the determination of ion concentrations in water, the accuracy of ISE technology decreases owing to the signal drift and decreasing sensitivity over time. The objectives of the present study were: (1) to develop an online water monitoring system mainly consisting of an Arduino board-based Internet-of-Things (IoT) device and nitrate ISEs; and (2) to propose a self-diagnostic function for monitoring and reporting the condition of the ISEs. The developed system communicates with the cloud server by using the message queuing telemetry transport (MQTT) protocol and provides monitoring information through the developed cloud-based webpage. In addition, the online monitoring system provides information on the electrode status, which is determined based on a self-diagnostic index (SDI, with a range of 0-100) of the electrode drift and sensitivity. The diagnostic method for monitoring and reporting the electrode status was validated in a one-month-long laboratory test followed by a field test in a stream near an agricultural facility. Moreover, a self-diagnostic index (SDI) was applied in the final field experiments with an accuracy of 0.77.

Raineyella fluvialis sp. nov., an actinobacterium isolated from freshwater sediment.

A novel, facultatively anaerobic actinobacterium, designated strain CBA3103T, was isolated from sediment of the Geum River in South Korea. Phylogenetic analysis indicated that strain CBA3103T is most closely related to Raineyella antarctica LZ-22T (98.47 % 16S rRNA gene sequence similarity). The genome of strain CBA3103T was 3 649 865 bp with a DNA G+C content of 69.6 mol%. The average nucleotide identity value between strain CBA3103T and R. antarctica LZ-22T was 79.22 %. Cells of strain CBA3103T were Gram-positive, rod-shaped, 0.6-0.9 µm wide and 1.4-2.4 µm long. Growth occurred at 15-40 °C (optimum, 35 °C), at pH 6.0-7.0 (optimum, pH 7.0) and with 0-2 % NaCl (w/v) (optimum, 0-1 %, w/v). The major cellular fatty acids in strain CBA3103T were anteiso-C15 : 0, anteiso-C15 : 1 A and iso-C14 : 0. The major respiratory quinone was menaquinone-9(H4). The polar lipids of strain CBA3103T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, five unidentified glycolipids and three unidentified phospholipids. Based on the genotypic, phenotypic and chemotaxonomic analyses, strain CBA3103T represents a novel species of the genus Raineyella, for which the name Raineyella fluvialis sp. nov. (type strain CBA3103T=KACC 21446T=DSM 110288T) is proposed.

Model Predictive Control via Output Feedback Neural Network for Improved Multi-Window Greenhouse Ventilation Control.

Maintaining environmental conditions for proper plant growth in greenhouses requires managing a variety of factors; ventilation is particularly important because inside temperatures can rise rapidly in warm climates. The structure of the window installed in a greenhouse is very diverse, and it is difficult to identify the characteristics that affect the temperature inside the greenhouse when multiple windows are driven, respectively. In this study, a new ventilation control logic using an output feedback neural-network (OFNN) prediction and optimization method was developed, and this approach was tested in multi-window greenhouses used for strawberry production. The developed prediction model used 15 inputs and achieved a highly accurate performance (R2 of 0.94). In addition, the method using an algorithm based on an OFNN was proposed for optimizing considered six window-opening behavior. Three case studies confirmed the optimization performance of OFNN in the nonlinear model and verified the performance through simulations. Finally, a control system based on this logic was used in a field experiment for six days by comparing two greenhouses driven by conventional control logic and the developed control logic; a comparison of the results showed RMSEs of 3.01 °C and 2.45 °C, respectively. It confirmed the improved control performance in comparison to a conventional ventilation control system.

Halorubrum aethiopicum sp. nov., an extremely halophilic archaeon isolated from commercial rock salt.

A novel extremely halophilic archaeon, designated SAH-A6T, was isolated from a sample of commercial rock salt in Ethiopia. Cells of SAH-A6T were aerobic and pleomorphic. The strain was able to grow at concentrations of 15-30 % (w/v) NaCl (optimum 20-25 % NaCl), at pH 6.0-9.0 (optimum pH 7.0) and in a temperature range of 30-55 °C (optimum 37-45 °C). Mg2+ was not required for growth of SAH-A6T cells. On the basis of 16S rRNA gene sequence analysis, strain SAH-A6T was closely related to Halorubrum halodurans Cb34T (99.1 %), Halorubrum rubrum YC87T (98.9 %), Halorubrum aquaticum EN-2T (98.7 %), Halorubrum cibi JCM 15757T (98.4 %), Halorubrum luteum CGSA15T (97.3 %), Halorubrum lipolyticum 9-3T (97.1 %), Halorubrum tibetense 8W8T (97.1 %), Halorubrum kocurii JCM 1478T (97.1 %), Halorubrum halophilum B8T (97.0 %) and Halorubrum persicum C49T (97.0 %). Phylogenetic analysis based on the rpoB' gene sequences showed that strain SAH-A6T was closely related to Hrr. halodurans Cb34T (99.7 %), Hrr. aquaticum JCM 14031T (99.3 %) and other members of the genus Halorubrum (<99.0 %). The DNA G+C content of the strain was 68.0 mol%. DNA-DNA hybridization between strain SAH-A6T and the most closely related members of the genus Halorubrum were below 55 %, suggesting that the new isolate constitutes a different genospecies. On the bases of chemotaxonomic, phenotypic and genotypic data, strain SAH-A6T (=KCCM 43215T=JCM 31519T) represents a novel species of the genus Halorubrum, for which the name Halorubrumaethiopicum sp. nov. is proposed.

Maribacter pelagius sp. nov., isolated from seawater.

A Gram-stain-negative, gliding, non-endospore-forming and slightly halophilic bacterial strain, CBA3204T, was isolated from seawater and characterized by polyphasic taxonomic analysis. Phylogenetic analysis based on 16S rRNA sequences revealed that strain CBA3204T formed a distinct lineage within the family Flavobacteriaceae. The 16S rRNA sequences of strain CBA3204T had a sequence similarity level of 96.96 % to Maribacter arcticus KOPRI 20941T as the nearest phylogenetic neighbour. The strain grew optimally at 25-30 °C and in the presence of 2-4 % (w/v) NaCl. The dominant menaquinone was MK-6 and the major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G. The DNA G+C content was 35.1 mol%. There were some differences in phenotypic properties among strain CBA3204T and other Maribacter species. On the basis of polyphasic analysis containing phenotypic, phylogenetic and chemotaxonomic data, strain CBA3204T (=KACC 17671T=JCM 19533T) is proposed as a novel species Maribacter pelagius sp. nov.

Aquimarina versatilis sp. nov., isolated from seashore sand, and emended description of the genus Aquimarina.

Strain CBA3207T, a novel Gram-stain-negative, aerobic and rod-shaped bacterium, was isolated from the seashore sand of Jeju island in South Korea. Strain CBA3207T grew optimally at 25-30 °C and pH 7.0-7.5 with 3.0-4.0 % (w/v) NaCl. It was catalase-positive, oxidase-negative, and hydrolysed starch, gelatin, and Tweens 20, 40 and 80. The 16S rRNA gene sequence of strain CBA3207T showed 96.0, 95.6, 95.6, 95.5 and 95.5 % similarity to that of Aquimarinamytili PSC33T, Aquimarinaagarivorans HQM9T, Aquimarinalatercula DSM 2041T, Aquimarinaintermedia KMM 6258T and Aquimarinaamphilecti 92VT, respectively. The major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 1 G and summed feature 9 (10-methyl C16 : 0 and/or iso-C17 : 1ω9c). The major respiratory quinone was menaquinone-6, and the major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and six unidentified lipids. The G+C content of the genomic DNA was 38.8 mol%. Based on phenotypic, genotypic and phylogenetic analyses, strain CBA3207T represents a novel species in the genus Aquimarina, for which the name Aquimarinaversatilissp. nov. is proposed. The type strain is CBA3207T (=KACC 17666T=JCM 19528T).

Aquimarina seongsanensis sp. nov., isolated from sea water.

An orange, rod-shaped, gliding bacterium, designated strain CBA3208T, was isolated from sea water of Jeju Island, Republic of Korea. Cells were observed to be Gram-stain negative, strictly aerobic, catalase positive and oxidase negative and to hydrolyse starch, gelatin, and Tweens 40 and 80. The major fatty acids were identified as iso-C15:0, iso-C17:0 3-OH, and iso-C15:1 G. The only isoprenoid quinone was found to be menaquinone-6 (MK-6) and the major polar lipids were identified as phosphatidylethanolamine, two aminolipids and four unidentified polar lipids. The DNA G+C content of strain CBA3208T was determined to be 34.9 mol%. Strain CBA3208T is considered to represent a novel species of the genus Aquimarina, for which the name Aquimarina seongsanensis sp. nov. is proposed based on this polyphasic taxonomic analysis. The type strain is CBA3208T (=KACC 17667T =JCM 19529T).

Actibacter haliotis sp. nov., isolated from the gut of an abalone, Haliotis discus hannai, and emended description of the genus Actibacter.

A novel strain, designated strain W113(T), was isolated from the gut of an abalone, Haliotis discus hannai, which was collected from the northern coast of Jeju in Korea. The isolate was a Gram-staining-negative, facultatively anaerobic, non-motile, rod-shaped bacterium producing yellow-to-orange carotenoid-type pigments. 16S rRNA gene sequence analysis showed that the isolate belonged to the genus Actibacter in the family Flavobacteriaceae and it shared the highest sequence similarity with the type strain of Actibacter sediminis (98.8 % similarity). Optimal growth occurred at 25 °C, at pH 7 and with 2 % (w/v) NaCl. The major cellular fatty acids were iso-C15:0, anteiso-C15:0 and iso-C15:1 G. Menaquinone-6 was the main respiratory quinone. The polar lipids of the isolate were phosphatidylethanolamine, three unidentified amino lipids, and three unidentified lipids. The genomic DNA G+C content was 42.6 mol% and DNA-DNA hybridization values indicated that the strain shared <18 % genomic relatedness with the most closely related species. The results of the phylogenetic, phenotypic and genotypic analyses indicated that strain W113(T) represents a novel species in the genus Actibacter, for which the name Actibacter haliotis sp. nov. is proposed. The type strain is W113(T) ( = KACC 17209(T) = JCM 18868(T)).

Corynebacterium atrinae sp. nov., isolated from the gastrointestinal tract of a pen shell, Atrina pectinata.

A novel Gram-stain-positive, non-motile, facultatively anaerobic and rod-shaped bacterium, strain PSPT56(T), was isolated from the gastrointestinal tract of a pen shell (Atrina pectinata). Optimal growth of strain PSPT56(T) was ascertained to occur at 30 °C, pH 8.0 and in the presence of 1-2 % (w/v) NaCl. The strain was catalase-positive and oxidase-negative. The major cellular fatty acids were C18 : 1ω9c, C16 : 0, C17 : 1ω8c and C17 : 0. Tuberculostearic acid was not present. The major cell-wall sugars were ribose, galactose, glucose and arabinose. Peptidoglycan amino acids were meso-diaminopimelic acid, alanine and glutamic acid. The predominant isoprenoid quinone was MK-8(H2). Strain PSPT56(T) contained phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid, two unidentified lipids and two unidentified amino-lipids. Mycolic acids were detected as constitutive components of the cell wall. A phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain PSPT56(T) was most closely related to Corynebacterium testudinoris M935/96/4(T) and Corynebacterium felinum M714/95/5(T) with 98.69 % and 97.01 % similarity, respectively. DNA-DNA hybridization experiments indicated less than 29.9 % relatedness to the phylogenetically closest species. The G+C content of genomic DNA was 67.6 mol%. The phenotypic, phylogenetic and genotypic analyses indicated that strain PSPT56(T) represents a novel species within the genus Corynebacterium, for which the name Corynebacterium atrinae is proposed. The type strain is PSPT56(T) ( = KACC 17525(T) = JCM 19266(T)).

Colorimetric Sensor Array for White Wine Tasting.

A colorimetric sensor array was developed to characterize and quantify the taste of white wines. A charge-coupled device (CCD) camera captured images of the sensor array from 23 different white wine samples, and the change in the R, G, B color components from the control were analyzed by principal component analysis. Additionally, high performance liquid chromatography (HPLC) was used to analyze the chemical components of each wine sample responsible for its taste. A two-dimensional score plot was created with 23 data points. It revealed clusters created from the same type of grape, and trends of sweetness, sourness, and astringency were mapped. An artificial neural network model was developed to predict the degree of sweetness, sourness, and astringency of the white wines. The coefficients of determination (R2) for the HPLC results and the sweetness, sourness, and astringency were 0.96, 0.95, and 0.83, respectively. This research could provide a simple and low-cost but sensitive taste prediction system, and, by helping consumer selection, will be able to have a positive effect on the wine industry.

Insect gut bacterial diversity determined by environmental habitat, diet, developmental stage, and phylogeny of host.

Insects are the most abundant animals on Earth, and the microbiota within their guts play important roles by engaging in beneficial and pathological interactions with these hosts. In this study, we comprehensively characterized insect-associated gut bacteria of 305 individuals belonging to 218 species in 21 taxonomic orders, using 454 pyrosequencing of 16S rRNA genes. In total, 174,374 sequence reads were obtained, identifying 9,301 bacterial operational taxonomic units (OTUs) at the 3% distance level from all samples, with an average of 84.3 (± 97.7) OTUs per sample. The insect gut microbiota were dominated by Proteobacteria (62.1% of the total reads, including 14.1% Wolbachia sequences) and Firmicutes (20.7%). Significant differences were found in the relative abundances of anaerobes in insects and were classified according to the criteria of host environmental habitat, diet, developmental stage, and phylogeny. Gut bacterial diversity was significantly higher in omnivorous insects than in stenophagous (carnivorous and herbivorous) insects. This insect-order-spanning investigation of the gut microbiota provides insights into the relationships between insects and their gut bacterial communities.

Actinomyces haliotis sp. nov., a bacterium isolated from the gut of an abalone, Haliotis discus hannai.

A novel, Gram-staining-positive, facultatively anaerobic, non-motile and coccus-shaped bacterium, strain WL80(T), was isolated from the gut of an abalone, Haliotis discus hannai, collected from the northern coast of Jeju in Korea. Optimal growth occurred at 30 °C, pH 7-8 and with 1% (w/v) NaCl. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that strain WL80(T) fell within the cluster of the genus Actinomyces, with highest sequence similarity to the type strains of Actinomyces radicidentis (98.8% similarity) and Actinomyces urogenitalis (97.0% similarity). The major cellular fatty acids were C18 : 1ω9c and C16 : 0. Menaquinone-10 (H4) was the major respiratory quinone. The genomic DNA G+C content of the isolate was 70.4 mol%. DNA-DNA hybridization values with closely related strains indicated less than 7.6% genomic relatedness. The results of physiological, biochemical, chemotaxonomic and genotypic analyses indicated that strain WL80(T) represents a novel species of the genus Actinomyces, for which the name Actinomyces haliotis sp. nov. is proposed. The type strain is WL80(T) ( = KACC 17211(T) = JCM 18848(T)).

Cloacibacterium haliotis sp. nov., isolated from the gut of an abalone, Haliotis discus hannai.

A novel Gram-stain-negative, aerobic, non-motile, yellow-pigmented and rod-shaped bacterium, designated strain WB5(T), was isolated from the intestinal tract of an abalone, Haliotis discus hannai, collected from the northern coast of Jeju in Korea. The isolate grew optimally at 30 °C, at pH 7 and in the presence of 0.5 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain WB5(T) was clustered in the genus Cloacibacterium and shared the highest sequence similarity with C. normanense (98.2 % similarity). The predominant fatty acids were iso-C15 : 0 and iso-C17 : 0 3-OH. Menaquinone-6 was the major respiratory quinone. The genomic DNA G+C content was 29.6 mol%. The DNA-DNA hybridization values indicated <22 % genomic relatedness with other members of the genus Cloacibacterium. The results of physiological, biochemical, chemotaxonomic and genotypic analyses showed that strain WB5(T) represents a novel species of the genus Cloacibacterium, for which the name Cloacibacterium haliotis sp. nov. is proposed. The type strain is WB5(T) ( = KACC 17210(T) = JCM 18869(T)).

Polaribacter atrinae sp. nov., isolated from the intestine of a comb pen shell, Atrina pectinata.

A novel Gram-staining-negative, aerobic, non-motile, yellow-to-orange carotenoid-type-pigmented and rod-shaped bacterium, designated strain WP25T, was isolated from the intestine of a comb pen shell, Atrina pectinata, which was collected from the South Sea near Yeosu in Korea. The isolate grew optimally at 20 °C, at pH 7 and with 2% (w/v) NaCl. 16S rRNA gene sequence analysis showed that strain WP25T belonged to the genus Polaribacter in the family Flavobacteriaceae and the highest sequence similarity was shared with the type strain of Polaribacter sejongensis (98.5%). The major cellular fatty acids were iso-C15:0, anteiso-C15:0, C15:1ω6c and iso-C15:0 3-OH. The main respiratory quinone was menaquinone MK-6. The polar lipids of strain WP25T were phosphatidylethanolamine, two unidentified aminolipids, an unidentified phospholipid and four unidentified lipids. The genomic DNA G+C content was 31.2 mol%. DNA-DNA hybridization experiments indicated <12.6% genomic relatedness with closely related strains. Based on phylogenetic, phenotypic and genotypic analyses, strain WP25T represents a novel species in the genus Polaribacter, for which the name Polaribacter atrinae sp. nov. is proposed, with the type strain WP25T (=KACC 17473T=JCM 19202T).

Advances in Culturomics Research on the Human Gut Microbiome: Optimizing Medium Composition and Culture Techniques for Enhanced Microbial Discovery.

Despite considerable advancements achieved using next-generation sequencing technologies in exploring microbial diversity, several species of the gut microbiome remain unknown. In this transformative era, culturomics has risen to prominence as a pivotal approach in unveiling realms of microbial diversity that were previously deemed inaccessible. Utilizing innovative strategies to optimize growth and culture medium composition, scientists have successfully cultured hard-to-cultivate microbes. This progress has fostered the discovery and understanding of elusive microbial entities, highlighting their essential role in human health and disease paradigms. In this review, we emphasize the importance of culturomics research on the gut microbiome and provide new theories and insights for expanding microbial diversity via the optimization of cultivation conditions.