Kinetic, genomic, and physiological analysis reveals diversity in the ecological adaptation and metabolic potential of Brachybacterium equifaecis sp. nov. isolated from horse feces.

Brachybacterium species have been identified in various ecological niches and belong to the family Dermabacteriaceae within the phylum Actinobacteria. In this study, we isolated a novel Brachybacterium equifaecis JHP9 strain from horse feces and compared its kinetic, biochemical, and genomic features with those of other Brachybacterium strains. Moreover, comparative genomic analysis using publicly available Brachybacterium genomes was performed to determine the properties involved in their ecological adaptation and metabolic potential. Novel species delineation was determined phylogenetically through 16S rRNA gene similarity (up to 97.9%), average nucleotide identity (79.5-82.5%), average amino acid identity (66.7-75.8%), and in silico DNA-DNA hybridization (23.7-27.9) using closely related strains. This study also presents the first report of the kinetic properties of Brachybacterium species. Most of the Brachybacterium strains displayed high oxygen (K m(app) =1.6-24.2 µM) and glucose (K m(app) =0.73-1.22 µM) affinities, which may manifest niche adaptations. Various carbohydrate metabolisms under aerobic and anaerobic conditions, antibiotic resistance, mobile genetic elements, carbohydrate-active enzymes, lactic acid production, and the clustered regularly interspaced short palindromic repeats-Cas and bacteriophage exclusion systems were observed in the genotypic and/or phenotypic properties of Brachybacterium species, suggesting their genome flexibility, defense mechanisms, and adaptability. Our study contributes to the knowledge of the kinetic, physiological, and genomic properties of Brachybacterium species, including the novel JHP9 strain, which advocates for their tolerant and thriving nature in various environments, leading to their ecological adaptation. IMPORTANCE Basic physiological and genomic properties of most of the Brachybacterium isolates have been studied; however, the ability of this bacterium to adapt to diverse environments, which may demonstrate its role in niche differentiation, is to be identified yet. Therefore, here, we explored cellular kinetics, metabolic diversity, and ecological adaptation/defensive properties of the novel Brachybacterium strain through physiological and comparative genomic analysis. In addition, we presented the first report examining Brachybacterium kinetics, indicating that all strains of Brachybacterium, including the novel one, have high oxygen and glucose affinity. Furthermore, the comparative genomic analysis also revealed that the novel bacterium contains versatile genomic properties, which provide the novel bacterium with significant competitive advantages. Thus, in-depth genotypic and phenotypic analysis with kinetic properties at the species level of this genus is beneficial in clarifying its differential characteristics, conferring the ability to inhabit diverse ecological niches.

Microbial mediated reaction of dimethylarsinic acid in wetland water and sediments.

The biogeochemical reactions of dimethylarsinic acid (DMAs(V)) were investigated using simulated wetland systems in a laboratory. DMAs(V) was injected into the wetland water, and the As concentrations in the water, plants, and sediments were monitored. Aqueous and solid-phase As speciation was evaluated, and the results revealed that the DMAs(V) was completely transported to the sediments and plants. X-ray absorption spectroscopic measurement of the As in the sediment revealed that approximately 85-95% of As existed as inorganic As species, demonstrating the important role of microorganisms in the biogeochemical reaction of DMAs(V). The influences of microbes were further investigated in smaller batches under aerobic and anaerobic conditions. The microbial batch results showed that DMAs(V) demethylation reduced the total aqueous As concentration, demonstrating that As(V) has higher affinity to wetland sediment than DMAs(V). The redox conditions were also revealed as an important controlling factor of the As reaction and, under anaerobic conditions, we observed the presence of the most toxic form of inorganic As(III) in the aqueous phase. Although this study reports one example from a specific wetland, the important roles of the redox conditions and microbial influences were identified from the comprehensive analysis of As speciation and mass balance.

Undibacter mobilis gen. nov., sp. nov. isolated from an artificial wetland in Okcheon, Korea.

Strain GY_HT was isolated from an artificial wetland in Okcheon, Chungcheongbuk-do Province, Republic of Korea. Strain GY_HT was closely related to Pseudolabrys taiwanensis CC-BB4T based on 16S rRNA gene sequences (94.7 % similarity) and clustered within the family Nitrobacteraceae. Cells of the isolate were Gram-stain-negative, catalase-negative and oxidase-positive, and colonies were white or pale transparent. A flagellum was observed, and the isolate could respire both aerobically and anaerobically. Growth of GY_ HT was observed in the following conditions: 10-45 °C, pH 5-11 and 0-4 % NaCl. The optimal conditions for growth were 25 °C, pH 6.5-7.5 and 0.5-1.5 % NaCl. The major fatty acids were C19 : 0 cyclo ω8c (35.8 %) and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c; 27.4 %). The major quinone was found to be ubiquinone-10. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine were the major polar lipids. The G+C content of the genome of GY_HT was 63.3 mol%. Based on its phylogenomic, physiological and biochemical attributes, strain GY_HT represents a novel species of a novel genus of the family Nitrobacteraceae. We propose the name as Undibacter mobilis gen. nov., sp. nov. The type strain is GY_HT (=KCTC 62792T=JCM 32856T).

Genomic and Physiological Properties of a Facultative Methane-Oxidizing Bacterial Strain of Methylocystis sp. from a Wetland.

Methane-oxidizing bacteria are crucial players in controlling methane emissions. This study aimed to isolate and characterize a novel wetland methanotroph to reveal its role in the wetland environment based on genomic information. Based on phylogenomic analysis, the isolated strain, designated as B8, is a novel species in the genus Methylocystis. Strain B8 grew in a temperature range of 15 °C to 37 °C (optimum 30-35 °C) and a pH range of 6.5 to 10 (optimum 8.5-9). Methane, methanol, and acetate were used as carbon sources. Hydrogen was produced under oxygen-limited conditions. The assembled genome comprised of 3.39 Mbp and 59.9 mol% G + C content. The genome contained two types of particulate methane monooxygenases (pMMO) for low-affinity methane oxidation (pMMO1) and high-affinity methane oxidation (pMMO2). It was revealed that strain B8 might survive atmospheric methane concentration. Furthermore, the genome had various genes for hydrogenase, nitrogen fixation, polyhydroxybutyrate synthesis, and heavy metal resistance. This metabolic versatility of strain B8 might enable its survival in wetland environments.

Ferrovibrio terrae sp. nov., isolated from soil.

Designated strain K5T was isolated from soil on Jeju Island. The bacterium was aerobic, Gram-stain-negative, oxidase-positive, catalase-low activity, motile, short-rod shaped, opaque and formed white colonies that were circular, raised and had entire margins. Strain K5T was able to grow at 15-40 °C, pH 4-9 and at 0-2 % (w/v) NaCl concentration. Phylogenetic analysis based on its 16S rRNA gene sequences indicated that strain K5T is closely related to Ferrovibrio soli A15T (98.9 % sequence similarity), Ferrovibrio denitrificans Sp-1T (98.7 %) and Ferrovibrio xuzhouensis LM-6T (97.4 %). The sole respiratory quinone was determined to be ubiquinone-10. The dominant fatty acids of strain K5T were summed feature 8 (C18 : 1 ω7c / C18 : 1ω6c, 29.8 %), C19 : 0 cyclo ω8c (20.2 %) and C16 : 0 (24.4 %). DNA G+C content was 63.6 % and DNA-DNA relatedness between strain K5T and other three members of the genus Ferrovibrio ranged from 24 to 28 %. The major polar lipids were identified as phosphatidylglycerol, phosphatidylethanolamine and aminolipids. Moreover, polyphasic characterization revealed that strain K5T represents a novel species in the genus Ferrovibrio, for which the name Ferrovibrio terrae sp. nov. is proposed. The type strain is K5T (=KCCM 43295T=LMG 30611T).

Sphingorhabdus pulchriflava sp. nov., isolated from a river.

A facultatively anaerobic and Gram-stain-negative bacterium, strain GY_GT, was isolated from a river (Daedeock-cheon) in Daejeon, Republic of Korea. The isolate was catalase-positive, oxidase-positive and formed yellow colonies. Strain GY_GT was phylogenetically classified as belonging in the genus Sphingorhabdus. Its closely related strains were Sphingorhabdus wooponensis 03SU3-PT (97.1 % similarity), Sphingorhabdus buctiana T5T (96.9 %), Sphingorhabdus contaminans JC216T (96.5 %), Sphingorhabdus rigui 01SU5-PT (96.5 %) and Sphingorhabdus planktonica G1A_585T (96.3 %) based on 16S rRNA gene sequences. The growth conditions for GY_GT were at 10-45 °C (optimum, 25 °C), pH 6-10 (pH 7) and 0-4% NaCl (0.5-1.5 %). Strain GY_GT could utilize turanose, d-fructose-6-phosphate, glucuronamide, α-keto-glutaric acid and acetoacetic acid. The major fatty acids of strain GY_GT were summed features 8 (C18 : 1 ω7c/C18 : 1 ω6c; 40.6 %) and 3 (C16 : 1 ω6c/C16 : 1 ω7c; 24.7 %). The major quinone required for respiration was Q-10. The polar lipids of strain GY_GT were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and sphingolipid. The G+C content of the genome was 57.7 mol%. The average nucleotide identity and average amino acid identity values between strains GY_GT and S. wooponensis were 71.0 and 72.7 %, respectively. Based on phylogenetic and phenotypic attributes, we suggest that strain GY_GT is a novel species in the genus Sphingorhabdus and propose the name Sphingorhabdus pulchriflava. The type strain is GY_GT (=KCTC 62791T=JCM 32855T).

Surface calcification of hydrophilic acrylic intraocular lens related to inflammatory membrane formation after combined vitrectomy and cataract surgery.

UNLABELLED: Two patients complained of blurred vision approximately 6 months after having combined vitrectomy and phacoemulsification with implantation of a C-flex 570C hydrophilic acrylic intraocular lens (IOL). Multiple granules were noted on the anterior surface of the IOLs in both patients. Intraocular lens exchange was performed in both eyes, and the explanted IOLs were sent for histopathological analysis. Scanning electron microscopy confirmed the presence of cracks and granules on the IOL surfaces and energy-dispersive x-ray spectroscopy demonstrated calcium deposition. Based on the calcification pattern on the anterior surface of the IOLs, 2 additional cases of opacification were identified under slitlamp examination. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Long-term stability and visual outcomes of a single-piece, foldable, acrylic intraocular lens for scleral fixation.

PURPOSE: To report long-term visual outcomes and complications of a new foldable, one-piece, acrylic posterior chamber intraocular lens with closed-loop haptics (C-flex, Rayner, UK) for scleral fixation. STUDY DESIGN: Retrospective interventional case series of 29 eyes of 29 patients who underwent scleral fixation with the C-flex intraocular lens in the absence of capsular support. METHODS: Review of 29 consecutive cases from January 2001 to December 2005 in which scleral fixation was performed with the C-flex intraocular lens. All cases were performed by a single surgeon (S.J.L.) and with an ab externo two-point scleral fixation technique. Preoperative status, intraoperative complications, and postoperative outcomes were analyzed. RESULTS: Mean best corrected visual acuity improved from 20/150 to 20/40 (P < 0.001) at 1 month and to 20/50 (P < 0.001) at mean follow-up of 41 months. Complications included clinically insignificant decentration [1 (3%)], mild intraoperative vitreous hemorrhage [1 (3%)], postoperative hyphema [2 (7%)], and transient elevated intraocular pressure [2 (7%)]. All complications were mild and resolved without the need for reoperation. CONCLUSION: Scleral fixation of the closed-loop, foldable, acrylic C-flex intraocular lens appeared to reduce operative time, was associated with minimal postoperative complications, and resulted in long-term visual improvement.