Magnetite-driven Bio-Fenton degradation of chloroacetanilide herbicides by a newly isolated hydrogen peroxide producing bacterium Desemzia sp. strain C1.

The efficiency of the Fenton reaction is markedly contingent upon the operational pH related to iron solubility. Therefore, a heterogeneous Fenton reaction has been developed to function at neutral pH. In the present study, the Bio-Fenton reaction was carried out using magnetite (Fe(II)Fe(III)2O4) and H2O2 generated by a newly isolated H2O2-producing bacterium, Desemzia sp. strain C1 at pH 6.8 to degrade chloroacetanilide herbicides. The optimal conditions for an efficient Bio-Fenton reaction were 10 mM of lactate, 0.5% (w/v) of magnetite, and resting-cells (O.D.600 = 1) of strain C1. During the Bio-Fenton reaction, 1.8-2.0 mM of H2O2 was generated by strain C1 and promptly consumed by the Fenton reaction with magnetite, maintaining stable pH conditions. Approximately, 40-50% of the herbicides underwent oxidation through non-specific reactions of •OH, leading to dealkylation, dechlorination, and hydroxylation via hydrogen atom abstraction. These findings will contribute to advancing the Bio-Fenton system for non-specific oxidative degradation of diverse organic pollutants under in-situ environmental conditions with bacteria producing high amount of H2O2 and magnetite under a neutral pH condition.

Fungal biodegradation of poly(butylene adipate-co-terephthalate)-polylactic acid-thermoplastic starch based commercial bio-plastic film at ambient conditions.

Microbial biodegradation of commercially available poly(butylene adipate-co-terephthalate)-polylactic acid-thermoplastic starch based bio-plastic has been pursued at high temperatures exceeding 55 °C. Herein, we first reported three newly isolated fungal strains from farmland soil samples of Republic of Korea namely, Pyrenochaetopsis sp. strain K2, Staphylotrichum sp. S2-1, and Humicola sp. strain S2-3 were capable of degrading a commercial bio-plastic film with degradation rates of 9.5, 8.6, and 12.2%, respectively after 3 months incubation at ambient conditions. Scanning electron microscopy (SEM) analyses showed that bio-plastic film was extensively fragmented with severe cracking on the surface structure after incubation with isolated fungal strains. X-ray diffraction (XRD) analysis also revealed that high crystallinity of the commercial bio-plastic film was significantly decreased after degradation by fungal strains. Liquid chromatography-mass spectrometry (LC-MS) analyses of the fungal culture supernatants containing the bio-plastic film showed the peaks for adipic acid, terephthalic acid (TPA), and terephthalate-butylene (TB) as major metabolites, suggesting cleavage of ester bonds and accumulation of TPA. Furthermore, a consortium of fungal strain K2 with TPA degrading bacterium Pigmentiphaga sp. strain P3-2 isolated from the same sampling site exhibited faster degradation rate of the bio-plastic film within 1 month of incubation with achieving complete biodegradation of accumulated TPA. We assume that the extracellular lipase activity presented in the fungal cultures could hydrolyze the ester bonds of PBAT component of bio-plastic film. Taken together, the fungal and bacterial consortium investigated herein could be beneficial for efficient biodegradation of the commercial bio-plastic film at ambient conditions.

Highly effective biosorption capacity of Cladosporium sp. strain F1 to lead phosphate mineral and perovskite solar cell PbI2.

Fungus Cladosporium sp. strain F1 showed highly effective biosorption capacity to lead phosphate mineral and perovskite solar cells lead iodide compared to other fungi Aspergillus niger VKMF-1119 and Mucor ramannianus R-56. Scanning electron microscopy and transmission electron microscopy analyses shows that Cladosporium sp. strain F1, which previously showed high biosorption capacity to uranium phosphate nanorods and nanoplates, can accumulate lead phosphate mineral and lead iodide on the fungal hyphae surface in large amounts under a wide range of pH conditions, while A. niger VKMF-1119 and M. ramannianus R-56 adsorbed small amounts of minerals. After biosorption of lead iodide minerals on Cladosporium sp. strain F1, aqueous dimethyl sulfoxide (50%) at pH 2 (70 °C) released the mineral more than 99%. Based on the fungal surface analyses, hydrophobic properties on the surfaces of Cladosporium sp. strain F1 could affect the higher biosorption capacity of strain F1 to lead phosphate mineral and lead iodide as compared to other tested fungi. Cladosporium sp. strain F1 may be the novel biosorbents to remediate the phosphate rich environment and to recover lead from perovskite solar cells lead iodide.

In Vitro Comparison of Differences in Setting Time of Premixed Calcium Silicate-Based Mineral Trioxide Aggregate According to Moisture Content of Gypsum.

Recently, a paste-type premixed calcium silicate-based mineral trioxide aggregate (MTA) product that quickly solidifies through a pozzolanic reaction was introduced to replace existing MTA, which has the disadvantage of a long setting time. In this study, we evaluated the effect of moisture content in the root canal on the setting time of premixed calcium silicate-based MTA in a simulated root canal environment using Endoseal MTA and Well-Root ST, among commercially available products. The setting time was measured according to ISO 6876/2012. A mold made using grades 2, 3, and 4 dental gypsum according to the classification of ISO 6873/2013 was used to reproduce the difference in moisture environment. Differences in moisture content were measured using micro-computed X-ray tomography (micro-CT). The micro-CT results showed that the moisture content was the highest and lowest in the grade 2 and 4 gypsum molds, respectively. Moreover, the setting time indicated by the manufacturer was the shortest for the grade 2 gypsum mold. Hence, the differences in moisture content significantly affect the setting time of MTA. This result can help set future experimental conditions and develop premixed calcium silicate-based MTA products.

Draft Genome Sequence of Desemzia sp. Strain C1, Producing Hydrogen Peroxide, Isolated from Oil-Contaminated Soil.

Here, we report the draft genome sequence of Desemzia sp. strain C1, which was isolated from oil-contaminated soil in South Korea and produces hydrogen peroxide (H2O2). The genome of Desemzia sp. strain C1 contains genes encoding various oxidases involved in H2O2 production and resistance to oxidative stress.

Non-specific degradation of chloroacetanilide herbicides by glucose oxidase supported Bio-Fenton reaction.

Bio-Fenton reaction supported by glucose oxidase (GOx) for producing H2O2 was applied to degrade persistent chloroacetanilide herbicides in the presence of Fe (Ⅲ)-citrate at pH 5.5. There were pH decrease to 4.3, the production of 8 mM H2O2 and simultaneous consumption to produce •OH radicals which non-specifically degraded the herbicides. The degradation rates followed the order acetochlor ≈ alachlor ≈ metolachlor > propachlor ≈ butachlor with the degradation percent of 72.8%, 73.4%, 74.0%, 47.4%, and 43.8%, respectively. During the Bio-Fenton degradation, alachlor was dechlorinated and filtered into catechol via the production of intermediates formed through a series of hydrogen atom abstraction and hydrogen oxide radical addition reactions. The current Bio-Fenton reaction leading to the production of •OH radicals could be applied for non-specific oxidative degradation to various persistent organic pollutants under in-situ environmental conditions, considering diverse microbial metabolic systems able to continuously supply H2O2 with ubiquitous Fe(II) and Fe(III) and citrate.

Degradation of sulfonated polyethylene by a bio-photo-fenton approach using glucose oxidase immobilized on titanium dioxide.

Polyethylene (PE) plastics are highly recalcitrant and resistant to photo-oxidative degradation due to its chemically inert backbone structure. We applied two novel reactions such as, Bio-Fenton reaction using glucose oxidase (GOx) enzyme alone and Bio-Photo-Fenton reaction using GOx immobilized on TiO2 nanoparticles (TiO2-GOx) under UV radiation, for (bio)degradation of pre-activated PE with sulfonation (SPE). From both the reactions, GC-MS analyses identified small organic acids such as, acetic acid and butanoic acid as a major metabolites released from SPE. In the presence of UV radiation, 21 fold and 17 fold higher amounts of acetic acid (4.78 mM) and butanoic acid (0.17 mM) were released from SPE after 6 h of reaction using TiO2-GOx than free GOx, which released 0.22 mM and 0.01 mM of acetic acid and butanoic acid, respectively. Our results suggest that (bio)degradation and valorization of naturally weathered and oxidized PE using combined reactions of biochemistry, photochemistry and Fenton chemistry could be possible.

Paludirhabdus telluriireducens gen. nov., sp. nov. and Paludirhabdus pumila sp. nov., isolated from soil of a mountain wetland and emended description of Gorillibacterium massiliense.

Two strains of Gram-stain-positive, endospore-forming, motile by means of peritrichous flagella, aerobic or facultative anaerobic, and rod-shaped bacteria that were designated ON8T and ON6T were isolated from soil collected from a mountain wetland in Gwang-ju, Republic of Korea. The isolates were catalase-positive and oxidase-negative. Cells of ON8T and ON6T grew at 15-35 °C (optimal 30 °C) and 15-40 °C (optimal 30 °C), respectively. The major menaquinone was MK-7 and the major cellular fatty acids (>10 % of the total) were anteiso-C15 : 0, iso-C15 : 0, C14 : 0 and C16 : 0. The predominant polar lipids were diphosphatidylglycerol, aminophospholipid and phospholipid. Meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The DNA G+C contents of strains ON8T and ON6T were 50.6 and 53.5 mol%, respectively, and the 16S rRNA gene sequence analysis showed that the nearest phylogenetic neighbour of both strains was Gorillibacterium massiliense G5T (93.9 %), followed by the members of the genus Paenibacillus in the family Paenibacillaceae. The DNA-DNA hybridization relatedness value between ON8T and ON6T was 44.1 %, which indicated that they represented distinct species. Based on polyphasic characteristics, a novel genus is proposed with the name Paludirhabdus gen. nov., which consists of two species, Paludirhabdus telluriireducens sp. nov. (the type species; type strain ON8T=KACC 19267T=JCM 31958T) and Paludirhabdus pumila sp. nov. (type strain ON6T=KACC 19266T=JCM 31957T).

Ahniella affigens gen. nov., sp. nov., a gammaproteobacterium isolated from sandy soil near a stream.

A bacterial strain, designated D13T, was isolated from sandy soil near a stream in Sinan-gun, Republic of Korea. Cells were Gram-stain-negative, aerobic, non-motile and flexible rod-shaped. Growth occurred at 15-35 °C (optimum 30 °C) and pH 6.5-8.0 (pH 7.0). NaCl was not obligatory for growth but could be tolerated at up to 0.5 % (w/v) NaCl. The DNA G+C content of the genomic DNA of strain D13T was 57.7 mol% and a phylogenetic analysis of the 16S rRNA gene sequence revealed that strain D13T formed a distinct evolutionary lineage within the family Rhodanobacteraceae of the order Lysobacterales. Strain D13T showed highest 16S rRNA sequence similarity to Lysobacter hankyongensis KTCe-2T (92.7 %), followed by Luteimonas cucumeris Y4T (92.7 %), Dyella japonica XD53T (92.6 %) and Aquimonas voraii GPTSA 20T (92.5 %). The major cellular fatty acids (>10 % of the total) were iso-C16 : 0, iso-C15 : 0 and summed feature 9 (iso-C17 : 1ω9с and/or C16 : 0 10-methyl). The respiratory quinone was ubiquinone-8 and the major polar lipids of the isolate consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylmonomethylethanolamine. Based on polyphasic analysis, strain D13T could be differentiated from other genera in the family Rhodanobacteraceae, which suggests that strain D13T represents a novel species of a new genus in the family Rhodanobacteraceae, for which the name Ahniella affigens gen. nov., sp. nov. is proposed. The type strain is D13T (=KACC 19270T=JCM 31634T).

Roseomonas fluminis sp. nov. isolated from sediment of a shallow stream.

An aerobic, Gram-negative, motile by means of a single polar flagellum, and ovoid-shaped bacterium, designated D3T, was isolated from shallow stream sediments in Sinan-gun, South Korea. Growth occurred at 15-40 °C (optimum 35 °C), at pH 7.0-8.0 (optimum pH 7.0), and at an optimum NaCl concentration of 0.5 % (w/v). The major cellular fatty acids (>7 % of the total) were C16 : 0, C18 : 0 2-OH, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The predominant quinone was ubiquinone-10, and the G+C content of the genomic DNA of strain D3T was 73.1 mol%. The major polyamine was spermidine. The major polar lipids of the isolate were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain D3T clustered with Roseomonas aquatica TR53T within the genus Roseomonas. The 16S rRNA gene sequence of strain D3T showed the highest sequence similarity to R. aquatica TR53T (95.9 %), followed by Roseomonas rosea 173-96T (95.7 %) and Roseomonas aerilata 5420S-30T (95.0 %). Based on the phenotypic, phylogenetic and chemotaxonomic characterization, strain D3T represents a novel species of the genus Roseomonas, for which the name Roseomonas fluminis sp. nov. is proposed. The type strain is D3T (=KACC 19269T=JCM 31968T).

Sphingomonas silvisoli sp. nov., isolated from forest soil.

A novel Gram-stain-negative, aerobic, non-motile and short-rod-shaped bacterium, designated RP18T, was isolated from forest soil in Gwang-ju, Republic of Korea. Growth occurred at 15-30 °C (optimum 30 °C), pH 6.0-7.0 (optimum pH 7.0), and was inhibited in the presence of normal saline. According to the 16S rRNA gene sequence, strain RP18T showed the highest sequence similarity to Sphingomonas kyeonggiensis THG-DT81T (96.0 %), followed by Sphingomonas pituitosa EDIVT (95.4 %) and Sphingomonas dokdonensis DS-4T (95.2 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain RP18T was clustered with Sphingomonas gimensis 9PNM-6T and Sphingomonas jejuensis MS-31T under the genus Sphingomonas. The G+C content of the genomic DNA of strain RP18T was 61.5 mol%. The major cellular fatty acids (>6 % of the total) were C16 : 0, C14 : 0 2-OH, C17 : 1ω6с, summed feature 3 (C16 : 1ω7с and/or C16 : 1ω6с) and summed feature 8 (C18 : 1ω7с and/or C18 : 1ω6с). Ubiquinone-10 (Q-10) and sym-homospermidine were detected as the predominant respiratory quinone and major compound in the polyamine pattern, respectively. The major polar lipids of the isolate consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phospholipid and sphingoglycolipid. Based on phylogenetic analysis and physiological and biochemical characterization, strain RP18T represents a novel species of the genus Sphingomonas, for which the name Sphingomonas silvisoli sp. nov. is proposed. The type strain is RP18T (=KACC 18914T=JCM 31801T).