Nitrogen fertilization modulates beneficial rhizosphere interactions through signaling effect of nitric oxide.

Chemical nitrogen (N) fertilization is customary for increasing N inputs in agroecosystems. The nutritional effects of N fertilization on plants and soil microbes have been well studied. However, the signaling effects of N fertilization on rhizosphere plant-microbe interactions and the following feedback to plant performance remain unknown. Here, we investigated the effect of different N fertilizations on the behavior of the plant growth-promoting rhizobacteria (PGPR) Bacillus velezensis SQR9 in the cucumber (Cucumis sativus L.) rhizosphere. Moderate N fertilization promoted higher rhizosphere colonization of strain SQR9 than insufficient or excessive N input. Nitric oxide (NO) produced through the denitrification process under N fertilization was identified as the signaling molecule that dominates the root colonization of PGPR, and this effect could be neutralized by the NO-specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxy-3-oxide. Gene expression analysis demonstrated that NO regulated the biofilm formation of strain SQR9 by affecting the synthesis of extracellular matrix γ-polyglutamic acid, consequently impacting its root colonization. Finally, we demonstrated that moderate N fertilization-modulated enhanced PGPR root colonization can significantly promote plant growth and nitrogen use efficiency. This study provides insights into our understanding of the beneficial rhizosphere plant-microbe interactions under N fertilization and suggests that rational fertilization is critical to promote beneficial rhizosphere interactions for sustainable agricultural production.

Genomics assisted characterization of plant growth-promoting and metabolite producing psychrotolerant Himalayan Chryseobacterium cucumeris PCH239.

Here, we report the first complete genome of a psychrotolerant and yellow-pigmented rhizobacteria Chryseobacterium cucumeris PCH239. It was obtained from the rhizospheric soil of the Himalayan plant Bergenia ciliata. The genome consists of a single contig (5.098 Mb), 36.3% G + C content, and 4899 genes. The cold adaptation, stress response, and DNA repair genes promote survivability in a high-altitude environment. PCH239 grows in temperature (10-37 °C), pH (6.0-8.0), and NaCl (2.0%). The genome derived plant growth-promoting activities of siderophore production (siderophore units 53 ± 0.6), phosphate metabolism (PSI 5.0 ± 0.8), protease, indole acetic acid production (17.3 ± 0.5 µg/ml), and ammonia (2.89 ± 0.4 µmoles) were experimentally validated. Interestingly, PCH239 treatment of Arabidopsis seeds significantly enhances germination, primary, and hairy root growth. In contrast, Vigna radiata and Cicer arietinum seeds had healthy radicle and plumule elongation, suggesting varied plant growth-promotion effects. Our findings suggested the potential of PCH239 as a bio-fertilizer and biocontrol agent in the challenging conditions of cold and hilly regions.

Enhanced protein glutaminase production from Chryseobacterium proteolyticum combining physico-chemical mutagenesis and resistance screening and its application to soybean protein isolates.

BACKGROUND: Protein glutaminase (PG) is a novel protein modification biotechnology that is increasingly being used in the food industry. However, the current level of fermentation of PG-producing strains still does not meet the requirements of industrial production. To obtain the mutant strains with high PG production, the atmospheric and room temperature plasma (ARTP) combined with LiCl chemical mutagen were used in mutagenesis of a PG producing Chryseobacterium proteolyticum 1003. RESULTS: A mutant strain (WG15) was successfully obtained based on malonic acid resistance screening after compound mutagenesis of the starting strain C. proteolyticum 1003 using ARTP with LiCl, and it was confirmed to be genetically stable in PG synthesis after 15 generations. The protein glutaminase production of WG15 was 2.91 U mL-1 after optimization of fermentation conditions, which is 48.69% higher than the original strain C. proteolyticum 1003. The PG obtained from fermentation showed good activities in deamidation of soy protein isolate. The solubility and foaming properties of the PG-treated soy protein isolate were significantly increased by 36.50% and 10.03%, respectively, when PG was added at the amount of 100 U mL-1 . In addition, the emulsifying activity and emulsion stability of the treated soy protein isolate were improved by 12.44% and 10.34%, respectively, on the addition of 10 U mL-1 PG. The secondary structure of the soy protein isolate changed after PG treatment, with an increased proportion of glutamate. CONCLUSION: The results of the present study indicate that the PG produced by this mutant strain could improve the functional properties of soybean protein isolate and the C. proteolyticum mutant WG15 has great potential in food industry. © 2023 Society of Chemical Industry.

Microbial bioconversion of feathers into antioxidant peptides and pigments and their liposome encapsulation.

OBJECTIVES: The co-encapsulation of bioactive peptides obtained from degradation of chicken feathers and flexirubin-type pigment produced by Chryseobacterium sp. kr6 into phosphatidylcholine liposomes was investigated. RESULTS: Control empty liposomes showed mean diameter of 168.5 nm, varying to 185.4, 102.0 and 98.5 nm after the encapsulation of peptides, pigment and their co-encapsulation, respectively. Control liposomes presented zeta potential of - 20.9 mV, while the formulations containing the bioactive compounds showed values of - 30 mV or higher in magnitude. Infrared analysis revealed typical spectra for phosphatidylcholine, suggesting that no new chemical bonds were formed after encapsulation. ABTS radical scavenging assay showed that the antioxidant activity of the compounds was maintained after encapsulation. CONCLUSIONS: Feather waste can be a valuable substrate for simultaneous production of antioxidant peptides and pigment by Chryseobacterium sp. kr6, and their encapsulation into liposomes may be a suitable alternative for delivery of these natural antioxidants.

Genomic and functional insights into the adaptation and survival of Chryseobacterium sp. strain PMSZPI in uranium enriched environment.

Metal enriched areas represent important and dynamic microbiological ecosystems. In this study, the draft genome of a uranium (U) tolerant bacterium, Chryseobacterium sp. strain PMSZPI, isolated from the subsurface soil of Domiasiat uranium ore deposit in Northeast India, was analyzed. The strain revealed a genome size of 3.8 Mb comprising of 3346 predicted protein-coding genes. The analysis indicated high abundance of genes associated with metal resistance and efflux, transporters, phosphatases, antibiotic resistance, polysaccharide synthesis, motility, protein secretion systems, oxidoreductases and DNA repair. Comparative genomics with other closely related Chryseobacterium strains led to the identification of unique inventory of genes which were of adaptive significance in PMSZPI. Consistent with the genome analysis, PMSZPI showed superior tolerance to uranium and other heavy metals. The metal exposed cells exhibited transcriptional induction of metal translocating PIB ATPases suggestive of their involvement in metal resistance. Efficient U binding (~90% of 100 µM U) and U bioprecipitation (~93-94% of 1 mM U at pH 5, 7 and 9) could be attributed as uranium tolerance strategies in PMSZPI. The strain demonstrated resistance to a large number of antibiotics which was in agreement with in silico prediction. Reduced gliding motility in the presence of cadmium and uranium, enhanced biofilm formation on uranium exposure and tolerance to 1.5 kGy of 60Co gamma radiation were perceived as adaptive responses in PMSZPI. Overall, the positive correlation observed between uranium/metal tolerance abilities predicted using genome analysis and the functional characterization reinforced the multifaceted adaptation strategies employed by PMSZPI for its survival in the soil of uranium ore deposit comprising of high concentrations of uranium and other heavy metals.

Chryseobacterium chungangensis sp. nov., a bacterium isolated from soil of sweet gourd garden.

A novel bacterial strain, named MAH-7T, was isolated from a soil sample of a Korean sweet gourd garden and was characterized using a polyphasic approach. Cells were Gram-staining negative, orange colored, non-motile and rod shaped. The strain was aerobic and catalase, oxidase positive, optimum growth temperature and pH were 28-30 °C and 7.0, respectively. On the basis of 16S rRNA gene sequence analysis, strain MAH-7T belongs to the genus Chryseobacterium and is most closely related to Chryseobacterium formosense CC-H3-2T (97.96%) and Chryseobacterium zeae JM-1085T (97.19%). In DNA-DNA hybridization tests, the DNA relatedness between strain MAH-7T and its closest phylogenetic neighbors were below 45.0%. The DNA G+C content was 37.6 mol% and the predominant respiratory quinone was menaquinone-6 (MK-6). Flexirubin-type pigments were found to be present. The major cellular fatty acids were C15:0 iso, C17:0 iso 3OH, C17:1 isoω9c and summed feature 3 (C16:1ω7c and/or C16:1ω6c). The DNA-DNA hybridization results and results of the genotypic analysis in combination with chemotaxonomic and physiological data demonstrated that strain MAH-7T represented a novel species within the genus Chryseobacterium, for which the name Chryseobacterium chungangensis is proposed. The type strain is MAH-7T (= KACC 19293T = CGMCC 1.16232T). The NCBI GenBank accession number for the 16S rRNA gene sequence of strain MAH-7T is KY964274.

Single mutations of ketoreductase ChKRED20 enhance the bioreductive production of (1S)-2-chloro-1-(3, 4-difluorophenyl) ethanol.

(1S)-2-chloro-1-(3, 4-difluorophenyl) ethanol ((S)-CFPL) is an intermediate for the drug ticagrelor, and is manufactured via chemical approaches. To develop a biocatalytic solution to (S)-CFPL, an inventory of ketoreductases from Chryseobacterium sp. CA49 were rescreened, and ChKRED20 was found to catalyze the reduction of the ketone precursor with excellent stereoselectivity (>99 % ee). After screening an error-prone PCR library of the wild-type ChKRED20, two mutants, each bearing a single amino acid substitution of H145L or L205M, were identified with significantly increased activity. Then, the two critical positions were each randomized by constructing saturation mutagenesis libraries, which delivered several mutants with further enhanced activity. Among them, the mutant L205A was the best performer with a specific activity of 178 µmol/min/mg, ten times of that of the wild-type. Its k cat/K m increased by 15 times and half-life at 50 °C increased by 70 %. The mutant catalyzed the complete conversion of 150 and 200 g/l substrate within 6 and 20 h, respectively, to yield enantiopure (S)-CFPL with an isolated yield of 95 %.

Comparing PTR-MS profile of milk inoculated with pure or mixed cultures of spoilage bacteria.

The volatile organic compounds (VOCs) associated with UHT milk (n=8) inoculated with either pure inoculums of Pseudomonas fluorescens (two strains tested) or Chryseobacterium sp., or with mixed cultures of 2 or all 3 of the bacterial strains, and held at 4.5 °C for up to 26 days was measured using proton transfer reaction - mass spectrometry (PTR-MS). The VOCs evolved included a range of carbonyl compounds, alcohols, esters, and acids and had significant qualitative and quantitative differences between the inoculums. Milks inoculated with paired (mixed) bacterial cultures attained patterns similar to the VOC composition of one of the pure inoculums, which could be attributed to the domination of these bacteria within the mixed inoculum. This study will help to characterize the spoilage of milk and provide important insights into understanding the factors that limit the shelf life of milk.

Characterization of a novel oxyfluorfen-degrading bacterial strain Chryseobacterium aquifrigidense and its biochemical degradation pathway.

Persistent use of the diphenyl ether herbicides oxyfluorfen may seriously increase the health risks and ecological safety problems. A newly bacterium R-21 isolated from active soil was able to degrade and utilize oxyfluorfen as the sole carbon source. R-21 was identified as Chryseobacterium aquifrigidense by morphology, physiobiochemical characteristics, and genetic analysis. Under the optimum cultural conditions (pH 6.9, temperature 33.4 °C, and inoculum size 0.2 g L(-1)), R-21 could degrade 92.1 % of oxyfluorfen at 50 mg L(-1) within 5 days. During oxyfluorfen degradation, six metabolites were detected and identified by atmospheric pressure gas chromatography coupled to quadrupole-time of flight mass spectrometry and ultra-performance liquid chromatography coupled to quadrupole-time of flight mass spectrometry, and a plausible degradation pathway was deduced. Strain R-21 is a promising potential in bioremediation of oxyfluorfen-contaminated environments.

Chryseobacterium panacis sp. nov., isolated from ginseng soil.

A novel strain, DCY107(T), was isolated from soil collected from a ginseng field in Gochang, Republic of Korea. Strain DCY107(T) is Gram-negative, yellow pigmented, non-motile, non-flagellate, rod-shaped and aerobic. The strain was found to grow optimally at 25-30 °C and pH 6.5-7. Phylogenetically, strain DCY107(T) is closely related to Chryseobacterium polytrichastri DSM 26899(T) (98.49 % 16S rRNA gene sequence similarity), Chryseobacterium yeoncheonense JCM 18516(T) (97.78 %), Chryseobacterium aahli LMG 27338(T) (97.74 %), Chryseobacterium limigenitum LMG28734(T) (97.74 %), Chryseobacterium ginsenosidimutans JCM 16719(T) (97.47 %) and Chryseobacterium gregarium LMG 24052(T) (97.31 %). The DNA-DNA relatedness values between strain DCY107(T) and reference strains were found to be clearly below 70 %. The DNA G+C content of strain DCY107(T) was determined to be 34.2 mol%. The predominant quinone was identified menaquinone 6 (MK-6). The major polar lipids were identified as phosphatidylethanolamine and unidentified lipids: aminolipids AL1, AL2 and lipid L2. C16:00, iso-C15:00, iso-C15:02OH, iso-C17:03OH and summed feature 9 (iso-C17:1 ω9c and/or C16:0 10-methyl) were identified as the major fatty acids present in strain DCY107(T). The results of physiological and biochemical tests allowed strain DCY107(T) to be differentiated phenotypically from other recognised species belonging to the genus Chryseobacterium. Therefore, it is suggested that the newly isolated organism represents a novel species, for which the name Chryseobacterium panacis sp. nov. is proposed, with the type strain designated as DCY107(T) (=CCTCC AB 2015195(T) = KCTC 42750(T)).

Biochemical Characterization of CPS-1, a Subclass B3 Metallo-ß-Lactamase from a Chryseobacterium piscium Soil Isolate.

CPS-1 is a subclass B3 metallo-ß-lactamase from a Chryseobacterium piscium isolate collected from soil, showing 68% amino acid identity to the GOB-1 enzyme. CPS-1 was overproduced in Escherichia coli Rosetta (DE3), purified by chromatography, and biochemically characterized. This enzyme exhibits a broad-spectrum substrate profile, including penicillins, cephalosporins, and carbapenems, which overall resembles those of L1, GOB-1, and acquired subclass B3 enzymes AIM-1 and SMB-1.

Comparison of the growth kinetics and proteolytic activities of Chryseobacterium species and Pseudomonas fluorescens.

The effect of temperature on the growth kinetics and proteolytic activity of Chryseobacterium joostei and Chryseobacterium bovis was determined during this study. The results were compared with the activities of Pseudomonas fluorescens, which is regarded to be a major food spoilage psychrotolerant microorganism. For the growth studies, cultures were incubated in nutrient broth in a temperature gradient incubator (from 9 to 50 °C) and separately at 4 °C, and the optical density was measured at different time intervals. Growth temperature profiles for each organism were constructed. For determination of proteolytic activity, the cultures were incubated in fat-free ultra-high temperature processed milk in the temperature gradient incubator for 72 h (temperature range as above). Cell-free extracts were used to determine the proteolytic activity using the azocasein method. Results of the growth studies showed that C. joostei had the ability to grow over a wider temperature range than C. bovis and P. fluorescens without being affected by changes in the temperature. For the proteolytic activity, C. joostei had significantly (p < 0.001) higher activity per milligram of protein at 15.5 °C, followed by C. bovis and P. fluorescens. The results showed that C. joostei potentially has an even greater spoilage capacity in milk on the basis of growth rate and proteolytic activity than did P. fluorescens.

Novel Chryseobacterium sp. PYR2 degrades various organochlorine pesticides (OCPs) and achieves enhancing removal and complete degradation of DDT in highly contaminated soil.

Long term residues of organochlorine pesticides (OCPs) in soils are of great concerning because they seriously threaten food security and human health. This article focuses on isolation of OCP-degrading strains and their performance in bioremediation of contaminated soil under ex situ conditions. A bacterium, Chryseobacterium sp. PYR2, capable of degrading various OCPs and utilizing them as a sole carbon and energy source for growth, was isolated from OCP-contaminated soil. In culture experiments, PYR2 degraded 80-98% of hexachlorocyclohexane (HCH) or 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) isomers (50 mg L(-1)) in 30 days. A pilot-scale ex situ bioremediation study of highly OCP-contaminated soil augmented with PYR2 was performed. During the 45-day experimental period, DDT concentration was reduced by 80.3% in PYR2-augmented soils (35.37 mg kg(-1) to 6.97 mg kg(-1)) but by only 57.6% in control soils. Seven DDT degradation intermediates (metabolites) were detected and identified in PYR2-augmented soils: five by GC/MS: 1,1-dichloro-2,2-bis (4-chlorophenyl) ethane (DDD), 1,1-dichloro-2,2-bis (4-chlorophenyl) ethylene (DDE), 1-chloro-2,2-bis (4-chlorophenyl) ethylene (DDMU), 1-chloro-2,2-bis (4-chlorophenyl) ethane (DDMS), and dichlorobenzophenone (DBP); and two by LC/MS: 4-chlorobenzoic acid (PCBA) and 4-chlorophenylacetic acid (PCPA). Levels of metabolites were fairly stable in control soils but varied greatly with time in PYR2-augmented soils. Levels of DDD, DDMU, and DDE in PYR2-augmented soils increased from day 0 to day 30 and then decreased by day 45. A DDT biodegradation pathway is proposed based on our identification of DDT metabolites in PYR2-augmented systems. PYR2 will be useful in future studies of OCP biodegradation and in bioremediation of OCP-contaminated soils.

Chryseobacterium zeae sp. nov., Chryseobacterium arachidis sp. nov., and Chryseobacterium geocarposphaerae sp. nov. isolated from the rhizosphere environment.

Four yellow pigmented strains (91A-561(T), 91A-576, 91A-593(T), and JM-1085(T)) isolated from plant materials, showed 97.2-98.7 % 16S rRNA gene sequence similarities among each other and were studied in a polyphasic approach for their taxonomic allocation. Cells of all four isolates were rod-shaped and stained Gram-negative. Comparative 16S rRNA gene sequence analysis showed that the four bacteria had highest sequence similarities to Chryseobacterium formosense (97.2-98.7 %), Chryseobacterium gwangjuense (97.1-97.8 %), and Chryseobacterium defluvii (94.6-98.0 %). Sequence similarities to all other Chryseobacterium species were below 97.5 %. Fatty acid analysis of the four strains showed Chryseobacterium typical profiles consisting of major fatty acids C15:0 iso, C15:0 iso 2-OH/C16:1 ω7c, C17:1 iso ω9c, and C17:0 iso 3-OH, but showed also slight differences. DNA-DNA hybridizations with type strains of C. gwangjuense, C. formosense, and C. defluvii resulted in values below 70 %. Isolates 91A-561(T) and 91A-576 showed DNA-DNA hybridization values >80 % indicating that they belonged to the same species; but nucleic acid fingerprinting showed that the two isolates represent two different strains. DNA-DNA hybridization results and the differentiating biochemical and chemotaxonomic properties showed, that both strains 91A-561(T) and 91A-576 represent a novel species, for which the name Chryseobacterium geocarposphaerae sp. nov. (type strain 91A-561(T)=LMG 27811(T)=CCM 8488(T)) is proposed. Strains 91A-593(T) and JM-1085(T) represent two additional new species for which we propose the names Chyrseobacterium zeae sp. nov. (type strain JM-1085(T)=LMG 27809(T), =CCM 8491(T)) and Chryseobacterium arachidis sp. nov. (type strain 91A-593(T)=LMG 27813(T), =CCM 8489(T)), respectively.

In vivo fluorescence imaging of exogenous enzyme activity in the gastrointestinal tract.

Exogenous enzymes are administered orally to treat several diseases, such as pancreatic insufficiency and lactose intolerance. Due to the proteinaceous nature of enzymes, they are subject to inactivation and/or digestion in the gastrointestinal (GI) tract. Here we describe a convenient fluorescence-based assay to monitor the activity of therapeutic enzymes in real time in vivo in the GI tract. To establish the proof of principle, the assay was applied to proline-specific endopeptidases (PEPs), a group of enzymes recently proposed as adjuvant therapy for celiac disease (a highly prevalent immunogenetic enteropathy). A short PEP-specific peptide sequence which is part of larger immunotoxic sequences of gluten was labeled with a fluorescent dye and a corresponding quencher. Upon enzymatic cleavage, the fluorescence emission was dequenched and detected with an in vivo imaging system. PEPs originating from Flavobacterium meningosepticum (FM) and Myxococcus xanthus (MX) were evaluated after oral administration in rats. While MX PEP could not cleave the peptide in the stomach, FM PEP showed significant gastric activity reaching 40-60% of the maximal in vivo signal intensity. However, both enzymes produced comparable fluorescence signals in the small intestine. Coadministration of an antacid drug significantly enhanced MX PEP's gastric activity due to increased pH and/or inhibition of stomach proteases. With this simple procedure, differences in the in vivo performance of PEPs, which could not be identified under in vitro conditions, were detected. This imaging assay could be used to study other oral enzymes in vivo and therefore be instrumental in improving their therapeutic efficiency.

Phenylacetic acid, an anti-vaginitis metabolite produced by the vaginal symbiotic bacterium Chryseobacterium gleum.

The human microbiome contains genetic information that regulates metabolic processes in response to host health and disease. While acidic vaginal pH is maintained in normal conditions, the pH level increases in infectious vaginitis. We propose that this change in the vaginal environment triggers the biosynthesis of anti-vaginitis metabolites. Gene expression levels of Chryseobacterium gleum, a vaginal symbiotic bacterium, were found to be affected by pH changes. The distinctive difference in the metabolic profiles between two C. gleum cultures incubated under acidic and neutral pH conditions was suggested to be an anti-vaginitis molecule, which was identified as phenylacetic acid (PAA) by spectroscopic data analysis. The antimicrobial activity of PAA was evaluated in vitro, showing greater toxicity toward Gardnerella vaginalis and Candida albicans, two major vaginal pathogens, relative to commensal Lactobacillus spp. The activation of myeloperoxidase, prostaglandin E2, and nuclear factor-κB, and the expression of cyclooxygenase-2 were reduced by an intravaginal administration of PAA in the vaginitis mouse model. In addition, PAA displayed the downregulation of mast cell activation. Therefore, PAA was suggested to be a messenger molecule that mediates interactions between the human microbiome and vaginal health.

Bacterial siderophores efficiently provide iron to iron-starved tomato plants in hydroponics culture.

Iron is one of the essential elements for a proper plant development. Providing plants with an accessible form of iron is crucial when it is scant or unavailable in soils. Chemical chelates are the only current alternative and are highly stable in soils, therefore, posing a threat to drinking water. The aim of this investigation was to quantify siderophores produced by two bacterial strains and to determine if these bacterial siderophores would palliate chlorotic symptoms of iron-starved tomato plants. For this purpose, siderophore production in MM9 medium by two selected bacterial strains was quantified, and the best was used for biological assay. Bacterial culture media free of bacteria (S) and with bacterial cells (BS), both supplemented with Fe were delivered to 12-week-old plants grown under iron starvation in hydroponic conditions; controls with full Hoagland solution, iron-free Hoagland solution and water were also conducted. Treatments were applied twice along the experiment, with a week in between. At harvest, plant yield, chlorophyll content and nutritional status in leaves were measured. Both the bacterial siderophore treatments significantly increased plant yield, chlorophyll and iron content over the positive controls with full Hoagland solution, indicating that siderophores are effective in providing Fe to the plant, either with or without the presence of bacteria. In summary, siderophores from strain Chryseobacterium C138 are effective in supplying Fe to iron-starved tomato plants by the roots, either with or without the presence of bacteria. Based on the amount of siderophores produced, an effective and economically feasible organic Fe chelator could be developed.

Biodegradation of keratinous waste by Chryseobacterium sp. RBT isolated from soil contaminated with poultry waste.

In the present study, a feather degrading bacterial strain was isolated from poultry waste disposal site, Kolhapur, India. The bacterium was identified as Chryseobacterium sp. RBT using 16S rRNA gene sequence analysis. Chryseobacterium sp. RBT showed rapid hydrolysis of native feathers within 30 h and produced the highest level of keratinase activity (98.3 U/ml). Keratin containing wastes viz. silk, human hair, wool and chicken feathers were tested for keratin degrading ability of the bacterium. Amongst the tested substrates, the Chryseobacterium sp. RBT showed more specificity towards chicken feathers (98.6% degradation) with maximum keratinase activity (98.3 U/ml) and solubilized protein concentration (3.84 mg/ml). Effect of various physico-chemical parameters (temperature, pH, carbon and nitrogen sources) on keratinase production was monitored. The maximum keratinase activity was observed at pH (8.6) and temperature (50 °C). Molasses (1.0% w/v) acted as an inducer and enhanced the keratinolytic activity by two fold, while starch worked as an inhibitor. The goat skin when treated with crude keratinase enzyme (2% v/v), showed complete dehairing within 12 h. Hence, Chryseobacterium sp. RBT shows potential as a candidate for treating the keratinous waste in an ecofriendly manner.

Cellular Response and Molecular Mechanism of Glyphosate Degradation by Chryseobacterium sp. Y16C.

Glyphosate is one of the most widely used herbicides worldwide. Unfortunately, the continuous use of glyphosate has resulted in serious environmental contamination and raised public concern about its impact on human health. In our previous study, Chryseobacterium sp. Y16C was isolated and characterized as an efficient degrader that can completely degrade glyphosate. However, the biochemical and molecular mechanisms underlying its glyphosate biodegradation ability remain unclear. In this study, the physiological response of Y16C to glyphosate stimulation was characterized at the cellular level. The results indicated that, in the process of glyphosate degradation, Y16C induced a series of physiological responses in the membrane potential, reactive oxygen species levels, and apoptosis. The antioxidant system of Y16C was activated to alleviate the oxidative damage caused by glyphosate. Furthermore, a novel gene, goW, was expressed in response to glyphosate. The gene product, GOW, is an enzyme that catalyzes glyphosate degradation, with putative structural similarities to glycine oxidase. GOW encodes 508 amino acids, with an isoelectric point of 5.33 and a molecular weight of 57.2 kDa, which indicates that it is a glycine oxidase. GOW displays maximum enzyme activity at 30 °C and pH 7.0. Additionally, most of the metal ions exhibited little influence on the enzyme activity except for Cu2+. Finally, with glyphosate as the substrate, the catalytic efficiency of GOW was higher than that of glycine, although opposite results were observed for the affinity. Taken together, the current study provides new insights to deeply understand and reveal the mechanisms of glyphosate degradation in bacteria.

Genome features of a novel hydrocarbonoclastic Chryseobacterium oranimense strain and its comparison to bacterial oil-degraders and to other C. oranimense strains.

For the first time, we report the whole genome sequence of a hydrocarbonoclastic Chryseobacterium oranimense strain isolated from Trinidad and Tobago (COTT) and its genes involved in the biotransformation of hydrocarbons and xenobiotics through functional annotation. The assembly consisted of 11 contigs with 2,794 predicted protein-coding genes which included a diverse group of gene families involved in aliphatic and polycyclic hydrocarbon degradation. Comparative genomic analyses with 18 crude-oil degrading bacteria in addition to two C. oranimense strains not associated with oil were carried out. The data revealed important differences in terms of annotated genes involved in the hydrocarbon degradation process that may explain the molecular mechanisms of hydrocarbon and xenobiotic biotransformation. Notably, many gene families were expanded to explain COTT's competitive ability to manage habitat-specific stressors. Gene-based evidence of the metabolic potential of COTT supports the application of indigenous microbes for the remediation of polluted terrestrial environments and provides a genomic resource for improving our understanding of how to optimize these characteristics for more effective bioremediation.