The aim of this work is to evaluate textile dyes degradation by novel bacterial strain isolated from the waste disposal sites of local textile industries. Detailed taxonomic studies identified the ...organisms as
Pseudomonas species and designated as strain
Pseudomonas sp. SUK1. The isolate was able to decolorize sulfonated azo dye (Reactive Red 2) in a wide range (up to 5
g
l
−1), at temperature 30
°C, and pH range 6.2–7.5 in static condition. This isolate also showed decolorization of the media containing a mixture of dyes. Measurements of COD were done at regular intervals to have an idea of mineralization, showing 52% reduction in the COD within 24
h. Induction in the activity of lignin peroxidase and azoreductase was observed during decolorization of Reactive Red 2 in the batch culture, which represented their role in degradation. The biodegradation was monitored by UV–vis, IR spectroscopy, HPLC. The final product, 2-naphthol was characterized by GC-mass spectroscopy. The phytotoxicity study revealed the degradation of Reactive Red 2 into non-toxic product by
Pseudomonas sp. SUK1.
Kocuria rosea (MTCC 1532) showed 100% decolorization of methyl orange (50
mg
l
−1) under static condition. The optimum pH and temperature for dye decolorization was 6.8 and 30
°C, respectively. The
...K. rosea (MTCC 1532) showed maximum decolorization of methyl orange when growth medium containing yeast extract as compared to other substrates. The culture exhibited significant ability to decolorize repeated additions of dye, with reduction in time up to 12
h at eighth dye aliquot addition. Significant induction of reductases (NADH-DCIP reductase and azoreductase) suggests its involvement in decolorization of methyl orange. The metabolites formed after decolorization of methyl orange, such as 4-amino sulfonic acid and N,N′-dimethyl
p-phenyldiamine were characterized using FTIR and MS. Phytotoxicity and microbial toxicity study showed the methyl orange was toxic and metabolites obtained after its decolorization was nontoxic for experimental plants (
Triticum aestivum and
Phaseolus mungo) and bacteria (
K. rosea,
Pseudomonas aurugenosa and
Azatobacter vinelandii).
A microbial consortium DAS consisting three bacterial sp. originally obtained from dye contaminated sites of Solapur, India was selected because it was capable of decolorizing textile effluent and ...dye faster than the individual bacteria under static conditions. Identification of the isolates by 16S rRNA techniques revealed the isolates to be
Pseudomonas species. The concerted metabolic activity of these isolates led to complete decolorization of textile effluent as well as Reactive Orange 16 (100
mg
l
−1) within 48-h at pH 7 and 30
°C. Studies involving Reactive Orange 16 (RO16) dye were carried with the bacterial consortium DAS to elucidate the mechanism of biodegradation. Induction of the laccase and reductase enzyme during RO16 decolorization indicated their role in biodegradation. The biodegradation of RO16 was monitored by using IR spectroscopy, HPLC and GC–MS analysis. Cytotoxicity, genotoxicity and phytotoxicity studies carried out before and after decolorization of the textile effluent revealed the nontoxic nature of the biotreated sample.
Colistin is the last drug option for the treatment of MDR Gram-negative bacterial infections. Several types of resistance to colistin have been identified, including hetero-resistance, which has been ...observed in several Gram-negative pathogens. During a routine surveillance project on antimicrobial resistance, we found abnormal colistin-resistant Enterobacter asburiae and Enterobacter cloacae isolates. E. cloacae is an intestinal commensal bacterium and a well-known opportunistic nosocomial pathogen.
To characterize the molecular mechanism of colistin hetero-resistance in Enterobacter spp.
Several approaches (WGS, transposome mutagenesis and RT-PCR analysis) were used to discover the molecular mechanism of colistin hetero-resistance.
Genomic analysis of mutant clones generated by transposome mutagenesis suggests that hetero-resistance is linked with overexpression of the acrAB-tolC efflux pump. Transcriptional analysis further found that naturally elevated soxRS triggers the induction of the acrAB-tolC efflux pump proteins followed by the development of colistin hetero-resistance in E. asburiae and E. cloacae. Transcriptional analysis results were further verified as demonstrating the development of hetero-resistance in colistin-susceptible strains by plasmid-based overexpression of soxRS.
Our observations highlight the importance of such findings, which previously were only superficially described because of the challenges associated with their detection, in the context of common modes of colistin resistance in Gram-negative bacteria. This study constitutes a unique demonstration of efflux-based high-level colistin hetero-resistance, controlled by a soxRS regulator in Gram-negative bacteria.
Klebsiella pneumoniae
is a well-studied human pathogen for which antimicrobial resistant and hypervirulent clones have emerged globally.
K. pneumoniae
is also present in a variety of environmental ...niches, but currently there is a lack of knowledge on the occurrence and characteristics of
K. pneumoniae
from non-human sources. Certain environmental niches, e.g., animals, may be associated with high
K. pneumoniae
abundance, and these can constitute a reservoir for further transmission of strains and genetic elements. The aim of this study was to explore and characterize
K. pneumoniae
from healthy broilers and turkeys. A total of 511 cecal samples (broiler
n
= 356, turkey
n
= 155), included in the Norwegian monitoring program for antimicrobial resistance (AMR) in the veterinary sector (NORM-VET) in 2018, were screened for
K. pneumoniae
by culturing on SCAI agar.
K. pneumoniae
was detected in 207 (40.5%) samples. Among the broiler samples, 25.8% were positive for
K. pneumoniae
, in contrast to turkey with 74.2% positive samples (
p
< 0.01). Antibiotic susceptibility testing was performed, in addition to investigating biofilm production. Whole genome sequencing was performed on 203
K. pneumoniae
isolates, and analysis was performed utilizing comparative genomics tools. The genomes grouped into 66 sequence types (STs), with ST35, ST4710 and ST37 being the most prevalent at 13.8%, 7.4%, and 5.4%, respectively. The overall AMR occurrence was low, with only 11.3% of the isolates showing both pheno- and genotypic resistance. Genes encoding aerobactin, salmochelin or yersiniabactin were detected in 47 (23.2%) genomes. Fifteen hypervirulent genomes belonging to ST4710 and isolated from turkey were identified. These all encoded the siderophore virulence loci
iuc5
and
iro5
on an IncF plasmid. Isolates from both poultry species displayed good biofilm-forming abilities with an average of OD
595
0.69 and 0.64. To conclude, the occurrence of
K. pneumoniae
in turkey was significantly higher than in broiler, indicating that turkey might be an important zoonotic reservoir for
K. pneumoniae
compared to broilers. Furthermore, our results show a highly diverse
K. pneumoniae
population in poultry, low levels of antimicrobial resistance, good biofilm-forming abilities and a novel hypervirulent ST4710 clone circulating in the turkey population.
Abstract
Improvements in cost and speed of next generation sequencing (NGS) have provided a new pathway for delivering disease diagnosis, molecular typing, and detection of antimicrobial resistance ...(AMR). Numerous published methods and protocols exist, but a lack of harmonisation has hampered meaningful comparisons between results produced by different methods/protocols vital for global genomic diagnostics and surveillance. As an exemplar, this study evaluated the sensitivity and specificity of five well-established in-silico AMR detection software where the genotype results produced from running a panel of 436
Escherichia coli
were compared to their AMR phenotypes, with the latter used as gold-standard. The pipelines exploited previously known genotype–phenotype associations. No significant differences in software performance were observed. As a consequence, efforts to harmonise AMR predictions from sequence data should focus on: (1) establishing universal minimum to assess performance thresholds (e.g. a control isolate panel, minimum sensitivity/specificity thresholds); (2) standardising AMR gene identifiers in reference databases and gene nomenclature; (3) producing consistent genotype/phenotype correlations. The study also revealed limitations of in-silico technology on detecting resistance to certain antimicrobials due to lack of specific fine-tuning options in bioinformatics tool or a lack of representation of resistance mechanisms in reference databases. Lastly, we noted user friendliness of tools was also an important consideration. Therefore, our recommendations are timely for widespread standardisation of bioinformatics for genomic diagnostics and surveillance globally.
Agrobacterium radiobacter MTCC 8161 completely decolorized the Crystal Violet with 8 hr （10 mg/L） at static anoxic conditions. The decreased decolorization capability by A. radiobacter was observed, ...when the Crystal Violet concentration was increased from 10 to 100 mg/L. Semi-synthetic medium containing 1% yeast extract and 0.1% NH4C1 has shown 100% decolorization of Crystal Violet within 5 hr. A complete degradation of Crystal Violet by A. radiobacter was observed up to 7 cycles of repeated addition （10 rag/L）. When the effect of increasing inoculum concentration on decolorization of Crystal Violet （100 mg/L） was studied, maximum decolorization was observed with 15% inoculum concentration. A significant increase in the activities of laccase （184%） and aminopyrine N-demethylase （300%） in cells obtained after decolorization indicated the involvement of these enzymes in decolorization process. The intermediates formed during the degradation of Crystal Violet were analyzed by gas chromatography and mass spectroscopy （GC/MS）. It was detected the presence of N,N,N＇,N＂-tetramethylpararosarfiline, IN, N-dimethylaminophenyl N-methylaminophenyl benzophenone, N, N-dimethylaminobenzaldehyde, 4-methyl amino phenol and phenol. We proposed the hypothetical metabolic pathway of Crystal Violet biodegradation by A. radiobacter. Phytotoxicity and microbial toxicity study showed that Crystal Violet biodegradation metabolites were less toxic to bacteria （A. radiobacter, P. aurugenosa and A. vinelandii） contributing to soil fertility and for four kinds of plants （Sorghum bicolor, Vigna radiata, Lens culinaris and Triticum aestivum） which are most sensitive, fast growing and commonly used in Indian agriculture.
•Mechanism of colistin resistance in the frequent pathogen Proteus vulgaris is unknown.•Role of aminoarabinose in colistin resistance in P. vulgaris is demonstrated.•WGS and in vitro analysis of an ...atypical strain improve knowledge of this species.•Highlights the potential role of some genes in colistin resistance.
Colistin has become a last-line antibiotic for the treatment of multidrug-resistant bacterial infections; however, resistance to colistin has emerged in recent years. Some bacteria, such as Proteus and Serratia spp., are intrinsically resistant to colistin although the exact mechanism of resistance is unknown. Here we identified the molecular support for intrinsic colistin resistance in Proteus spp. by comparative genomic, transcriptomic and proteomic analyses of colistin-susceptible (CSUR P1868_S) and colistin-resistant (CSUR P1867_R) strains of an atypical Proteus vulgaris. A significant difference in outer membrane glycoside structures in both strains that was corroborated by MALDI-TOF/MS analysis was found, which showed an absence of 4-amino-4-deoxy-l-arabinose (L-Ara4N) in the outer membrane lipid A moiety of the susceptible strain. Comparative genomic analysis with other resistant strains of P. vulgaris available in a local database found a mutation in the arnBCADTEF operon of the susceptible strain. Transcriptomic analysis of genes belonging to the arnBCADTEF operon showed a significant decrease in mRNA expression level of these genes in the susceptible strain, supporting addition of L-Ara4N in the outer membrane lipid A moiety as an explanation for colistin resistance. Insertion of the arnD gene that was suggested to be altered in the susceptible strain by in silico analysis led to a 16-fold increase of colistin MIC in the susceptible strain, confirming its role in colistin resistance in this species. Here we show that constitutive activation of the arn operon and addition of L-Ara4N is the main molecular mechanism of colistin resistance in P. vulgaris.
This study examines how household chaos and unmanaged parental stress are associated with and contribute to variance in markers of the home food environment (family meal frequency, perceived barriers ...to cooking, healthful home food availability). Obtaining a better understanding of these relationships could guide more effective family-based interventions to promote healthful home food environments.
The analytic sample included 819 households with children in the population-based Project EAT-IV cohort with survey data from 2015 to 2016. Multiple linear regression was used to generate means and 95% confidence intervals of home food environment variables, and estimates for the contribution of household chaos (defined by frenetic activity, loud noises and disorder), and quartiles of unmanaged parental stress (ratio of perceived stress and ability to manage stress). Model fit was also examined.
Both household chaos and quartiles of unmanaged parental stress were independently and inversely associated with family meal frequency (p's < 0.001) and positively associated with perceived mealtime preparation barriers (p's < 0.001). Unmanaged parental stress was also inversely associated with healthful home food availability (p = 0.004). Models including demographic characteristics, household chaos scores, and quartiles of unmanaged parental stress index showed significantly improved model fit for all outcomes compared to less comprehensive models. Among families with high chaos, those having 7 + family meals/week were significantly more likely to have lower mealtime preparation barrier scores, younger children and higher healthful home food availability scores than families eating together less often.
Interventions to assist with parental management of stress and chaos within the home environment (e.g., establishing routines) may increase family meal frequency and the quality of children's home food environments.
Bacillus sp. ADR secretes an extracellular laccase in nutrient broth, and this enzyme was purified up to 56-fold using acetone precipitation and DEAE-cellulose anion exchange chromatography. The ...molecular weight of purified laccase was estimated to be 66
kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified laccase oxidized 2,6-dimethoxy phenol,
o-tolidine, hydroquinone,
l-DOPA and guaiacol. The optimum pH for oxidation of
o-tolidine, 2,6-dimethoxy phenol and guaiacol were 3.0, 4.0 and 5.0, respectively. The purified laccase contained 2.7
mol/mol of copper. The laccase was stable up to 40
°C and within the pH range of 7.0–9.0. Well-known inhibitors of multicopper oxidases such as, sodium azide,
l-cysteine and dithiothreitol showed significant inhibition of laccase activity. The purified enzyme decolorized structurally different azo dyes with variable decolorization rates and efficiencies of 68–90%. This study is useful for understanding the precise use of
Bacillus sp. ADR in the decolorization of textile dyes containing industrial wastewater.
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