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Applied and Environmental Microbiology Mar 20225-Hydroxypicolinic acid (5HPA), an important natural pyridine derivative, is microbially degraded in the environment. Previously, a gene cluster, , responsible for 5HPA...
The TetR Family Repressor HpaR Negatively Regulates the Catabolism of 5-Hydroxypicolinic Acid in Alcaligenes faecalis JQ135 by Binding to Two Unique DNA Sequences in the Promoter of Operon.
5-Hydroxypicolinic acid (5HPA), an important natural pyridine derivative, is microbially degraded in the environment. Previously, a gene cluster, , responsible for 5HPA degradation, was identified in Alcaligenes faecalis JQ135. However, the transcription regulation mechanism of the cluster is still unknown. In this study, the transcription start site and promoter of the operon was identified. Quantitative reverse transcription-PCR and promoter activity analysis indicated that the transcription of the operon was negatively regulated by a TetR family regulator, HpaR, whereas the transcription of itself was not regulated by HpaR. Electrophoretic mobility shift assay and DNase I footprinting revealed that HpaR bound to two DNA sequences, covering the -35 region and -10 region, respectively, in the promoter region of the operon. Interestingly, the two binding sequences are partially palindromic, with 3 to 4 mismatches and are complementary to each other. 5HPA acted as a ligand of HpaR, preventing HpaR from binding to promoter region and derepressing the transcription of the operon. The study revealed that HpaR binds to two unique complementary sequences of the promoter of the operon to negatively regulate the catabolism of 5HPA. This study revealed that the transcription of the operon was negatively regulated by a TetR family regulator, HpaR. The binding of HpaR to the promoter of the operon has the following unique features: (i) HpaR has two independent binding sites in the promoter of the operon, covering -35 region and -10 region, respectively; (ii) the palindrome sequences of the two binding sites are complementary to each other; and (iii) both of the binding sites include a 10-nucleotide partial palindrome sequence with 3 to 4 mismatches. This study provides new insights into the binding features of the TetR family regulator with DNA sequences.
Topics: Alcaligenes faecalis; Bacterial Proteins; Base Sequence; Binding Sites; Gene Expression Regulation, Bacterial; Operon; Promoter Regions, Genetic
PubMed: 35138929
DOI: 10.1128/aem.02390-21 -
Molecules (Basel, Switzerland) Sep 2021The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this...
The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this research, SeNPs were synthesized by green synthesis using ascorbic acid (AsAc) as a reducing agent and methanolic extract of L. flowers as a stabilizer. Characterization of SeNPs was performed by UV-vis spectrophotometry, infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. SeNPs of 40-60 nm and spherical morphologies were obtained. The antibacterial activity of marigold extracts and fractions was evaluated by disk diffusion methodology. The evaluation of SeNPs at different incubation times was performed through the colony-forming unit (CFU) count, in both cases against , , and bacteria. Partial antibacterial activity was observed with methanolic extracts of marigold leaves and flowers and total inhibition with SeNPs from 2 h for , 1 h for , and 30 min for In addition, SeNPs were found to exhibit antioxidant activity. The results indicate that SeNPs present a potentiated effect of both antimicrobial and antioxidant activity compared to the individual use of marigold extracts or sodium selenite (NaSeO). Their application emerges as an alternative for the control of clinical pathogens.
Topics: Anti-Bacterial Agents; Antioxidants; Bacteria; Calendula; Humans; Nanoparticles; Plant Extracts; Selenium
PubMed: 34641478
DOI: 10.3390/molecules26195929 -
Microorganisms Jan 2022Larvae of the black soldier fly (BSF) are polyphagous feeders and show tremendous bioconversion capabilities of organic matter into high-quality insect biomass....
Larvae of the black soldier fly (BSF) are polyphagous feeders and show tremendous bioconversion capabilities of organic matter into high-quality insect biomass. However, the digestion of lignocellulose-rich palm oil side streams such as palm kernel meal (PKM) is a particular challenge, as these compounds are exceptionally stable and are mainly degraded by microbes. This study aimed to investigate the suitability of BSF larvae as bioconversion agents of PKM. Since the intestinal microbiota is considered to play a key role in dietary breakdown and in increasing digestibility, the bacterial and fungal communities of BSF larvae were characterized in a culture-dependent approach and screened for their putative entomopathogenicity. The lethality of six putative candidates was investigated using intracoelomal injection. In total, 93 isolates were obtained with a bacterial share of 74% that were assigned to the four phyla , , , and . Members of the genera , and are part of the core microbiome, as they were frequently described in the gut of larvae regardless of diet, nutritional composition, or rearing conditions. With 75%, a majority of the fungal isolates belonged to the phylum . We identified several taxa already published to be able to degrade lignocelluloses, including , , yeasts, or filamentous species. The injection assays revealed pronounced differences in pathogenicity against the larvae. While caused no, weak (23.3%), moderate (53.3%), and and high (≥80%) lethality, injection resulted in 100% lethality.
PubMed: 35208774
DOI: 10.3390/microorganisms10020319 -
Microbial Cell Factories Oct 2020Enzymatic quantification of creatinine has become an essential method for clinical evaluation of renal function. Although creatinase (CR) is frequently used for this...
BACKGROUND
Enzymatic quantification of creatinine has become an essential method for clinical evaluation of renal function. Although creatinase (CR) is frequently used for this purpose, its poor thermostability severely limits industrial applications. Herein, we report a novel creatinase from Alcaligenes faecalis (afCR) with higher catalytic activity and lower K value, than currently used creatinases. Furthermore, we developed a non-biased phylogenetic consensus method to improve the thermostability of afCR.
RESULTS
We applied a non-biased phylogenetic consensus method to identify 59 candidate consensus residues from 24 creatinase family homologs for screening afCR mutants with improved thermostability. Twenty-one amino acids of afCR were selected to mutagenesis and 11 of them exhibited improved thermostability compared to the parent enzyme (afCR-M0). Combination of single-site mutations in sequential screens resulted in a quadruple mutant D17V/T199S/L6P/T251C (M4-2) which showed ~ 1700-fold enhanced half-life at 57 °C and a 4.2 °C higher T than that of afCR-M0. The mutant retained catalytic activity equivalent to afCR-M0, and thus showed strong promise for application in creatinine detection. Structural homology modeling revealed a wide range of potential molecular interactions associated with individual mutations that contributed to improving afCR thermostability.
CONCLUSIONS
Results of this study clearly demonstrated that the non-biased-phylogenetic consensus design for improvement of thermostability in afCR is effective and promising in improving the thermostability of more enzymes.
Topics: Alcaligenes faecalis; Amino Acid Substitution; Enzyme Stability; Kinetics; Molecular Dynamics Simulation; Mutagenesis, Site-Directed; Phylogeny; Protein Engineering; Temperature; Ureohydrolases
PubMed: 33069232
DOI: 10.1186/s12934-020-01451-9 -
Insects Aug 2020Stingless bee honey (SBH) is an astounding 'miracle liquid' with countless medicinal properties for various diseases such as gastroenteritis, cataracts, as well as for...
Stingless bee honey (SBH) is an astounding 'miracle liquid' with countless medicinal properties for various diseases such as gastroenteritis, cataracts, as well as for wound-healing. However, knowledge regarding it is still rather scarce. Henceforth, it is intriguing for us to contemplate on the less-studied stingless bee and its honey in particular. First and foremost, the antimicrobial ability of honey from eight different stingless bee species was tested to further proven its health benefit. honey showed the highest antimicrobial activity with inhibition against five bacteria; , , , and . The next aim of our study is to characterize their honey bacterial community via the use of 16S rRNA amplicon sequencing technology. A total of eight bacterial phyla, 71 families, 155 genera and 70 species were identified from our study and two of the stingless bee species honey were determined to have the highest bacterial diversity compared to other six stingless bee species, namely and . Furthermost, was thought to be the native dominant bacteria of SBH due to its predominant presence throughout all studied species. The aforementioned SBH's antimicrobial results and characterization study of its bacterial diversity are hoped to carve the pathway towards extending its probiotic ability into our everyday lives.
PubMed: 32759701
DOI: 10.3390/insects11080500 -
PeerJ 2023has a well-established negative impact on rice yield in transplanted and direct-seeded rice, resulting in yield losses of up to 20 to 90 percent. Studies were...
has a well-established negative impact on rice yield in transplanted and direct-seeded rice, resulting in yield losses of up to 20 to 90 percent. Studies were undertaken to isolate potential native strains of bio-control agents to manage the devastating Rice Root Knot Nematode (). Eighteen bacterial strains and eleven fungal strains were isolated from the rhizosphere of crops like rice, okra, ash gourd, chili, beans and cucumber, enveloping diverse soil types from the Upper Brahmaputra Valley region of Assam. Six bacterial strains were gram-positive according to morphological results, while twelve others stained negatively. Fifteen bacteria were rod-shaped, two were coccus and one was diplococcus, and all the bacterial isolates showed signs of movement. All the bacterial strains exhibited positivity for gelatin hydrolysis and catalase test. Seven bacteria showed positive, while eleven showed negative reactions to possess the ability to deduce carbon and energy from citrate. The study of the efficacy of the twenty-nine bacterial and fungal isolates tested against second-stage juveniles (J) of revealed that all the bacterial and fungal isolates potentially inhibited the test organism and caused significant mortality over sterile water treatment. The promising bacterial and fungal isolates that exhibited mortality above 50% were identified as BSH8, BTS4, BTS5, BJA15, FJB 11 and FSH5. The strain BSH8 exhibited the best result of mortality, with 80.79% mortality against J of . The strain BTS4 and BTS5 expressed mortality of 71.29% and 68.75% under conditions and were significant. The effective and promising bioagents were identified using the 16 S rRNA sequencing as (BSH8), (BTS4), (BTS5), (BJA15), (FSH5) and (FJB11). These results indicated the microorganism's potential against and its potential for successful biological implementation. Further, the native strains could be tested against various nematode pests of rice in field conditions. Its compatibility with various pesticides and the implication of the potential strains in integrated pest management can be assessed.
Topics: Animals; Tylenchoidea; Oryza; Soil; Pest Control; Pesticides
PubMed: 37529212
DOI: 10.7717/peerj.15779 -
Journal of Bacteriology Aug 2019Picolinic acid (PA) is a natural toxic pyridine derivative. Microorganisms can degrade and utilize PA for growth. However, the full catabolic pathway of PA and its...
Picolinic acid (PA) is a natural toxic pyridine derivative. Microorganisms can degrade and utilize PA for growth. However, the full catabolic pathway of PA and its physiological and genetic foundation remain unknown. In this study, we identified a gene cluster, designated , responsible for the degradation of PA from JQ135. Our results suggest that PA degradation pathway occurs as follows: PA was initially 6-hydroxylated to 6-hydroxypicolinic acid (6HPA) by PicA (a PA dehydrogenase). 6HPA was then 3-hydroxylated by PicB, a four-component 6HPA monooxygenase, to form 3,6-dihydroxypicolinic acid (3,6DHPA), which was then converted into 2,5-dihydroxypyridine (2,5DHP) by the decarboxylase PicC. 2,5DHP was further degraded to fumaric acid through PicD (2,5DHP 5,6-dioxygenase), PicE (-formylmaleamic acid deformylase), PicF (maleamic acid amidohydrolase), and PicG (maleic acid isomerase). Homologous gene clusters with diverse organizations were found to be widely distributed in -, -, and Our findings provide new insights into the microbial catabolism of environmental toxic pyridine derivatives. Picolinic acid is a common metabolite of l-tryptophan and some aromatic compounds and is an important intermediate in organic chemical synthesis. Although the microbial degradation/detoxification of picolinic acid has been studied for over 50 years, the underlying molecular mechanisms are still unknown. Here, we show that the gene cluster is responsible for the complete degradation of picolinic acid. The gene cluster was found to be widespread in other -, -, and These findings provide a new perspective for understanding the catabolic mechanisms of picolinic acid in bacteria.
Topics: Alcaligenes faecalis; Bacterial Proteins; Biodegradation, Environmental; Metabolic Networks and Pathways; Mixed Function Oxygenases; Multigene Family; Oxidoreductases; Picolinic Acids
PubMed: 31160400
DOI: 10.1128/JB.00077-19 -
Journal of Fungi (Basel, Switzerland) Jun 2022Simultaneous treatment with antagonistic bacteria (SF14), (ACBC1), and the food additive sodium bicarbonate (SBC) to control post-harvest brown rot disease caused by ,...
Simultaneous treatment with antagonistic bacteria (SF14), (ACBC1), and the food additive sodium bicarbonate (SBC) to control post-harvest brown rot disease caused by , and their effect on the post-harvest quality of nectarines were evaluated. Four concentrations of SBC (0.5, 2, 3.5, and 5%) were tested. Results showed that bacterial antagonists displayed remarkable compatibility with different concentrations of SBC and that their viability was not affected. The results obtained in vitro and in vivo bioassays showed a strong inhibitory effect of all treatments. The combination of each bacterial antagonist with SBC revealed a significant improvement in their biocontrol efficacies. The inhibition rates of mycelial growth ranged from 60.97 to 100%. These results also indicated that bacterial antagonists (SF14 or ACBC1) used at 1 × 10 CFU/ mL in combination with 2, 3.5, or 5% SBC significantly improved the control of by inhibiting the germination of spores. Interestingly, disease incidence and lesion diameter in fruits treated with SF14, ACBC1 alone, or in combination with SBC were significantly lower than those in the untreated fruits. In vivo results showed a significant reduction in disease severity ranging from 9.27 to 64.83% compared to the untreated control, while maintaining the appearance, firmness, total soluble solids (TSS), and titratable acidity (TA) of fruits. These results suggested that the improved disease control by the two antagonistic bacteria was more likely due to the additional inhibitory effects of SBC on the mycelial growth and spore germination of the pathogenic fungus. Overall, the combination of both bacteria with SBC provided better control of brown rot disease. Therefore, a mixture of different management strategies can effectively control brown rot decay on fruits.
PubMed: 35736119
DOI: 10.3390/jof8060636 -
International Journal of Biological... May 2024The potential to degrade ochratoxin A (OTA), a highly poisonous mycotoxin, was investigated in cultures from Alcaligenes-type strains. Genome sequence analyses from...
The potential to degrade ochratoxin A (OTA), a highly poisonous mycotoxin, was investigated in cultures from Alcaligenes-type strains. Genome sequence analyses from different Alcaligenes species have permitted us to demonstrate a direct, causal link between the gene coding a known N-acyl-L-amino acid amidohydrolase from A. faecalis (AfOTH) and the OTA-degrading activity of this bacterium. In agreement with this finding, we found the gene coding AfOTH in two additional species included in the Alcaligenes genus, namely, A. pakistanensis, and A. aquatilis, which also degraded OTA. Notably, A. faecalis subsp. faecalis DSM 30030 was able to transform OTα, the product of OTA hydrolysis. AfOTH from A. faecalis subsp. phenolicus DSM 16503 was recombinantly over-produced and enzymatically characterized. AfOTH is a Zn-containing metalloenzyme that possesses structural features and conserved residues identified in the M20D family of enzymes. AfOTH is a tetramer in solution that shows both aminoacylase and carboxypeptidase activities. Using diverse potential substrates, namely, N-acetyl-L-amino acids and carbobenzyloxy-L-amino acids, a marked preference towards C-terminal Phe and Tyr residues could be deduced. The structural basis for this specificity has been determined by in silico molecular docking analyses. The amidase activity of AfOTH on C-terminal Phe residues structurally supports its OTA and OTB degradation activity.
Topics: Ochratoxins; Alcaligenes; Amidohydrolases; Substrate Specificity; Amino Acid Sequence; Structure-Activity Relationship
PubMed: 38574921
DOI: 10.1016/j.ijbiomac.2024.131342 -
Case Reports in Medicine 2022() is a Gram-negative rod rarely isolated as an infective bacterium worldwide. The first cases of infections caused by this microorganism, such as pneumonia, soft...
() is a Gram-negative rod rarely isolated as an infective bacterium worldwide. The first cases of infections caused by this microorganism, such as pneumonia, soft tissue infections, urinary tract infections, bacteremia, and meningitis, date back more than 40 years and are almost entirely in newborns and immunosuppressed hosts. Optimal antibiotic therapy for has not been well established in the literature. We report a case of an immunocompetent patient in Colombia who had meningitis due to after a dental procedure. It is important to know about this microorganism that nowadays could be considered a potentially emerging pathogen in immunocompetent adults.
PubMed: 36092309
DOI: 10.1155/2022/1559360