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Journal of Food Protection Apr 2023In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living...
In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living conditions occur in stagnant water. The present study aimed to identify bacteria that cause foodborne diseases or are associated with human diseases. For molecular identification, based on the sequential analysis by 16S rRNA or rpoD was conducted on all isolates obtained from bullfrog. A total of 91 bacterial isolates were obtained from bullfrogs; 14 genera and 23 species were identified, including Acinetobacter johnsonii 16.5%; Aeromonas media 14.3%; Aeromonas veronii 13.2%; Providencia rettgeri 7.7%; Citrobacter freundii 6.6%; Aeromonas caviae 4.4%; Aeromonas hydrophila and Elizabethkingia ursingii 3.3%; Pseudomonas stutzeri, Raoultella ornithinolytica, and Shewanella putrefaciens 2.2%; Acinetobacter guillouiae, Acinetobacter pseudolwoffii, Citrobacter portucalensis, Citrobacter werkmanii, Edwardsiella anguillarum, Klebsiella michiganensis, Kluyvera intermedia, Kocuria rosea, Myroides odoratimimus, Myroides odoratus, Proteus sp., and Proteus hauseri 1.1%. In this study, 49.4% of the isolates obtained cause foodborne disease, 19.8% are bacteria that play an important role in the spoilage of food, 5.5% of isolates have nosocomial significance, 13.2% of bacteria are considered to be pollutants of the ecosystem, and in the case of A. salmonicida and Edwardsiella anguillarum (12.1%) to have a negative impact on aquaculture. Acinetobacter pseudolwoffii and Citrobacter portucalensis have not been reported to cause disease. Lastly of these isolates, 97.8% (89/91) can cause disease by food consumption or by direct contact for immunocompromised persons. The presence of these bacteria in bullfrogs represents a significant problem for human health. There is evidence that these microorganisms are pathogenic and frogs may also be reservoirs.
Topics: Animals; Humans; Rana catesbeiana; Ecosystem; RNA, Ribosomal, 16S; Foodborne Diseases
PubMed: 36948016
DOI: 10.1016/j.jfp.2023.100067 -
Microbial Cell Factories Mar 2023ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative that is mainly produced by filamentous and aerobic bacteria Streptomyces albulus. During ε-PL...
BACKGROUND
ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative that is mainly produced by filamentous and aerobic bacteria Streptomyces albulus. During ε-PL biosynthesis, a large amount of ATP is used for the polymerization of L-lysine. A shortage of intracellular ATP is one of the major factors limiting the increase in ε-PL production. In previous studies, researchers have mainly tried to increase the oxygen supply to enhance intracellular ATP levels to improve ε-PL production, which can be achieved through the use of two-stage dissolved oxygen control, oxygen carriers, heterologous expression of hemoglobin, and supplementation with auxiliary energy substrates. However, the enhancement of the intracellular ATP supply by constructing an ATP regeneration system has not yet been considered.
RESULTS
In this study, a polyphosphate kinase (PPK)-mediated ATP regeneration system was developed and introduced into S. albulus to successfully improve ε-PL production. First, polyP:AMP phosphotransferase (PAP) from Acinetobacter johnsonii was selected for catalyzing the conversion of AMP into ADP through an in vivo test. Moreover, three PPKs from different microbes were compared by in vitro and in vivo studies with respect to catalytic activity and polyphosphate (polyP) preference, and PPK2B from Corynebacterium glutamicum was used for catalyzing the conversion of ADP into ATP. As a result, a recombinant strain PL05 carrying coexpressed pap and ppk2B for catalyzing the conversion of AMP into ATP was constructed. ε-PL production of 2.34 g/L was achieved in shake-flask fermentation, which was an increase of 21.24% compared with S. albulus WG608; intracellular ATP was also increased by 71.56%. In addition, we attempted to develop a dynamic ATP regulation route, but the result was not as expected. Finally, the conditions of polyP addition were optimized in batch and fed-batch fermentations, and the maximum ε-PL production of strain PL05 in a 5-L fermenter was 59.25 g/L by fed-batch fermentation, which is the highest ε-PL production reported in genetically engineered strains.
CONCLUSIONS
In this study, we proposed and developed a PPK-mediated ATP regeneration system in S. albulus for the first time and significantly enhanced ε-PL production. The study provides an efficient approach to improve the production of not only ε-PL but also other ATP-driven metabolites.
Topics: Polylysine; Fermentation; Adenosine Triphosphate; Regeneration
PubMed: 36918890
DOI: 10.1186/s12934-023-02057-7 -
Plant Physiology and Biochemistry : PPB Mar 2023Cumulative microbial respiration reflects microbial activities and their potential to support plant growth, where salt tolerant rhizobacteria can optimize their...
Cumulative microbial respiration reflects microbial activities and their potential to support plant growth, where salt tolerant rhizobacteria can optimize their respiration, and ensure plant survival under salt stress. We evaluated cumulative microbial respiration of different salt tolerant rhizobacterial strains at different salinity levels, and checked their ability to sustain plant growth under natural saline conditions by using maize as test crop. Our results revealed that at the highest EC level (10 dS m), strain 'SUA-14' performed significantly better, and exhibited the greatest cumulative respiration (4.2 fold) followed by SHM-13 (3.8 fold), as compared to un-inoculated control. Moreover, results of the field trial indicated a similar trend, where significant improvements in shoot fresh weight (59%), root fresh weight (80%), shoot dry weight (56%), root dry weight (1.4 fold), leaf area (1.9 fold), straw yield (41%), cob diameter (33%), SPAD value (84%), yield (99%), relative water contents (91%), flavonoid (55%), 1000 grain weight (∼100%), soluble sugars (41%) and soluble proteins (45%) were observed due to inoculation of strain 'SUA-14' as compared to un-inoculated control. Similarly, substantial decline in leaf Na (34%), Na/K ratio (69%), electrolyte leakage (8%), catalase (54%), peroxidase (73%), and HO (50%) activities were observed after inoculation of 'SUA-14' with a concomitant increment in the leaf K contents (70%) under salinity stress than un-inoculated control. Hence, among all the tested rhizobacterial isolates, 'SUA-14' served as the most efficient strain in alleviating the detrimental impacts of salinity on maize growth and yield. The 16S rRNA sequencing identified it as Acinetobacter johnsonii.
Topics: Zea mays; Soil Microbiology; RNA, Ribosomal, 16S; Hydrogen Peroxide; Salt Stress; Salinity
PubMed: 36689831
DOI: 10.1016/j.plaphy.2023.01.037 -
Journal of Clinical Medicine Jan 2023(1) Background: Non-obstructive azoospermia (NOA) is a complex multifactorial disease and the causes of most NOA cases remain unknown. (2) Methods: Here, we performed...
(1) Background: Non-obstructive azoospermia (NOA) is a complex multifactorial disease and the causes of most NOA cases remain unknown. (2) Methods: Here, we performed comprehensive clinical analyses and gut microbial profiling using shotgun metagenomic sequencing in patients with NOA and control individuals. (3) Results: The gut microbial alpha and beta diversity significantly differed between patients with NOA and controls. Several microbial strains, including and , were significantly more abundant in the NOA group, whereas and sp. were enriched in the control group. Moreover, functional pathway analysis suggested that the altered microbiota in NOA suppressed the carbohydrate metabolism pathway, while amino acid metabolism and methane metabolism pathways were enhanced. We observed that the differential microbial species, such as , had a strong correlation with clinical parameters, including age, body mass index, testosterone, and follicle-stimulating hormone. Communication and interplay among microbial genera were significantly increased in NOA than in the control group. (4) Conclusions: Altered microbial composition and functional pathways in the NOA group were revealed, which highlight the utility of gut microbiota in understanding microbiota-related pathogenesis of NOA and might be helpful to the clinical management of NOA.
PubMed: 36675631
DOI: 10.3390/jcm12020701 -
Nanomaterials (Basel, Switzerland) Nov 2022The interaction between nanoplastics and bacteria remains still largely unclear. In this study, we determined the effect of nanopolystyrene particle (NP) on a bacterial...
The interaction between nanoplastics and bacteria remains still largely unclear. In this study, we determined the effect of nanopolystyrene particle (NP) on a bacterial pathogen of Acinetobacter johnsonii AC15. Scanning electron microscopy (SEM) analysis indicated the aggregation of NPs from 10 μg/L to 100 μg/L on surface of A. johnsonii AC15, suggesting that A. johnsonii AC15 acted as the vector for NPs. Exposure to 100−1000 μg/L NPs increased the growth and colony-forming unit (CFU) of A. johnsonii AC15. In addition, exposure to 100−1000 μg/L NPs enhanced the amount of formed biofilm of A. johnsonii AC15. Alterations in expressions of 3 survival-related (zigA, basD, and zur), 5 biofilm formation-related (ompA, bap, adeG, csuC, and csuD), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were observed after exposure to 1000 μg/L NPs. Moreover, both CFU and survival rate of A. johnsonii AC15 in normal human serum (NHS) were significantly increased by 1−1000 μg/L NPs, suggesting the enhancement in serum resistance of Acinetobacter pathogen by NPs. In the NHS, expressions of 3 survival-related (zigA, basD, and zur), 9 biofilm formation-related (ompA, bap, adeF, adeG, csuA/B, csuC, csuD, csuE, and hlyD), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were affected by 1000 μg/L NPs. Expressions of 1 survival-related (zigA), 5 biofilm formation-related (bap, adeG, csuC, csuD, and csuE), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were also altered by 10 μg/L NPs after the addition of NHS. Therefore, exposure to NPs in the range of μg/L has the potential to enhance bacterial virulence by increasing their growth, biofilm formation, and serum resistance.
PubMed: 36500844
DOI: 10.3390/nano12234222 -
Polish Journal of Microbiology Dec 2022Rapid detection of bloodstream pathogens would greatly facilitate clinicians to make precise antimicrobial treatment in patients with bacteremia. In this study, 114...
Rapid detection of bloodstream pathogens would greatly facilitate clinicians to make precise antimicrobial treatment in patients with bacteremia. In this study, 114 plasma samples were collected from patients with identified or suspected bacteremia, and pathogens were detected by the conventional blood culture (BC) and cell-free DNA metagenomics next-generation sequencing (cfDNA mNGS). The present study indicated that 76% (38/50) of positive conventional blood culture (BC group) patients were positively detected by cfDNA mNGS, and only 4% were mismatched between cfDNA mNGS and conventional bacteria culture. Pathogens in 32.8% of suspected bacteremia patients with negative conventional blood culture (BC group) were determined accurately by cfDNA mNGS combined with analyzing the patients' clinical manifestations. and were the most detected pathogens in identified bacteremia patients by cfDNA mNGS. 76.2% (16/21) of and 92.3% (12/13) of in bacteremia patients were identified by conventional blood cultures that were also detected by cfDNA mNGS. This study demonstrated that genomic coverage of and were more often detected in BC group patients and genomic coverage of and sp. KCTC 42545 was more often detected in BC group patients. In conclusion, cfDNA mNGS could rapidly and precisely provide an alternative detection method for the diagnosis of bacteremia.
Topics: Humans; Escherichia coli; High-Throughput Nucleotide Sequencing; Genomics; Bacteremia; Cell-Free Nucleic Acids; Klebsiella pneumoniae; Sensitivity and Specificity
PubMed: 36369999
DOI: 10.33073/pjm-2022-043 -
Scientific Reports Oct 2022Mountain regions in Poland are among the most frequently visited tourist destinations, causing a significant anthropogenic pressure put on the local rivers. In this...
Mountain regions in Poland are among the most frequently visited tourist destinations, causing a significant anthropogenic pressure put on the local rivers. In this study, based on numbers of 9 microorganisms, content of 17 antibiotics and 17 physicochemical parameters, we determined a pollution gradient in six sites along Białka, a typical mountain river in southern Poland. The E.coli/Staphylococcus ratio varied evidently between polluted and non-polluted sites, indicating that the possible utility of this parameter in assessing the anthropogenic impact on river ecosystems is worth further investigation. Then, using next generation sequencing, we assessed the changes in bacterial community structure and diversity as a response to the pollution gradient. Proteobacteria and Bacteroidetes were the most abundant phyla in the majority of samples. Actinobacteria were the most abundant in the most pristine (groundwater) sample, while Firmicutes and Verrucomicrobia were more prevalent in polluted sites. Bacterial diversity at various levels increased with water pollution. Eleven bacterial genera potentially containing pathogenic species were detected in the examined samples, among which Acinetobacter, Rhodococcus, and Mycobacterium were the most frequent. At the species level, Acinetobacter johnsonii was most prevalent potential pathogen, detected in all surface water samples, including the pristine ones. Two bacterial taxa-genus Flectobacillus and order Clostridiales showed very distinct variation in the relative abundance between the polluted and non-polluted sites, indicating their possible potential as biomarkers of anthropogenic impact on mountain river waters.
Topics: Rivers; Ecosystem; Bacteria; Water Pollution; Bacteroidetes
PubMed: 36307524
DOI: 10.1038/s41598-022-22642-x -
Plants (Basel, Switzerland) Oct 2022The therapeutic importance of in folk medicine for the treatment of several common human diseases has led researchers to conduct phytochemical and pharmacological...
The therapeutic importance of in folk medicine for the treatment of several common human diseases has led researchers to conduct phytochemical and pharmacological studies on extracts from various parts of the plant. In the current study, the phytochemical composition of the methanolic fruit extract was characterized, and its antimicrobial activity was evaluated together with the cytotoxic activity against MCF-7, PC-3, and Caco-2, compared with normal Vero cells. Further, its effects on cell cycle arrest, apoptosis induction and expression of apoptosis-related genes were assessed. The phytochemical screening revealed the presence of fatty acids and their esters in addition to phytosterols, steroid derivatives, and bioflavonoid glycosides with oleic and palmitic acids being the prevalent components (24.12 and 21.56%, respectively). The results showed considerable cytotoxic activity of the extract against the three cancer cell lines (MCF-7, PC-3, and Caco-2) with a selectivity index ranging from 5.07 to 6.52. This effect was further confirmed with the accompanied increased total apoptosis of treated PC-3 cells (19.22% of the total number of cells) compared to the control cells (0.64% of the total number of cells) with cell cycle arrest at G1 phase and the increased transcription of pro-apoptotic genes including (3.69) and (3.33) expressed as fold change (2^ ΔΔCT). The calculated minimum inhibitory concentration (MIC) was similar (62.5 µg/mL) against the three tested bacterial strains (, and ), while it was higher than 1000 µg/mL for the fungal species (, , and ). Our findings suggest a promising anticancer activity for , which paves the way for more detailed future studies.
PubMed: 36235487
DOI: 10.3390/plants11192621 -
Journal of Global Antimicrobial... Dec 2022A recent occurrence of carbapenemase-producing Acinetobacter ursingii was reported in the Netherlands and comprised three unrelated strains carrying the bla and bla...
OBJECTIVES
A recent occurrence of carbapenemase-producing Acinetobacter ursingii was reported in the Netherlands and comprised three unrelated strains carrying the bla and bla encoding genes. The objective was to investigate a putative common source of the carbapenemase resistance genes and plasmids in these A. ursingii strains.
METHODS
Hybrid assembly of short-read and long-read sequencing data was performed using Unicycler and assembled genomes were analysed by ResFinder and PlasmidFinder.
RESULTS
Hybrid assemblies of A. ursingii genomes yielded a circular chromosome, a large plasmid harboring bla and bla genes (sizes 259-317kb), and four to five other smaller plasmids. ResFinder analyses revealed 16 other acquired resistance genes on the plasmids carrying the bla and bla genes. These 18 genes encode resistance towards eight antibiotic classes. The smaller plasmids did not carry acquired resistance genes. Comparative analysis showed that the three bla/bla plasmids were similar (61%-83%) and shared 13 to 17 of the 18 resistance genes. BLAST analysis showed that the bla/bla plasmids were not reported before. However, a close match with a 399 kb plasmid from Acinetobacter johnsonii was found (99% similarity, 80% coverage). This A. johnsonii plasmid contains the bla gene, but lacks bla, and it shares eight other resistance genes with those present on the A. ursingii bla/bla plasmids.
CONCLUSION
Three bla/bla-carrying plasmids were characterized in three carbapenemase-producing A. ursingii strains. The plasmids were highly similar, suggesting a putative common source or co-selection of resistance genes from A. johnsonii. These results provide initial insights in the dissemination of carbapenem-resistance in A. ursingii in the Netherlands.
Topics: Microbial Sensitivity Tests; Netherlands; Plasmids; beta-Lactamases
PubMed: 36184039
DOI: 10.1016/j.jgar.2022.09.006 -
International Journal of Food... Nov 2022Salmonella enterica is one of the leading causes of foodborne gastroenteritis worldwide. In the food production environment, many bacterial species co-exist on surfaces...
Salmonella enterica is one of the leading causes of foodborne gastroenteritis worldwide. In the food production environment, many bacterial species co-exist on surfaces in biofilm structures, which can act as reservoirs of microbial contamination of food products. Polymicrobial biofilms have been shown to have greater tolerance to antimicrobials, such as disinfectants, however the mechanistic basis of this is poorly understood. In this study, S. enterica subsp. enterica serovar Liverpool was co-cultured in mixed-species biofilms with bacteria isolated from the food production environment and challenged with the cationic biocide disinfectant, benzalkonium chloride (BC). Co-culture with the common environmental bacterium Acinetobacter johnsonii resulted in >200-fold higher resistance of S. Liverpool to BC, compared to mono-culture biofilms. The transcriptional response of S. enterica to biofilm co-culture was determined using a dual RNA-seq strategy. Genes controlled by the PhoPQ and PmrAB two-component systems, involved in lipid A modification and associated with cationic antimicrobial peptide resistance (CAMP) of S. Liverpool, were significantly upregulated. Deletion of either the phoP or pmrA genes resulted in an increase in susceptibility to BC, suggesting that activation of their regulons during co-culture enhances BC resistance. S. Liverpool lipid A profiles changed significantly upon co-culturing, with greater incorporation of both phosphoethanolamine and palmitate, which was dependent upon activation of PhoPQ and PmrAB. We conclude that when grown in the presence of A. johnsonii, S. Liverpool increases its tolerance to cationic BC disinfection by remodelling its cell envelope including reducing the net negative charge of lipid A and increasing lipid A acyl density.
Topics: Acinetobacter; Benzalkonium Compounds; Biofilms; Coculture Techniques; Disinfectants; Lipid A; Palmitates; Salmonella enterica
PubMed: 36095868
DOI: 10.1016/j.ijfoodmicro.2022.109905