Cell-free supernatants produced by lactic acid bacteria reduce Salmonella population in vitro

Microbiology ◽  
2021 ◽  
Vol 167 (11) ◽  
Author(s):  
Alberto Gonçalves Evangelista ◽  
Jessica Audrey Feijó Corrêa ◽  
João Vitor Garcia dos Santos ◽  
Eduardo Henrique Custódio Matté ◽  
Mônica Moura Milek ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Lactic Acid ◽  
Antimicrobial Resistance ◽  
Lactic Acid Bacteria ◽  
Type Species ◽  
Feed Additives ◽  
Poultry Feed ◽  
Content Type ◽  
Link Type

The genus Salmonella is closely associated with foodborne outbreaks and animal diseases, and reports of antimicrobial resistance in Salmonella species are frequent. Several alternatives have been developed to control this pathogen, such as cell-free supernatants (CFS). Our objective here was to evaluate the use of lactic acid bacteria (LAB) CFS against Salmonella in vitro. Seventeen strains of LAB were used to produce CFS, and their antimicrobial activity was screened towards six strains of Salmonella . In addition, CFS were also pH-neutralized and/or boiled. Those with the best results were lyophilized. MICs of lyophilized CFS were 11.25–22.5 g l–1. Freeze-dried CFS were also used to supplement swine and poultry feed (11.25 g kg–1) and in vitro simulated digestion of both species was performed, with Salmonella contamination of 5×106 and 2×105 c.f.u. g−1 of swine and poultry feed, respectively. In the antimicrobial screening, all acidic CFS were able to inhibit the growth of Salmonella . After pH neutralization, Lactobacillus acidophilus Llorente, Limosilactobacillus fermentum CCT 1629, Lactiplantibacillus plantarum PUCPR44, Limosilactobacillus reuteri BioGaia, Lacticaseibacillus rhamnosus ATCC 7469 and Pediococcus pentosaceus UM116 CFS were the only strains that partially maintained their antimicrobial activity and, therefore, were chosen for lyophilization. In the simulated swine digestion, Salmonella counts were reduced ≥1.78 log c.f.u. g–1 in the digesta containing either of the CFS. In the chicken simulation, a significant reduction was obtained with all CFS used (average reduction of 0.59±0.01 log c.f.u. ml–1). In general, the lyophilized CFS of L. fermentum CCT 1629, L. rhamnosus ATCC 7469 and L. acidophilus Llorente presented better antimicrobial activity. In conclusion, CFS show potential as feed additives to control Salmonella in animal production and may be an alternative to the use of antibiotics, minimizing problems related to antimicrobial resistance.

scholarly journals Preterm infants harbour diverse Klebsiella populations, including atypical species that encode and produce an array of antimicrobial resistance- and virulence-associated factors

2020 ◽  
Vol 6 (6) ◽  
Author(s):  
Yuhao Chen ◽  
Thomas C. Brook ◽  
Cho Zin Soe ◽  
Ian O'Neill ◽  
Cristina Alcon-Giner ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Preterm Infants ◽  
Type Species ◽  
Metagenomic Data ◽  
Preterm Neonates ◽  
Content Type ◽  
Link Type ◽  
Faecal Samples ◽  
Antimicrobial Resistance Genes

Klebsiella spp. are frequently enriched in the gut microbiota of preterm neonates, and overgrowth is associated with necrotizing enterocolitis (NEC), nosocomial infections and late-onset sepsis. Little is known about the genomic and phenotypic characteristics of preterm-associated Klebsiella , as previous studies have focused on the recovery of antimicrobial-resistant isolates or culture-independent molecular analyses. The aim of this study was to better characterize preterm-associated Klebsiella populations using phenotypic and genotypic approaches. Faecal samples from a UK cohort of healthy and sick preterm neonates (n=109) were screened on MacConkey agar to isolate lactose-positive Enterobacteriaceae . Whole-genome sequences were generated for Klebsiella spp., and virulence and antimicrobial resistance genes identified. Antibiotic susceptibility profiling and in vitro macrophage and iron assays were undertaken for the Klebsiella strains. Metapangenome analyses with a manually curated genome dataset were undertaken to examine the diversity of Klebsiella oxytoca and related bacteria in a publicly available shotgun metagenome dataset. Approximately one-tenth of faecal samples harboured Klebsiella spp. ( Klebsiella pneumoniae , 7.3 %; Klebsiella quasipneumoniae , 0.9 %; Klebsiella grimontii , 2.8 %; Klebsiella michiganensis , 1.8 %). Isolates recovered from NEC- and sepsis-affected infants and those showing no signs of clinical infection (i.e. ‘healthy’) encoded multiple β-lactamases. No difference was observed between isolates recovered from healthy and sick infants with respect to in vitro siderophore production (all encoded enterobactin in their genomes). All K. pneumoniae , K. quasipneumoniae , K. grimontii and K. michiganensis faecal isolates tested were able to reside and persist in macrophages, indicating their immune evasion abilities. Metapangenome analyses of published metagenomic data confirmed our findings regarding the presence of K. michiganensis in the preterm gut. There is little difference in the phenotypic and genomic characteristics of Klebsiella isolates recovered from healthy and sick infants. Identification of β-lactamases in all isolates may prove problematic when defining treatment regimens for NEC or sepsis, and suggests that healthy preterm infants contribute to the resistome. Refined analyses with curated sequence databases are required when studying closely related species present in metagenomic data.

scholarly journals Sporolactobacillus shoreae sp. nov. and Sporolactobacillus spathodeae sp. nov., two spore-forming lactic acid bacteria isolated from tree barks in Thailand

2015 ◽  
Vol 65 (Pt_4) ◽  
pp. 1220-1226 ◽  
Author(s):  
Tanatip Thamacharoensuk ◽  
Maki Kitahara ◽  
Moriya Ohkuma ◽  
Nuttha Thongchul ◽  
Somboon Tanasupawat
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
16S Rrna ◽  
Type Species ◽  
Gene Sequence ◽  
Rrna Gene ◽  
Rrna Gene Sequence ◽  
Content Type ◽  
Link Type ◽  
Tree Barks

Two Gram-stain-positive, endospore-forming lactic acid bacteria, designated BK92T and BK117-1T, were isolated from tree barks in Thailand. Cells were catalase-negative and facultatively anaerobic rods. 16S rRNA gene sequence analysis indicated that these strains belonged to the genus Sporolactobacillus . Strains BK92T and BK117-1T showed the highest 16S rRNA gene sequence similarity to Sporolactobacillus putidus QC81-06T with 97.7 % and 97.1 % similarity, respectively. Analysis of phylogenetic relationships based on 16S rRNA and gyrB gene sequencing revealed that the positions of strains BK92T and BK117-1T were clearly separated from all related species of the genus Sporolactobacillus . Strains BK92T and BK117-1T had low DNA–DNA relatedness between each other and also with S. putidus QC81-06T and Sporolactobacillus vineae SL153T. The DNA G+C content of strains BK92T and BK117-1T was 46.6 mol% and 47.4 mol%, respectively. The major fatty acids of strains BK92T and BK117-1T were anteiso-C17 : 0 and anteiso-C15 : 0. They contained meso-diaminopimelic acid in cell-wall peptidoglycan and had menaquinone with seven isoprene units (MK-7) as the predominant menaquinone. Based on evidence including phenotypic, genotypic and chemotaxonomic studies, strains BK92T and BK117-1T should be classified as representatives of novel species of the genus Sporolactobacillus , for which the names Sporolactobacillus shoreae sp. nov. and Sporolactobacillus spathodeae sp. nov. are proposed, respectively. The type strains are BK92T ( = JCM 19541T = LMG 28365T = PCU 336T = TISTR 2234T) and BK117-1T ( = JCM 19542T = LMG 28366T = PCU 337T = TISTR 2235T).

scholarly journals Lactobacillus furfuricola sp. nov., isolated from Nukadoko, rice bran paste for Japanese pickles

2014 ◽  
Vol 64 (Pt_8) ◽  
pp. 2902-2906 ◽  
Author(s):  
Tomohiro Irisawa ◽  
Naoto Tanaka ◽  
Maki Kitahara ◽  
Mitsuo Sakamoto ◽  
Moriya Ohkuma ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Gene Sequence ◽  
Rrna Gene ◽  
Rrna Gene Sequence ◽  
Content Type ◽  
Link Type

Two strains of lactic acid bacteria, Nu27T and Nu29, were isolated from Nukadoko, rice bran paste for Japanese pickles. The isolates were Gram-stain-positive, rod-shaped, catalase-negative, non-motile and facultatively anaerobic lactic acid bacteria. The isolates showed identical 16S rRNA gene sequences. The closest relatives to strain Nu27T based on 16S rRNA gene sequence similarities were Lactobacillus versmoldensis KU-3T (98.9 % 16S rRNA gene sequence similarity), Lactobacillus nodensis iz4bT (96.3 %) and Lactobacillus tucceti CECT 5290T (97.2 %). DNA–DNA relatedness values revealed genotype separation of the two isolates from the above three species. Based on the physiological, biochemical and genotypic characteristics provided, the isolates represent a novel species of the genus Lactobacillus , for which name is Lactobacillus furfuricola proposed. The type strain is Nu 27T ( = JCM 18764T = NRIC 0900T = DSM 27174T).

Impact of pH on growth of Staphylococcus epidermidis and Staphylococcus aureus in vitro

2021 ◽  
Vol 70 (9) ◽  
Author(s):  
Vidula Iyer ◽  
Janhavi Raut ◽  
Anindya Dasgupta
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Kinetics ◽  
Staphylococcus Epidermidis ◽  
Type Species ◽  
Ph Dependence ◽  
Skin Microbiome ◽  
Content Type ◽  
Link Type ◽  
Kinetics Of

The pH of skin is critical for skin health and resilience and plays a key role in controlling the skin microbiome. It has been well reported that under dysbiotic conditions such as atopic dermatitis (AD), eczema, etc. there are significant aberrations of skin pH, along with a higher level of Staphylococcus aureus compared to the commensal Staphylococcus epidermidis on skin. To understand the effect of pH on the relative growth of S. epidermidis and S. aureus , we carried out simple in vitro growth kinetic studies of the individual microbes under varying pH conditions. We demonstrated that the growth kinetics of S. epidermidis is relatively insensitive to pH within the range of 5–7, while S. aureus shows a stronger pH dependence in that range. Gompertz’s model was used to fit the pH dependence of the growth kinetics of the two bacteria and showed that the equilibrium bacterial count of S. aureus was the more sensitive parameter. The switch in growth rate happens at a pH of 6.5–7. Our studies are in line with the general hypothesis that keeping the skin pH within an acidic range is advantageous in terms of keeping the skin microbiome in balance and maintaining healthy skin.

Carnobacterium iners sp. nov., a psychrophilic, lactic acid-producing bacterium from the littoral zone of an Antarctic pond

2013 ◽  
Vol 63 (Pt_4) ◽  
pp. 1370-1375 ◽  
Author(s):  
Isabel Snauwaert ◽  
Bart Hoste ◽  
Katrien De Bruyne ◽  
Karolien Peeters ◽  
Luc De Vuyst ◽  
...  
Keyword(s):  
Lactic Acid ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Littoral Zone ◽  
Type Species ◽  
Novel Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type

Two lactic acid-producing, Gram-stain-positive rods were isolated from a microbial mat actively growing in the littoral zone of an Antarctic lake (Forlidas Pond) in the Pensacola mountains and studied using a polyphasic taxonomic approach. The isolates were examined by phylogenetic analysis of the 16S rRNA gene, multilocus sequence analysis of pheS, rpoA and atpA, and biochemical and genotypic characteristics. One strain, designated LMG 26641, belonged to Carnobacterium alterfunditum and the other strain, designated LMG 26642T, could be assigned to a novel species, with Carnobacterium funditum DSM 5970T as its closest phylogenetic neighbour (99.2 % 16S rRNA gene sequence similarity). Carnobacterium iners sp. nov. could be distinguished biochemically from other members of the genus Carnobacterium by the lack of acid production from carbohydrates. DNA–DNA relatedness confirmed that strain LMG 26642T represented a novel species, for which we propose the name Carnobacterium iners sp. nov. (type strain is LMG 26642T  = CCUG 62000T).

scholarly journals In vitro synergy of 5-nitrofurans, vancomycin and sodium deoxycholate against Gram-negative pathogens

2021 ◽  
Author(s):  
Catrina Olivera ◽  
Vuong Van Hung Le ◽  
Catherine Davenport ◽  
Jasna Rakonjac
Keyword(s):  
Growth Inhibition ◽  
Type Species ◽  
Sodium Deoxycholate ◽  
Gram Positive ◽  
Bacterial Killing ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Time Kill

Introduction. There is an urgent need for effective therapies against bacterial infections, especially those caused by antibiotic-resistant Gram-negative pathogens. Hypothesis. Synergistic combinations of existing antimicrobials show promise due to their enhanced efficacies and reduced dosages which can mitigate adverse effects, and therefore can be used as potential antibacterial therapy. Aim. In this study, we sought to characterize the in vitro interaction of 5-nitrofurans, vancomycin and sodium deoxycholate (NVD) against pathogenic bacteria. Methodology. The synergy of the NVD combination was investigated in terms of growth inhibition and bacterial killing using checkerboard and time-kill assays, respectively. Results. Using a three-dimensional checkerboard assay, we showed that 5-nitrofurans, sodium deoxycholate and vancomycin interact synergistically in the growth inhibition of 15 out of 20 Gram-negative strains tested, including clinically significant pathogens such as carbapenemase-producing Escherichia coli , Klebsiella pneumoniae and Acinetobacter baumannii , and interact indifferently against the Gram-positive strains tested. The time-kill assay further confirmed that the triple combination was bactericidal in a synergistic manner. Conclusion. This study demonstrates the synergistic effect of 5-nitrofurans, sodium deoxycholate and vancomycin against Gram-negative pathogens and highlights the potential of the combination as a treatment for Gram-negative and Gram-positive infections.

scholarly journals Genetic regulation, biochemical properties and physiological importance of arginase from Sinorhizobium meliloti

Microbiology ◽  
2020 ◽  
Vol 166 (5) ◽  
pp. 484-497 ◽  
Author(s):  
Alejandra Arteaga Ide ◽  
Victor M. Hernández ◽  
Liliana Medina-Aparicio ◽  
Edson Carcamo-Noriega ◽  
Lourdes Girard ◽  
...  
Keyword(s):  
Type Species ◽  
Sinorhizobium Meliloti ◽  
Arginase Activity ◽  
Wild Type ◽  
Mobility Shift ◽  
Content Type ◽  
Link Type ◽  
Arginine Catabolism

In bacteria, l-arginine is a precursor of various metabolites and can serve as a source of carbon and/or nitrogen. Arginine catabolism by arginase, which hydrolyzes arginine to l-ornithine and urea, is common in nature but has not been studied in symbiotic nitrogen-fixing rhizobia. The genome of the alfalfa microsymbiont Sinorhizobium meliloti 1021 has two genes annotated as arginases, argI1 (smc03091) and argI2 (sma1711). Biochemical assays with purified ArgI1 and ArgI2 (as 6His-Sumo-tagged proteins) showed that only ArgI1 had detectable arginase activity. A 1021 argI1 null mutant lacked arginase activity and grew at a drastically reduced rate with arginine as sole nitrogen source. Wild-type growth and arginase activity were restored in the argI1 mutant genetically complemented with a genomically integrated argI1 gene. In the wild-type, arginase activity and argI1 transcription were induced several fold by exogenous arginine. ArgI1 purified as a 6His-Sumo-tagged protein had its highest in vitro enzymatic activity at pH 7.5 with Ni2+ as cofactor. The enzyme was also active with Mn2+ and Co2+, both of which gave the enzyme the highest activities at a more alkaline pH. The 6His-Sumo-ArgI1 comprised three identical subunits based on the migration of the urea-dissociated protein in a native polyacrylamide gel. A Lrp-like regulator (smc03092) divergently transcribed from argI1 was required for arginase induction by arginine or ornithine. This regulator was designated ArgIR. Electrophoretic mobility shift assays showed that purified ArgIR bound to the argI1 promoter in a region preceding the predicted argI1 transcriptional start. Our results indicate that ArgI1 is the sole arginase in S. meliloti , that it contributes substantially to arginine catabolism in vivo and that argI1 induction by arginine is dependent on ArgIR.

scholarly journals Comparative genomics of Staphylococcus epidermidis from prosthetic-joint infections and nares highlights genetic traits associated with antimicrobial resistance, not virulence

2021 ◽  
Author(s):  
Emeli Månsson ◽  
Thor Bech Johannesen ◽  
Åsa Nilsdotter-Augustinsson ◽  
Bo Söderquist ◽  
Marc Stegger
Keyword(s):  
Population Structure ◽  
Antimicrobial Resistance ◽  
Staphylococcus Epidermidis ◽  
Type Species ◽  
Genetic Traits ◽  
Content Type ◽  
Link Type ◽  
Joint Infections ◽  
Prosthetic Joint ◽  
Prosthetic Joint Infections

There is increased awareness of the worldwide spread of specific epidemic multidrug-resistant (MDR) lineages of the human commensal Staphylococcus epidermidis . Here, using bioinformatic analyses accounting for population structure, we determined genomic traits (genes, SNPs and k-mers) that distinguish S. epidermidis causing prosthetic-joint infections (PJIs) from commensal isolates from nares, by analysing whole-genome sequencing data from S. epidermidis from PJIs prospectively collected over 10 years in Sweden, and contemporary S. epidermidis from the nares of patients scheduled for arthroplasty surgery. Previously suggested virulence determinants and the presence of genes and mutations linked to antimicrobial resistance (AMR) were also investigated. Publicly available S. epidermidis sequences were used for international extrapolation and validation of findings. Our data show that S. epidermidis causing PJIs differed from nasal isolates not by virulence but by traits associated with resistance to compounds used in prevention of PJIs: β-lactams, aminoglycosides and chlorhexidine. Almost a quarter of the PJI isolates did not belong to any of the previously described major nosocomial lineages, but the AMR-related traits were also over-represented in these isolates, as well as in international S. epidermidis isolates originating from PJIs. Genes previously associated with virulence in S. epidermidis were over-represented in individual lineages, but failed to reach statistical significance when adjusted for population structure. Our findings suggest that the current strategies for prevention of PJIs select for nosocomial MDR S. epidermidis lineages that have arisen from horizontal gene transfer of AMR-related traits into multiple genetic backgrounds.

Emergence of mgrB locus deletion mediating polymyxin resistance in pandemic KPC-producing Klebsiella pneumoniae ST15 lineage

2021 ◽  
Author(s):  
Luís Guilherme de Araújo Longo ◽  
Herrison Fontana ◽  
Viviane Santos de Sousa ◽  
Natalia Chilinque Zambão da Silva ◽  
Ianick Souto Martins ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Klebsiella Pneumoniae ◽  
Type Species ◽  
Virulence Genes ◽  
Health Concern ◽  
Beta Lactamase ◽  
Content Type ◽  
Link Type ◽  
Antimicrobial Resistance Genes ◽  
Encoding Gene

Klebsiella pneumoniae causes a diversity of infections in both healthcare and community settings. This pathogen is showing an increased ability to accumulate antimicrobial resistance and virulence genes, making it a public health concern. Here we describe the whole-genome sequence characteristics of an ST15 colistin-resistant K. pneumoniae isolate obtained from a blood culture of a 79-year-old female patient admitted to a university hospital in Brazil. Kp14U04 was resistant to most clinically useful antimicrobial agents, remaining susceptible only to aminoglycosides and fosfomycin. The colistin resistance in this isolate was due to a ~1.3 kb deletion containing four genes, namely mgrB, yebO, yobH and the transcriptional regulator kdgR. The study isolate presented a variety of antimicrobial resistance genes, including the carbapenemase-encoding gene bla KPC-2, the extended-spectrum beta-lactamase (ESBL)-encoding gene bla SHV-28 and the beta-lactamase-encoding gene bla OXA-1. Additionally, Kp14U04 harboured a multiple stress resistance protein, efflux systems and regulators, heavy metal resistance and virulence genes, plasmids, prophage-related sequences and genomic islands. These features revealed the high potential of this isolate to resist antimicrobial therapy, survive in adverse environments, cause infections and overcome host defence mechanisms.

Companilactobacillus pabuli sp. nov., a lactic acid bacterium isolated from animal feed

2021 ◽  
Author(s):  
Ji Young Jung ◽  
Hye Kyeong Kang ◽  
Hyun Mi Jin ◽  
Sang-Soo Han ◽  
Young Chul Kwon ◽  
...  
Keyword(s):  
Lactic Acid ◽  
16S Rrna ◽  
Dna Hybridization ◽  
Type Species ◽  
Novel Species ◽  
Rrna Gene ◽  
Average Nucleotide Identity ◽  
Content Type ◽  
Link Type ◽  
The 16S Rrna Gene

A Gram-positive, facultative anaerobic, catalase-negative, non-motile, non-spore-forming and rod-shaped lactic acid bacterium strain, denoted as NFFJ11T and isolated from total mixed fermentation feed in the Republic of Korea, was characterized through polyphasic approaches, including sequence analyses of the 16S rRNA gene and housekeeping genes (rpoA and pheS), determination of average nucleotide identity and in silico DNA–DNA hybridization, fatty acid methyl ester analysis, and phenotypic characterization. Phylogenetic analyses based on 16S rRNA, rpoA and pheS gene sequences revealed that strain NFFJ11T belonged to the genus Companilactobacillus . The 16S rRNA gene sequence of strain NFFJ11T exhibited high similarity to Companilactobacillus formosensis S215T (99.66 %), Companilactobacillus farciminis Rv4 naT (99.53 %), Companilactobacillus crustorum LMG 23699T (99.19 %), Companilactobacillus futsaii YM 0097T (99.06 %), Companilactobacillus zhachilii HBUAS52074T (98.86 %) and Companilactobacillus heilongiiangensis S4-3T (98.66 %). However, average nucleotide identity and in silico DNA–DNA hybridization values for these type strains were in the range of 79.90–92.93 % and 23.80–49.30 %, respectively, which offer evidence that strain NFFJ11T belongs to a novel species of the genus Companilactobacillus . The cell-wall peptidoglycan type was A4α (l-Lys–d-Asp) and the G+C content of the genomic DNA was 35.7 mol%. The main fatty acids of strain NFFJ11T were C18 : 1  ω9c (43.3 %), C16 : 0 (20.1 %) and summed feature 7 (18.3 %; comprising any combination of C19 : 1  ω7c, C19 : 1  ω6c and C19 : 0 cyclo ω10c). Through polyphasic taxonomic analysis, it was observed that strain NFFJ11T represents a novel species belonging to the genus Companilactobacillus , for which the name Companilactobacillus pabuli sp. nov. is proposed. The type strain is NFFJ11T (= KACC 21771T= JCM 34088T).

Sign in / Sign up

Export Citation Format

Share Document