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Microorganisms Mar 2020Persistent use of the insecticide D-cyphenothrin has resulted in heavy environmental contamination and public concern. However, microbial degradation of D-cyphenothrin...
Persistent use of the insecticide D-cyphenothrin has resulted in heavy environmental contamination and public concern. However, microbial degradation of D-cyphenothrin has never been investigated and the mechanism remains unknown. During this study, for the first time, an efficient D-cyphenothrin-degrading bacterial strain HLJ-10 was identified. Response surface methodology was successfully employed by using Box-Behnken design to optimize the culture conditions. At optimized conditions, over 90% degradation of D-cyphenothrin (50 mg·L) was achieved in a mineral salt medium within 7 d. Kinetics analysis revealed that its half-life was reduced by 61.2 d, in comparison with the uninoculated control. Eight intermediate metabolites were detected in the biodegradation pathway of D-cyphenothrin including -D-cyphenothrin, -D-cyphenothrin, 3-phenoxybenzaldehyde, α-hydroxy-3-phenoxy-benzeneacetonitrile, -2,2-dimethyl-3-propenyl-cyclopropanol, 2,2-dimethyl-3-propenyl-cyclopropionic acid, -2,2-dimethyl-3-propenyl-cyclopropionaldehyde, and 1,2-benzenedicarboxylic acid, dipropyl ester. This is the first report about the degradation of D-cyphenothrin through cleavage of carboxylester linkage and diaryl bond. In addition to degradation of D-cyphenothrin, strain HLJ-10 effectively degraded a wide range of synthetic pyrethroids including permethrin, tetramethrin, bifenthrin, allethrin, and chlorempenthrin, which are also widely used insecticides with environmental contamination problems. Bioaugmentation of D-cyphenothrin-contaminated soils with strain HLJ-10 substantially enhanced its degradation and over 72% of D-phenothrin was removed from soils within 40 d. These findings unveil the biochemical basis of a highly efficient D-cyphenothrin-degrading bacterial isolate and provide potent agents for eliminating environmental residues of pyrethroids.
PubMed: 32225056
DOI: 10.3390/microorganisms8040473 -
BMC Evolutionary Biology Jan 2020The theory of trade-off suggests that limited resources should lead to trade-off in resource intensive traits such as, immunity related and sexually selected traits in...
BACKGROUND
The theory of trade-off suggests that limited resources should lead to trade-off in resource intensive traits such as, immunity related and sexually selected traits in males. Alternatively, sexual exaggerations can also act as an honest indicator of underlying immunocompetence, leading to positive correlations between these traits. Evidences in support of either hypothesis in invertebrates are equivocal. Whereas several studies have addressed this question, few have used naturally occurring pathogens and realized post infection realized immunity (e.g., survivorship) to assay the fitness correlations between these two sets of traits.
RESULTS
Adopting an experimental evolution approach, we evolved replicate populations of Drosophila melanogaster under high and low sexual selection regimes for over a hundred generations and found the following in virgin and mated males in three separate assays: a.Post infection survivorship against two natural pathogens - Pseudomonas entomophila (Pe) and Staphylococcus succinus (Ss): Mated males survived better against Pe, but were no different than virgins against Ss.b.Bacterial clearance ability against a third natural pathogen Providencia rettgeri (Pr): Mated males had significantly lower CFUs than virgins. However, sexual selection history had no effect on realized immunity of either virgin or mated males.
CONCLUSION
We show that while mating can affect realized immunity in a pathogen specific way, sexual selection did not affect the same. The results highlight that complex polygenic traits such as immunity and reproductive traits not necessarily evolve following a binary trade-off model. We also stress the importance natural pathogens while studying sexual selection-immunity correlations.
Topics: Animals; Biological Evolution; Colony Count, Microbial; Drosophila melanogaster; Female; Immunity; Male; Phenotype; Proportional Hazards Models; Pseudomonas; Reproduction; Selection, Genetic; Sexual Behavior, Animal; Staphylococcus
PubMed: 31992187
DOI: 10.1186/s12862-019-1574-1 -
Applied and Environmental Microbiology Feb 2020This study aimed at establishing the effects of attenuated starters and surface bacteria on various features of caciotta cheese. The cheese undergoes a ripening period...
This study aimed at establishing the effects of attenuated starters and surface bacteria on various features of caciotta cheese. The cheese undergoes a ripening period during which the house microbiota contaminates the surface. Conventional cheese (the control cheese [CC]) is made using only primary starters. Primary starters and attenuated (i.e., unable to grow and synthesize lactic acid) () subsp. were used to produce caciotta cheese without (ATT cheese) or with an inoculum of surface bacteria: (i) () (LL cheese), (ii) (VC cheese), (iii) (SE cheese), (iv) (BX cheese), and (v) a mixture of all four (MIX cheese). Attenuated increased microbial diversity during cheese ripening. At the core, attenuated starter mainly increased indigenous lactococci and group bacteria. At the surface, the main effect was on Autochthonous strains took advantage of the attenuated starter, becoming dominant. Adjunct positively affected group bacteria on the LL cheese surface. Adjunct , , and did not become dominant. Surfaces of VC, SE, and BX cheeses mainly harbored Peptidase activities were higher in cheeses made with attenuated starter than in CC, which had the lowest concentration of free amino acids. Based on the enzymatic activities of adjunct , LL and MIX cheeses exhibited the highest glutamate dehydrogenase, cystathionine-γ-lyase, and esterase activities. As shown by multivariate statistical analyses, LL and MIX cheeses showed the highest similarity for microbiological and biochemical features. LL and MIX cheeses received the highest scores for overall sensory acceptability. This study provides in-depth knowledge of the effects of attenuated starters and surface bacterial strains on the microbiota and related metabolic activities during cheese ripening. The use of attenuated strongly impacted the microbiota assembly of caciotta cheese. This led to improved biochemical and sensory features compared to conventional cheese. Among surface bacterial strains, played a key role in the metabolic activities involved in cheese ripening. This resulted in an improvement of the sensory quality of caciotta cheese. The use of attenuated lactic acid bacteria and the surface adjunct could be a useful biotechnology to improve the flavor formation of caciotta cheese.
Topics: Cheese; Food Microbiology; Lactococcus lactis; Microbiota; Taste
PubMed: 31862717
DOI: 10.1128/AEM.02165-19 -
Journal of Microbiology and... Mar 2020To shed light on the genetic differences among food-originated coagulase-negative (CNS), we performed pan-genome analysis of five species: (two strains), (two...
To shed light on the genetic differences among food-originated coagulase-negative (CNS), we performed pan-genome analysis of five species: (two strains), (two strains), (three strains), (two strains), and (one strain). The pan-genome size increases with each new strain and currently holds about 4,500 genes from 10 genomes. Specific genes were shown to be strain dependent but not species dependent. Most specific genes were of unknown function or encoded restriction-modification enzymes, transposases, or prophages. Our results indicate that unique genes have been acquired or lost by convergent evolution within individual strains.
Topics: Food Microbiology; Genome, Bacterial; Genomics; Phylogeny; Plasmids; Staphylococcus; Transposases
PubMed: 31847510
DOI: 10.4014/jmb.1910.10049 -
Journal of Dairy Science Oct 2019Brining is an important step in cheese making, and using brine baths for this purpose is common practice in German dairies. Time of brining, brine concentration, and...
Brining is an important step in cheese making, and using brine baths for this purpose is common practice in German dairies. Time of brining, brine concentration, and composition of the complex and heterogeneous microbiota, including coagulase-negative staphylococci (CNS), contribute to the ripening and taste of cheese. As well as producing staphylococcal enterotoxins, some CNS show antibiotic resistance; therefore, we isolated 52 strains of presumptive CNS from cheese brines from 13 factories in Germany. Species identification by sodA gene sequencing revealed that 50 isolates were CNS: 31 Staphylococcus saprophyticus, 4 Staphylococcus carnosus, 4 Staphylococcus equorum, 3 Staphylococcus sciuri, 2 Staphylococcus hominis, and 2 Staphylococcus warneri. One isolate each was identified as Staphylococcus epidermidis, Staphylococcus pasteurii, Staphylococcus succinus, and Staphylococcus xylosus. Further subtyping of the Staph. saprophyticus isolates to the subspecies level revealed the presence of 6 Staph. saprophyticus ssp. saprophyticus. Using pulsed-field gel electrophoresis with the identified Staph. saprophyticus strains, 12 independent clones were identified, resulting in the exclusion of 18 strains from further testing. In 19 of the remaining 32 CNS isolates, resistance to antibiotics was observed. Resistance was found against oxacillin (17), penicillin (5), and cefoxitin (1). Four isolates expressed resistance to both oxacillin and penicillin. No resistance was found to enrofloxacin, tetracycline, gentamicin, or erythromycin. Then, PCR analysis for antibiotic resistance genes was performed for 22 different genes. Only genes blaZ and bla were found in 7 isolates. These isolates were selected for challenge tests with different concentrations of lactic acid and NaCl to examine whether expression of antibiotic resistance was influenced by these stressors. An increase in the minimal inhibitory concentration from 0 to 2.0 µg/mL was seen for trimethoprim/sulfamethoxazole only in one isolate of Staph. saprophyticus at an increased lactic acid concentration. Finally, all isolates were tested for genetic determinants (entA, entB, entC, entD, and entE) of the most common staphylococcal enterotoxins; none of these genes were detected. We found no indication for unacceptable risks originating from the isolated CNS.
Topics: Animals; Anti-Bacterial Agents; Cefoxitin; Cheese; Coagulase; Drug Resistance, Bacterial; Electrophoresis, Gel, Pulsed-Field; Enterotoxins; Food Handling; Germany; Microbial Sensitivity Tests; Oxacillin; Penicillin G; Salts; Staphylococcus; Staphylococcus epidermidis
PubMed: 31421877
DOI: 10.3168/jds.2018-15610