| 1. |
- Alreshidi, M. M., et al.
(författare)
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Amino acids and proteomic acclimation of Staphylococcus aureus when incubated in a defined minimal medium supplemented with 5% sodium chloride
- 2019
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Ingår i: Microbiologyopen. - : Wiley. - 2045-8827. ; 8:6
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is a versatile bacterium that can adapt to survive and grow in a wide range of salt concentrations. This study investigated whether the cells could mount a response to survive a challenge of 5% NaCl in a minimal incubation medium that would not support cell replication. Cells were grown in liquid culture, washed and then incubated for 90 min at 37 degrees C in a medium that contained only glycine and glucose as substrates in PBS plus trace elements. The control cells were compared with a treatment group which was incubated with an additional 5% NaCl. Significantly more glycine was taken up by the cells exposed to 5% NaCl compared with control cells, and both groups consumed 99% of the glucose supplied. The NaCl treated cells had significantly higher cytoplasmic levels of proline and glutamic acid as well as lower levels of alanine and methionine compared with the controls (p < 0.05). The levels of the two major cytoplasmic amino acids, aspartic acid and glycine, remained constant in control and treated cells. Proteomic analyses revealed that 10 proteins showed differential responses between the control and treatment groups. The reductions in proteins were primarily associated with processes of protein biosynthesis, pathogenicity, and cell adhesion. Since cell numbers remained constant during the incubation period in minimal medium, it was concluded that there was no cell division to support population growth. The results provided evidence that the cells in the minimal medium exposed to the NaCl treatment underwent in situ homeostatic changes to adjust to the new environmental conditions. It was proposed that this represented a phenotypic shift to form cells akin to small colony variants, with lower metabolic rates and lower levels of key proteins associated with pathogenicity.
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| 2. |
- Apine, E., et al.
(författare)
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Comparative analysis of the intestinal bacterial communities in mud crab Scylla serrata in South India
- 2021
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Ingår i: Microbiologyopen. - : Wiley. - 2045-8827. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the functions of the crustacean gut microbiome, but environmental parameters and habitat are known to affect the composition of the intestinal microbiome, which may in turn affect the physiological status of the host. The mud crab Scylla serrata is an economically important species, and is wild-caught, and farmed across the Indo-Pacific region. In this study, we compared the composition of the gut microbiome (in terms of gut microbial species richness and abundance) of S. serrata collected from wild sites, and farms, from the east and west coast of India, and also tested the effects of the environment on the composition. The water temperature had a statistically significant effect on gut microbiome composition, with microbial biodiversity decreasing with increasing water temperature. This could have negative effects on both wild and farmed mud crabs under future climate change conditions, although further research into the effects of temperature on gut microbiomes is required. By comparison, salinity, crab mass and carapace width, geographical location as well as whether they were farmed or wild-caught crabs did not have a significant impact on gut microbiome composition. The results indicate that farming does not significantly alter the composition of the gut microbiome when compared to wild-caught crabs.
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| 3. |
- Baltar, Federico, et al.
(författare)
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Prokaryotic community structure and respiration during long-term incubations
- 2012
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Ingår i: MicrobiologyOpen. - : Wiley. - 2045-8827. ; 1:2, s. 214-224
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of incubation assays for studies inmicrobial ecology that frequentlyrequire long confinement times, few reports are available in which changesin the assemblage structure of aquatic prokaryotes were monitored during longtermincubations.We measured rates of dissolved organic carbon degradation andmicrobial respiration by consumption of dissolved oxygen (DO) in four experimentswith Lake Kinneret near-surface water and, concomitantly, we analyzed thevariability in prokaryotic community structure during long-term dark bottle incubations.During the first 24 h, therewere only minor changes in bacterial communitycomposition. Thereafter there were marked changes in the prokaryotic communitystructure during the incubations. In contrast, oxygen consumption rates (a proxyfor both respiration and dissolved organic carbon degradation rates) remained stablefor up to 10–23 days. This study is one of the first to examine closely the phylogeneticchanges that occur in the microbial community of untreated freshwaterduring long-term (days) incubations in dark, sealed containers. Novel informationon the diversity of the main bacterial phylotypes that may be involved in dissolvedorganic matter degradation in lake Kinneret is also provided. Our results suggestthat, under certain ecological settings, constant community metabolic rates can bemaintained as a result of shifts in community composition.
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| 4. |
- Bengtsson, Torbjörn, 1955-, et al.
(författare)
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The lantibiotic gallidermin acts bactericidal against Staphylococcus epidermidis and Staphylococcus aureus and antagonizes the bacteria-induced proinflammatory responses in dermal fibroblasts
- 2018
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Ingår i: MicrobiologyOpen. - : John Wiley & Sons. - 2045-8827. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial resistance needs to be tackled from new angles, and antimicrobial peptides could be future candidates for combating bacterial infections. This study aims to investigate in vitro the bactericidal effects of the lantibiotic gallidermin on Staphylococcus epidermidis and Staphylococcus aureus, possible cytotoxic effects and its impact on host-microbe interactions. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of gallidermin were determined, and cytotoxicity and proinflammatory effects of gallidermin on fibroblasts, red blood cells (RBCs) and in whole blood were investigated. Both MIC and MBC for all four tested strains of S. epidermidis was 6.25 μg/ml. Both MIC and MBC for methicillin-sensitive S. aureus was 12.5 μg/ml and for methicillin-resistant S. aureus (MRSA) 1.56 μg/ml. Gallidermin displayed no cytotoxic effects on fibroblasts, only a high dose of gallidermin induced low levels of CXCL8 and interleukin-6. Gallidermin hemolyzed less than 1% of human RBCs, and did not induce reactive oxygen species production or cell aggregation in whole blood. In cell culture, gallidermin inhibited the cytotoxic effects of the bacteria and totally suppressed the bacteria-induced release of CXCL8 and interleukin-6 from fibroblasts. We demonstrate that gallidermin, expressing low cell cytotoxicity, is a promising candidate for treating bacterial infections caused by S. epidermidis and S. aureus, especially MRSA.
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| 5. |
- Brindefalk, B., et al.
(författare)
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Bacterial composition in Swedish raw drinking water reveals three major interacting ubiquitous metacommunities
- 2022
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Ingår i: Microbiologyopen. - : Wiley. - 2045-8827. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Background Surface raw water used as a source for drinking water production is a critical resource, sensitive to contamination. We conducted a study on Swedish raw water sources, aiming to identify mutually co-occurring metacommunities of bacteria, and environmental factors driving such patterns. Methods The water sources were different regarding nutrient composition, water quality, and climate characteristics, and displayed various degrees of anthropogenic impact. Water inlet samples were collected at six drinking water treatment plants over 3 years, totaling 230 samples. The bacterial communities of DNA sequenced samples (n = 175), obtained by 16S metabarcoding, were analyzed using a joint model for taxa abundance. Results Two major groups of well-defined metacommunities of microorganisms were identified, in addition to a third, less distinct, and taxonomically more diverse group. These three metacommunities showed various associations to the measured environmental data. Predictions for the well-defined metacommunities revealed differing sets of favored metabolic pathways and life strategies. In one community, taxa with methanogenic metabolism were common, while a second community was dominated by taxa with carbohydrate and lipid-focused metabolism. Conclusion The identification of ubiquitous persistent co-occurring bacterial metacommunities in freshwater habitats could potentially facilitate microbial source tracking analysis of contamination issues in freshwater sources.
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| 6. |
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| 7. |
- Ghosh, Devanita, 1990-, et al.
(författare)
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Coping with arsenic stress : Adaptations of arsenite-oxidizing bacterial membrane lipids to increasing arsenic levels
- 2018
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Ingår i: MicrobiologyOpen. - : John Wiley & Sons. - 2045-8827. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Elevated levels of arsenic (As) in aquifers of South East Asia have caused diverse health problems affecting millions of people who drink As-rich groundwater and consume various contaminated agriculture products. The biogeochemical cycling and mobilization/immobilization of As from its mineral-bound phase is controlled by pH, oxic/anoxic conditions, and different microbial processes. The increased As flux generated from ongoing biogeochemical processes in the subsurface in turn affects the in situ microbial communities. This study analyzes how the indigenous arsenite-oxidizing bacteria combat As stress by various biophysical alterations and self-adaptation mechanisms. Fifteen arsenite-oxidizing bacterial strains were isolated and identified using a polyphasic approach. The bacterial strains isolated from these aquifers belong predominantly to arsenite-oxidizing bacterial groups. Of these, the membrane-bound phospholipid fatty acids (PLFA) were characterized in seven selected bacterial isolates grown at different concentrations of As(III) in the medium. One of the significant findings of this study is how the increase in external stress can induce alteration of membrane PLFAs. The change in fatty acid saturation and alteration of their steric conformation suggests alteration of membrane fluidity due to change in As-related stress. However, different bacterial groups can have different degrees of alteration that can affect sustainability in As-rich aquifers of the Bengal Delta Plain.
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| 8. |
- Huang, Fang, et al.
(författare)
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Cultivation of the gut bacterium Prevotella copri DSM 18205T using glucose and xylose as carbon sources
- 2021
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Ingår i: MicrobiologyOpen. - : Wiley. - 2045-8827. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Prevotella copri DSM18205T is a human gut bacterium, suggested as a next-generation probiotic. To utilize it as such, it is, however, necessary to grow the species in a reproducible manner. Prevotella copri has previously been reported to be highly sensitive to oxygen, and hence difficult to isolate and cultivate. This study presents successful batch cultivation strategies for viable strain inoculations and growth in both serum bottles and a stirred tank bioreactor (STR), without the use of an anaerobic chamber, as long as the cells were kept in the exponential growth phase. A low headspace volume in the STR was important to reach high cell density. P. copri utilized xylose cultivated in Peptone Yeast Xylose medium (PYX medium), resulting in a comparable growth rate and metabolite production as in Peptone Yeast Glucose medium (PYG medium) in batch cultivations at pH 7.2.Up to 5 g/L of the carbon source was consumed, leading to the production of succinic acid, acetic acid, and formic acid, and cell densities (OD620 nm ) in the range 6-7.5. The highest yield of produced succinic acid was 0.63 ± 0.05 g/g glucose in PYG medium cultivations and 0.88 ± 0.06 g/g xylose in PYX medium cultivations.
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| 9. |
- Isik, E., et al.
(författare)
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Identification of novel arsenic resistance genes in yeast
- 2022
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Ingår i: Microbiologyopen. - : Wiley. - 2045-8827. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Arsenic is a toxic metalloid that affects human health by causing numerous diseases and by being used in the treatment of acute promyelocytic leukemia. Saccharomyces cerevisiae (budding yeast) has been extensively utilized to elucidate the molecular mechanisms underlying arsenic toxicity and resistance in eukaryotes. In this study, we applied a genomic DNA overexpression strategy to identify yeast genes that provide arsenic resistance in wild-type and arsenic-sensitive S. cerevisiae cells. In addition to known arsenic-related genes, our genetic screen revealed novel genes, including PHO86, VBA3, UGP1, and TUL1, whose overexpression conferred resistance. To gain insights into possible resistance mechanisms, we addressed the contribution of these genes to cell growth, intracellular arsenic, and protein aggregation during arsenate exposure. Overexpression of PHO86 resulted in higher cellular arsenic levels but no additional effect on protein aggregation, indicating that these cells efficiently protect their intracellular environment. VBA3 overexpression caused resistance despite higher intracellular arsenic and protein aggregation levels. Overexpression of UGP1 led to lower intracellular arsenic and protein aggregation levels while TUL1 overexpression had no impact on intracellular arsenic or protein aggregation levels. Thus, the identified genes appear to confer arsenic resistance through distinct mechanisms but the molecular details remain to be elucidated.
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| 10. |
- Kaggwa, Mary Nakabungo, et al.
(författare)
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Ecomorphological variability of Arthrospira fusiformis (Cyanoprokaryota) in African soda lakes
- 2013
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Ingår i: MicrobiologyOpen. - : Wiley. - 2045-8827. ; 2:5, s. 881-891
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Tidskriftsartikel (refereegranskat)abstract
- The filamentous spirally coiled cyanoprokaryote Arthrospira fusiformis is found in extremely high densities in tropical soda lakes acting as driving force of the food web. We studied pronounced temporal morphological changes of Arthrospira in Kenyan soda lakes, Nakuru and Bogoria, and identified underlying key factors. Cell (diameter and height) and filament (height of coil, coil diameter, and number) dimensions were measured from weekly samples collected over a period of 16 months. In both lakes, medium-sized cells and large, widely coiled filaments prevailed most. Percentage of large, widely coiled filaments was promoted by elevated levels of soluble reactive phosphorus, wind speed, temperature and conductivity and the opposite for small filaments. Large, narrow-coiled filaments were associated with an increase in mainly Arthrospira-grazing zooplankton and cyanophage infections. Widely coiled spirals were promoted by increased turbulences. Based on fluorescence measurements, we found widely coiled filaments representing high vitality. From this study we were able to demonstrate for the first time morphological patterns of Arthrospira in nature. Arthrospira morphotypes are suitable for indicating the biological status in soda lakes as they are subjective and therefore reflective of what is happening in its habitat. Additionally, this outcome might be also of interest for commercial 'Spirulina' farms in enhancing high-quality production.
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