Pigments such as melanin, scytonemin and carotenoids protect microbial cells against the harmful effects of ultraviolet (UV) radiation. The role in UV protection has never been assigned to the ...prodigiosin pigment. In this work, we demonstrate that prodigiosin provides a significant level of protection against UV stress in
Vibrio
sp. DSM 14379. In the absence of pigment production,
Vibrio
sp. was significantly more susceptible to UV stress, and there was no difference in UV survival between the wild-type strain and non-pigmented mutant. The pigment’s protective role was more important at higher doses of UV irradiation and correlated with pigment concentration in the cell. Pigmented cells survived high UV exposure (324 J/m
2
) around 1,000-fold more successfully compared to the non-pigmented mutant cells. Resistance to UV stress was conferred to the non-pigmented mutant by addition of exogenous pigment extract to the growth medium. A level of UV protection equivalent to that exhibited by the wild-type strain was attained by the non-pigmented mutant once the prodigiosin concentration had reached comparable levels to those found in the wild-type strain. In co-culture experiments, prodigiosin acted as a UV screen, protecting both the wild-type and non-pigmented mutants. Our results suggest a new ecophysiological role for prodigiosin.
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Despite a considerable interest in prodigiosin, the mechanism of its antibacterial activity is still poorly understood. In this work, Escherichia coli cells were treated with prodigiosin to determine ...its antimicrobial effect on bacterial physiology. The effect of prodigiosin was concentration dependent. In prodigiosin treated cells above MIC value no significant DNA damage or cytoplasmic membrane disintegration was observed. The outer membrane, however, becomes leaky. Cells had severely decreased respiration activity. In prodigiosin treated cells protein and RNA synthesis were inhibited, cells were elongated but could not divide. Pre-treatment with prodigiosin improved E. coli survival rate in media containing ampicillin, kanamycin and erythromycin but not phleomycin. The results suggest that prodigiosin acts as a bacteriostatic agent in E. coli cells. If prodigiosin was diluted, cells resumed growth. The results indicate that prodigiosin has distinct mode of antibacterial action in different bacteria.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Microbial ecophysiology of Vibrio ruber Danevcic, Tjasa; Boric, Maja; Stopar, David
Food technology and biotechnology,
04/2014, Volume:
52, Issue:
2
Journal Article
Peer reviewed
Open access
Bacteria use different adaptation strategies to survive environmental perturbations. In this minireview, adaptation strategies of new red-pigmented Vibrio ruber isolated from coastal environments to ...different environmental stresses are reviewed. To cope with environmental stresses Vibrio ruber uses several different adaptive strategies. Vibrio ruber membrane has no hydroxy fatty acids, but exceptionally high lysolipid content compared to other related Vibrio species. Inorganic nutrient uptake by bacteria is selective, depends on environmental conditions and varies several fold with environmental perturbations. Protein composition, carbon flow through the central metabolic pathways, energy generation as well as secondary metabolite production adapt readily to stress conditions. The activity of glucose-6-phosphate dehydrogenase proved to be a good indicator of Vibrio ruber stress. Cells are able to modulate their local viscosity in response to variations of environmental viscosity. The bacterium harbours several viral genetic elements in its genome, which could be induced by mitomycin C. Environmental conditions during growth of bacteria have a significant effect on lysate carbon turnover.
Prodigiosin produced by marine bacterium Vibrio ruber DSM 14379 exhibits a potent antimicrobial activity against a broad range of Gram positive and Gram negative bacteria. The mechanism of ...prodigiosin antimicrobial action, however, is not known. In this work, the effect of prodigiosin on Bacillus subtilis growth, cell membrane leakage, and induction of autolysins was studied. Treating B. subtilis with prodigiosin resulted in rapid decline of optical density and increased cell membrane leakage measured by β-galactosidase activity. Cell lysis was initiated immediately after treatment with prodigiosin in the middle exponential phase and was completed within 2 h. Lytic activity of prodigiosin in mutant strains with impaired autolysin genes lytABCD decreased for 80% compared to the wild type strain, while in lytABCDEF mutant strain prodigiosin had no bacteriolytic but only bacteriostatic effect. Fast prodigiosin lytic activity on individual B. subtilis cells was confirmed by a modified comet assay. The results indicate that prodigiosin autolysin induction in B. subtilis is growth phase dependent.
Little is known about metabolic activity of bacteria, when viscosity of their environment changes. In this work, bacterial metabolic activity in media with viscosity ranging from 0.8 to 29.4 mPas was ...studied. Viscosities up to 2.4 mPas did not affect metabolic activity of Vibrio ruber. On the other hand, at 29.4 mPas respiration rate and total dehydrogenase activity increased 8 and 4-fold, respectively. The activity of glucose-6-phosphate dehydrogenase (GPD) increased up to 13-fold at higher viscosities. However, intensified metabolic activity did not result in faster growth rate. Increased viscosity delayed the onset as well as the duration of biosynthesis of prodigiosin. As an adaptation to viscous environment V. ruber increased metabolic flux through the pentose phosphate pathway and reduced synthesis of a secondary metabolite. In addition, V. ruber was able to modify the viscosity of its environment.
Pigments such as melanin, scytonemin and carotenoids protect microbial cells against the harmful effects of ultraviolet (UV) radiation. The role in UV protection has never been assigned to the ...prodigiosin pigment. In this work, we demonstrate that prodigiosin provides a significant level of protection against UV stress in Vibrio sp. DSM 14379. In the absence of pigment production, Vibrio sp. was significantly more susceptible to UV stress, and there was no difference in UV survival between the wild-type strain and non-pigmented mutant. The pigment's protective role was more important at higher doses of UV irradiation and correlated with pigment concentration in the cell. Pigmented cells survived high UV exposure (324 J/m²) around 1,000-fold more successfully compared to the non-pigmented mutant cells. Resistance to UV stress was conferred to the non-pigmented mutant by addition of exogenous pigment extract to the growth medium. A level of UV protection equivalent ot that exhibited by the wild-type strain was attained by the non-pigmented mutant once the prodigiosin concentration had reached comparable levels to those fond in the wild-type strain. In co-culture experiments, prodigiosin acted as a UV screed, protectin both the wild-type and non-pigmented mutants. Our results suggest a new ecophysiological role for prodigiosin. '
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BFBNIB, EMUNI, NMLJ, NUK, PNG, SAZU, SBMB, SBNM, UL, UM, UPUK
Bakterije se na različite načine prilagođavaju promjenama uvjeta okoline. U ovom su kratkom preglednom radu opisane različite strategije prilagodbe crveno pigmentirane bakterije Vibrio ruber, nedavno ...izolirane iz priobalja, na čimbenike stresa (tj. salinitet, viskoznost, UV svjetlost, mitomicin C, pristupačnost hranjiva i temperaturu). Bakterija Vibrio ruber se koristi različitim strategijama adaptacije kako bi se oduprla okolišnom stresu. Ovisno o koncentraciji soli, bakterija Vibrio ruber mijenja svoj lipidni sastav, te svojstva lipidne faze. Membrana se bakterije Vibrio ruber razlikuje od ostalih srodnih vrsta bakterije Vibrio po tome što ne sadržava hidroksi masne kiseline, ali zato ima izrazito velik udjel lizolipida. Nakupljanje anorganskih hranjivih tvari u bakteriji je selektivno i ovisi o uvjetima okoline. Bakterije se brzo prilagođavaju stresnim uvjetima i mijenjaju svoj proteinski sastav, metabolizam, tj. potrošnju ugljika i energije, te proizvodnju sekundarnih metabolita. Aktivnost glukoza-6-fosfat dehidrogenaze dobar je indikator stresa u Vibrio ruber. Bakterije mogu mijenjati viskozitet stanica kao odgovor na promjenu viskoziteta okoline. Imaju nekoliko virusnih elemenata u genomu koji se mogu inducirati mitomicinom C. Promjene u uvjetima okoline tijekom rasta bakterija bitno utječu na iskorištenje ugljika iz lizata mikrobnih stanica. Nedavno je otkrivena nova ekofiziološka funkcija sekundarnog metabolita prodigiozina, a to je da štiti stanicu od UV zračenja. Može se zaključiti da se u kratkom periodu istraživanja bakterije Vibrio ruber (kraćem od deset godina) dokazalo da se može upotrijebiti kao vrlo učinkovit model za ispitivanje ekofiziologije bakterija.
The main objective of this study was to produce the functionally improved whey protein hydrolysate with high bioaccessible antioxidant activity. The hydrolysate with highest antioxidant activity, ...mainly composed of hydrophilic antioxidant peptides and suitable for preventing oxidation in polar food matrices, was produced by tryptic hydrolysis conducted at 37 °C and an enzyme/substrate (E/S) ratio of 0.5%. The hydrolysate exerted significantly improved antioxidant activity (80.0%), digestibility (95.9%) and bioaccessibility (124.6%) compared to the native whey proteins (32.1%, 87.1% and 106.3%, respectively) as widely used food supplement. The high bioaccessibility indicates the preservation of hydrolysate bioactivity during the process of gastrointestinal digestion, as a particular challenge in its application.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
One of the most economical ways of whey processing is the production of
beverages, that represents a single process that exploits all the potential
of whey as a raw material. Functional and sensory ...characteristics of whey
based beverages are a criterion that is crucial to the marketing of products
and win over consumers. The aim of this study was to determine nutritional
and functional characteristics of fermented whey beverage with milk and
commercial ABY-6 culture. The results showed that the applied starter culture
can be used for the production of fermented whey based beverage with
satisfactory nutritional properties. Addition of milk was important not only
in the nutritional quality of the resulting product, but also improved the
taste, the homogeneity and stability. Analysis of the chemical composition of
fermented whey based beverage and nutritional information about it indicates
that the product is a good source of protein and calcium. Fermented beverage
contained 8.07 log (CFU/mL), showed antioxidant activity of at least 38.1%
and the titratable acidity of 28.2?SH corresponding to the acidity of the
product in this category.
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