Water Regulation by Antidiuretic Hormone (ADH)
Data sharing not applicable to this article as no datasets were generated. In nature, bacteria alternate between two modes of growth: a unicellular life phase, in which the cells are free-swimming planktonicand a multicellular life phase, in which the cells are sessile and live in a biofilm, that can be defined as surface-associated microbial heterogeneous structures comprising different populations of microorganisms surrounded by a self-produced matrix that allows their attachment to inert or organic surfaces.
While seeding Tank Prostatahyperplasie Sekretion unicellular life phase allows for bacterial dispersion and the colonization of new environments, biofilms allow sessile cells to live in a coordinated, more permanent manner that favors their proliferation.
In this alternating cycle, bacteria accomplish two physiological transitions seeding Tank Prostatahyperplasie Sekretion differential seeding Tank Prostatahyperplasie Sekretion expression: i from planktonic cells to sessile cells within a biofilm, and ii from sessile to detached, newly planktonic cells. Many of the innate characteristics of biofilm bacteria are of biotechnological interest, such as the synthesis of valuable compounds e. Understanding the ecology of biofilm formation will allow the design of systems that will facilitate making products seeding Tank Prostatahyperplasie Sekretion interest and improve their yields.
While suspensions of bacteria growing in liquid medium have enabled the discovery of the main features of microbial physiology and genetics, in nature bacteria rarely grow as axenic planktonic cultures. Instead, they predominantly exist as communities of sessile cells that develop as biofilms [ 1 — 3 ].
Although most natural or environmental biofilms are highly diverse multi microbial communities, the basic biology of biofilm development has been studied using single-species biofilms [ 5 ]. Biofilm formation is a nearly universal bacterial trait and has several general characteristics. Thus, biofilm development can be divided seeding Tank Prostatahyperplasie Sekretion three distinct stages: attachment, maturation active sessile cellsand release [ 67 ].
In relation with the properties of the surfaces, the factors of a surface that determine initial bacterial attachment are its charge, hydrophobicity, and roughness [ 8 ].
Biofilms do not grow forever: rather, the release of previously sessile cells is an intrinsic part of the surface-associated mode of life and it leads to the formation of new biofilms, often at distant sites [ 9 ]. Bacteria are released from biofilms via desorption, detachment, and dispersion. Desorption is the direct transfer of bacteria from seeding Tank Prostatahyperplasie Sekretion biofilm surface to the surrounding medium; it usually occurs in the early stages of biofilm development.
In dispersion, regulatory systems enable physiological changes that facilitate the release of cells from the biofilm to the medium [ 9 ]. Biofilms offer bacteria several ecological and physiological advantages: Biofilms constitute a protective physical barrier to nonspecific and specific host defenses during infection; they confer tolerance to seeding Tank Prostatahyperplasie Sekretion agents disinfectants and antibiotics by reducing diffusion of those toxic compounds; and they effectively reduce the grazing by protozoa [ 10 — 13 ].
Those protective benefits of biofilms depend on their seeding Tank Prostatahyperplasie Sekretion structure matrixand on the gene expression patterns of sessile cells [ 1214 ]. By providing a stable physical environment for cell to cell contact conjugation or the incorporation of external DNA transformationbiofilms facilitate horizontal gene transfer among the large number of individuals residing within them [ 1216 — 18 ].
The structural integrity of a biofilm depends upon the extracellular matrix ECM produced by its constituent microorganisms. The ECM of bacterial biofilms is a complex mixture of exopolysaccharides, nucleic acids, proteins, and other compounds. Indeed the seeding Tank Prostatahyperplasie Sekretion of the ECM may be as diverse as that of the biofilms themselves, and it contributes significantly to the organization of the community [ 319 ].
Microorganisms in biofilms are metabolically and functionally integrated consortia that can adopt specific spatial configurations; the presence and localization of the different cell types is therefore dynamic [ 20 ]. The consumption by seeding Tank Prostatahyperplasie Sekretion different cell types of resources e. Microbial consortia have played important roles throughout the history of life on Earth, from the microbial mats a type of biofilm that were probably the first ecosystems in the early Archean about — million years agoto the complex microbiota of the intestinal tract of different seeding Tank Prostatahyperplasie Sekretion [ 2124 ].
Cell to cell communication is ubiquitously employed by individual microorganisms as well as microbial communities to coordinate different physiological processes and to initiate cooperative seeding Tank Prostatahyperplasie Sekretion that depend on the production and secretion of small diffusible auto inducers quorum sensing signalssuch as acyl-homoserine lactones, and oligopeptides [ 25 ]. Interactions mediated by inducers form the basis of quorum-sensing, which governs many important physiological processes, such as biofilm development attachment-maturation-detachmentbiodegradation of pollutants, changes in virulence, seeding Tank Prostatahyperplasie Sekretion regulation of metabolic pathways e.
From the human perspective, microbial biofilms can be detrimental or beneficial. Biofilms hinder industrial processes by seeding Tank Prostatahyperplasie Sekretion biofouling, reducing heat transfer, and increasing corrosion. In addition, because they often contain pathogenic and spoilage bacteria resistant to cleaning and disinfecting agents, they pose a risk to public health and compromise the quality of food and non-food products [ 2728 ].
In the medical setting, biofilms cause infections, especially within implants, in the urinary tract and periodontal tissue, and may complicate diseases, such as cystic fibrosis [ 2930 ].
The difficulty in eradicating these infections reflects the antimicrobial tolerance of bacteria protected within biofilms. In fact, the antimicrobial resistance of biofilm bacteria is to fold higher than that of planktonic cells [ 31 ]. In this review, however, we focus on the beneficial applications of biofilms in the biotechnological production of organic compounds and the modification of several foods.
We also consider the possible use of artificially engineered biofilms with increased capabilities designed to yield value-added products.
The bacterial life cycle can be divided into two distinct seeding Tank Prostatahyperplasie Sekretion phases: unicellular planktonic and multicellular biofilm or sessile cells [ 22 ].
Alternation between the two phases requires the transition from planktonic cells to sessile seeding Tank Prostatahyperplasie Sekretion to initiate biofilm formation and from sessile cells to detached cells to allow a return to the planktonic state [ 32 ] Fig. The bacterial life cycle. Unicellular planktonic or free-swimming and multicellular biofilm or sessile cells life phases alternate over time. In this two-phase cycle, bacteria undergo physiological transitions from planktonic cells to sessile cells in building a biofilm, and from sessile cells to dispersed cells in returning to the planktonic state.
Each phase is associated seeding Tank Prostatahyperplasie Sekretion a unique transcriptional behavior.
Sketch by M Berlanga. The differences in gene expression between planktonic cells and biofilm communities include the up-regulation and down-regulation of distinct sets of genes [ 38 ].
For example, genes involved in iron-sulfur metabolism, lipid metabolism, amino acid and carbohydrate transport, biosynthesis of seeding Tank Prostatahyperplasie Sekretion metabolites, and stress response are up-regulated during biofilm formation [ 3338 ], as are genes encoding efflux system components [ 34 ]. In the case of iron metabolism, the iron concentration in the medium is an important seeding Tank Prostatahyperplasie Sekretion signal that induces the expression of adhesion factors, which are critical to the attachment stage of biofilm development.
Accordingly, several genes involved in iron acquisition are over-expressed in the biofilm compared to planktonic cells. The down-regulation of DNA repair genes in biofilm cells indicates that the frequency of spontaneous mutations, and therefore of seeding Tank Prostatahyperplasie Sekretion genetic traits, is elevated within the biofilm [ 38 ].
Cells dispersed from biofilms are transcriptionally closer to their parent cells than to planktonic cells and display specific phenotypes with a high adaptive ability allowing the colonization of new environments [ 33 ].
However, biofilm cells and newly dispersed cells also differ, for example, in their relative expression of genes involved in the SOS response, which are overexpressed in cells of the planktonic growth mode [ 3338 ]. As noted above, the ECM of bacterial biofilms is a complex mixture of exopolysaccharides, nucleic acids, proteins and other seeding Tank Prostatahyperplasie Sekretion that mediate surface adhesion, cell to cell communication, self-organization within the biofilm, structural integrity, nutrient acquisition, and the antibiotic resistance of the bacterial community.
Some of the compounds present in seeding Tank Prostatahyperplasie Sekretion biofilm ECM may be of biotechnological utility for, among others, the cosmetics, food, and pharmaceutical industries. In the following text we examine the potential applications of biofilm surfactants rhamnolipids and the biofilm protein BslA. Microbial surfactants are surface-active metabolites that reduce surface and interfacial tension [ 39 ].
They are produced by microorganisms growing on a variety of substrates and have a diverse group of chemical structures, including glycolipids, lipopeptides and lipoproteins, fatty acids, neutral lipids, and phospholipids, in seeding Tank Prostatahyperplasie Sekretion form of polymers and particles [ 40 ].
Surfactants participate in several key biological functions in different microorganisms, such as substrate uptake [ 41 ], modification of the microbial cell surface [ 41 ], cell motility [ 41 ], and biofilm development [ 42 — 45 ]. Among the better-studied biosurfactants are rhamnolipids, produced mainly by Pseudomonas aeruginosa.
In this species, rhamnolipids play an essential role in the different stages of biofilm development and therefore in the establishment of the biofilm phase of life [ 46 ]. Rhamnolipids are extracellular secondary metabolites with surface-active properties under seeding Tank Prostatahyperplasie Sekretion control of two interrelated quorum-sensing systems: las and seeding Tank Prostatahyperplasie Sekretion [ 47 ].
Low concentrations of rhamnolipids alter cell-surface properties by increasing the hydrophobicity of the cell, which increases its surface affinity and therefore its initial surface adherence [ 404849 ]. However, the overproduction of rhamnolipids inhibits biofilm formation, blocks cellular aggregation, and diminishes secondary colonization onto preformed biofilms by planktonic bacteria [ 43 ].
After adhesion, low concentrations of rhamnolipids are seeding Tank Prostatahyperplasie Sekretion to facilitate the aggregation of P. Later on, in mushroom-shaped mature biofilms, rhamnolipid biosurfactants maintain fluid channels in an open state and thereby support the biofilm itself, by ensuring the flow of nutrients and oxygen into the community and the efflux of waste products [ 43 ].
Davey et al. Finally, the active process of dispersion, in which cell detachment occurs during the late stages of biofilm formation, is also actively mediated by rhamnolipids [ 51 ]. Biosurfactants have been the subject of increasing attention because of their lower toxicity and higher seeding Tank Prostatahyperplasie Sekretion compared to their synthetic chemical counterparts [ 4752 ]. Despite their many commercial applications e.
Better knowledge of the genetics and regulatory pathways underlying surfactant expression is needed to improve the production of biosurfactants [ 47 ].
The persistent resistance to liquid wetting and gas penetration of B. In vivo, amphiphilic BslA localizes to the biofilm surface [ 55 ]. BslA is a member of the family of hydrophobin proteins and its core is structurally similar to that of proteins of the immunoglobulin superfamily [ 53 ] Fig. BslA is important for proper biofilm development, but unlike exopolysaccharides and the amyloid protein TasA it is not directly involved in cell cluster formation [ 56 ].
Moreover, it is synthesized only after the production of exopolysaccharide and amyloid fibers. The disruption of BslA production results in the loss of surface repellency and alters the surface microstructure of the biofilm [ 56 ]. Hydrophobins such as BslA may have applications in the food or cosmetic industry, as stabilizers.
For example, ice cream is a mixture of air, fat, milk proteins, sugar, and water. During ice cream production, BslA protein can be used to combine the air, fat, and water, thus yielding a stable mixture and allowing ice cream to stay frozen for longer periods seeding Tank Prostatahyperplasie Sekretion time, even in hot weather. BslA also retards the growth of ice crystals, ensuring that a smooth texture is maintained [ 58 ]. Biofilms could also be used for the production of various chemicals, whether by fermentation ethanol, butanol, lactic acid, and succinic acid or during wastewater treatment or bioremediation.
Thus far, the biofilms used to obtain industrial products are typically those of single species, seeding Tank Prostatahyperplasie Sekretion allows the controlled growth conditions needed to maximize the production of the desired compound [ 59 — 61 ]. In biofilms seeding Tank Prostatahyperplasie Sekretion for industrial applications biofilm reactorsmicrobial cells are fixed on different supports by adsorption, entrapment, or covalent bond formation.
Adsorption uses the natural ability of bacterial cells to adhere to a support such as charcoal, resin, vermiculite, sand particles, polypropylene. Entrapment consists of active cell immobilization in a polymer matrix such as agar, alginate, polyacrylamide, chitosan, gelatin, collagenwhereas a prerequisite for covalent binding to surfaces is the presence of coupling agents that promote adhesion to the support [ 61 ].
Generally, the most commonly used biofilm bioreactors are fixed by adsorption, as is the case in continuous stirred tank reactors, packed bed reactors, fluidized bed reactors, and airlift reactors [ 5962 — 64 ]. In all of these, an appropriate reactor design and the correct solid support are essential to achieve homogeneous distribution of seeding Tank Prostatahyperplasie Sekretion biofilm and therefore seeding Tank Prostatahyperplasie Sekretion a stable production in the biofilm reactor [ 61 ].
Indeed, seeding Tank Prostatahyperplasie Sekretion advantages of biofilm reactors include their ability to retain 5 to 10 times more biomass per unit volume of reactor, thereby increasing production rates, reducing the risk of seeding Tank Prostatahyperplasie Sekretion washout at high dilution rates during continuous fermentation, and eliminating the need for re-inoculation during repeated-batch fermentation [ 5961 ]. Additionally, biofilms provide a stable environment for the microorganisms enclosed within them, and their ECMs confer a higher resistance to extreme conditions of pH and temperature and the presence of toxic substances [ 6162 ].
Comparison of the synthesis of products by biofilm reactors adhesion to different supports vs. In contrast to natural or laboratory-produced biofilms obtained by adhesion to carrier surfaces or reactor biofilms obtained by adsorption to a supportcells immobilized or entrapped, e. Consequently, the changes in gene expression that normally follow adhesion are absent [ 3365 ]. The porosity of the beads is related to the type and concentration of the alginate.
Therefore, cells located at the center of the beads may face aeration and nutritional limitations [ 68 ]. In beads, it seems that dispersed cells are an eruption of entire microcolonies at once into the surrounding medium [ 6669 — 71 ] Fig. In Halomonas venustathe surface properties Lewis-acid or electron acceptor—donator character of the cells and their hydrophobicity of the dispersed cells clearly differ from those of planktonic cells, and in consequence they may explain their better adhesion on polystyrene [ 74 ].
From [ 74 ], seeding Tank Prostatahyperplasie Sekretion permission. Arrow individual cell protruding from the bumps produced by the presence of microcolonies on the surface of the bead and about seeding Tank Prostatahyperplasie Sekretion detach. As established cell factories, biofilm-detached cells could be a better alternative for PHA production than planktonic cells. Olives are a fruit that contains a bitter component seeding Tank Prostatahyperplasie Sekretionsugar 2.
Because olives are not palatable directly after their harvest, they must be treated before they can be sold to consumers. The final product has improved sensory characteristics and can then be marketed [ 81 ].