Centro Científico Tecnológico - Tucumán

The aim of this review is to summarize the effect in host energy metabolism of the production of B group vitamins and short chain fatty acids (SCFA) by commensal, food-grade and probiotic bacteria, which are also actors of the mammalian nutrition. The mechanisms of how these microbial end products, produced by these bacterial strains, act on energy metabolism will be discussed. We will show that these vitamins and SCFA producing bacteria could be used as tools to recover energy intakes by either optimizing ATP production from foods or by the fermentation of certain fibers in the gastrointestinal tract (GIT). Original data are also presented in this work where SCFA (acetate, butyrate and propionate) and B group vitamins (riboflavin, folate and thiamine) production was determined for selected probiotic bacteria.

and to screen large chemical libraries for putative ICD inducers, based on a high-content, high-throughput platform that we recently developed. Such a platform allows for the detection of multiple DAMPs, like cell surface-exposed calreticulin, extracellular ATP and high mobility group box 1 (HMGB1), and/or the processes that underlie their emission, such as endoplasmic reticulum stress, autophagy and necrotic plasma membrane permeabilization. We surmise that this technology will facilitate the development of next-generation anticancer regimens, which kill malignant cells and simultaneously convert them into a cancer-specific therapeutic vaccine.

BACKGROUND: The gastrointestinal tract is one of the most microbiologically active ecosystems that plays a crucial role in the working of the mucosal immune system (MIS). In this ecosystem, the consumed probiotics stimulate the immune system and induce a network of signals mediated by the whole bacteria or their cell wall structure. This review is aimed at describing the immunological mechanisms of probiotics and their beneficial effects on the host. SUMMARY: Once administered, oral probiotic bacteria interact with the intestinal epithelial cells (IECs) or immune cells associated with the lamina propria, through Toll-like receptors, and induce the production of different cytokines or chemokines. Macrophage chemoattractant protein 1, produced by the IECs, sends signals to other immune cells leading to the activation of the MIS, characterized by an increase in immunoglobulin A+ cells of the intestine, bronchus and mammary glands, and the activation of T cells. Specifically, probiotics activate regulatory T cells that release IL-10. Interestingly, probiotics reinforce the intestinal barrier by an increase of the mucins, the tight junction proteins and the Goblet and Paneth cells. Another proposed mechanism of probiotics is the modulation of intestinal microbiota by maintaining the balance and suppressing the growth of potential pathogenic bacteria in the gut. Furthermore, it has been demonstrated that long-term probiotics consumption does not affect the intestinal homeostasis. The viability of probiotics is crucial in the interaction with IECs and macrophages favoring, mainly, the innate immune response. Macrophages and Dendritic cells (DCs) play an important role in this immune response without inducing an inflammatory pattern, just a slight increase in the cellularity of the lamina propria. Besides, as part of the machinery that probiotics activate to protect against different pathogens, an increase in the microbicidal activity of peritoneal and spleen macrophages has been reported. In malnutrition models, such as undernourishment and obesity, probiotic was able to increase the intestinal and systemic immune response. Furthermore, probiotics contribute to recover the histology of both the intestine and the thymus damaged in these conditions. Probiotic bacteria are emerging as a safe and natural strategy for allergy prevention and treatment. Different mechanisms such as the generation of cytokines from activated pro-T-helper type 1, which favor the production of IgG instead of IgE, have been proposed. Key Messages: Probiotic bacteria, their cell walls or probiotic fermented milk have significant effects on the functionality of the mucosal and systemic immune systems through the activation of multiple immune mechanisms.

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.

OBJECTIVE: To assess efficacy and safety of once-daily 8 or 12 mg perampanel, a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist, when added to concomitant antiepileptic drugs (AEDs) in the treatment of drug-resistant partial-onset seizures. METHODS: This was a multicenter, double-blind, placebo-controlled trial (ClinicalTrials.gov identifier: NCT00699972). Patients (≥12 years, with ongoing seizures despite 1-3 AEDs) were randomized (1:1:1) to once-daily perampanel 8 mg, 12 mg, or placebo. Following baseline (6 weeks), patients entered a 19-week double-blind phase: 6-week titration (2 mg/week increments to target dose) followed by a 13-week maintenance period. Percent change in seizure frequency was the primary endpoint; 50% responder rate was the primary endpoint for EU registration. RESULTS: Of 388 patients randomized and treated, 387 provided seizure frequency data. Using this intent-to-treat population over the double-blind phase, the median percent change in seizure frequency was -21.0%, -26.3%, and -34.5% for placebo and perampanel 8 and 12 mg, respectively (p = 0.0261 and p = 0.0158 for 8 and 12 mg vs placebo, respectively). Fifty percent responder rates during the maintenance period were 26.4%, 37.6%, and 36.1%, respectively, for placebo, perampanel 8 mg, and perampanel 12 mg; these differences were not statistically significant for 8 mg (p = 0.0760) or 12 mg (p = 0.0914). Sixty-eight (17.5%) patients discontinued, including 40 (10.3%) for adverse events. Most frequent treatment-emergent adverse events were dizziness, somnolence, irritability, headache, fall, and ataxia. CONCLUSIONS: This trial demonstrated that once-daily, adjunctive perampanel at doses of 8 or 12 mg improved seizure control in patients with uncontrolled partial-onset seizures. Doses of perampanel 8 and 12 mg were safe, and tolerability was acceptable. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that once-daily 8 and 12 mg doses of adjunctive perampanel are effective in patients with uncontrolled partial-onset seizures.

The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as "all descendants of the most recent common ancestor of birds and Triceratops". Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical "competitive" models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian-Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as "prosauropods" and coelophysoids.

The significance of social situations is commonly context-embedded. Although the role of context has been extensively studied in basic sensory processing or simple stimulus-response settings, its relevance for social cognition is unknown. We propose the social context network model (SCNM), a fronto-insular-temporal network responsible for processing social contextual effects. The SCNM may 1) update the context and use it to make predictions, 2) coordinate internal and external milieus, and 3) consolidate context-target associative learning. We suggest the behavioral variant of frontotemporal dementia (bvFTD) as a specific disorder in which the reported deficits in social cognition (e.g., facial recognition, empathy, decision-making, figurative language, theory of mind) can be described as context impairments due to deficits in the SCNM. Disruption of orbitofrontal-amygdala circuit, as well as the frontal, temporal, and insular atrophy in bVFTD, suggests a relationship between context-sensitive social cognition and SCNM. In considering context as an intrinsic part of social cognition, we highlight the need for a situated cognition approach in social cognition research as opposed to an abstract, universal, and decontextualized approach. The assessment of context-dependent social cognition paradigms, the SCNM, and their possible application to neuropsychiatric disorders may provide new insight into bvFTD and other related frontal disorders.

Drawing upon the concept of ‘accumulation by dispossession’, this paper analyses the expansion of agrarian capital in A rgentina. A case study illustrates the social and environmental impacts of the expansion of agribusiness in central A rgentina and the social struggle – both rural and urban – that has arisen to resist this process. Although government policies after the 2001 crisis differ in many ways from those of the 1990s, current agrarian policies are not significantly distinct from those followed during the pre‐crisis neoliberal period. Rather than ‘post‐neoliberal’, the new model could thus be better described as ‘neo‐extractivist’. With the connivance of the state, agribusiness is producing the largest‐ever transformation of natural capital into economic capital in the history of the region. Moreover, the latest policy developments suggest that A rgentina is on the threshold of a new and deeper stage of agrarian capital expansion and wealth concentration, this time operating at a much larger scale.

The grid-based method to identify areas of endemism proposed by Szumik et al. is extended. The improvements include the ability to assign scores of endemicity to sets of disjoint areas, and to have each species contribute more to the score of endemicity of an area, or less, according to how well its distribution matches the area. The modified method also allows for partially overlapping areas; an area partially overlapping with another one of higher score is retained when the set of lower score has a minimum proportion of species endemic to it. Algorithms to evaluate areas of endemism under this criterion are discussed, and implemented in a computer program (NDM). The new algorithms allow evaluation of much larger data sets.

A formal method was developed to determine areas of endemism. The study region is divided into cells, and the number of species that can be considered as endemic is counted for a given set of cells (= area). Thus, the areas with the maximum number of species considered endemic are preferred. This is the first method for the identification of areas of endemism that implements an optimality criterion directly based on considering the aspects of species distribution that are relevant to endemism. The method is implemented in two computer programs, NDM and VNDM, available from the authors.

Many methods are available for the concentration of proteins; however, most are not easily scalable due to costs, the need of specialized instruments and skilled workers or are very time-consuming. Three-phase partitioning (TPP) is a separation technique that has gained a lot of interest due to its rapid, simple and scalable use for concentration, isolation and decontamination of proteins from crude samples with high recovery yields. In the present work, the effect of various parameters of TPP was evaluated to optimize the concentration of proteins from Chlorella pyrenoidosa (CP), is green algae that increasingly being used as food supplements because of its positive impacts on human health. Chlorella pyrenoidosa was cultivated in a closed system under controlled conditions. After reaching maximum growth, the microalgae was harvested, dried and powdered. Afterwards, TPP of CP cell lysate was done to concentrate protein content. To maximize protein concentration, various parameters were optimized such as solvent (t-butanol), ammonium sulphate concentration (40 % w/v), solid load (0.75 g/20 mL), pH (6), incubation time (20 min), slurry to butanol ratio (1:1.5) and enzymatic treatment (combination of Stargen™ and Carezyme™). Also, total starch, cellulose and carbohydrate content before and after the enzymatic treatment were determined to comprehend the impact of enzymatic treatment on protein concentration. Using these optimized parameters, 78.1 % w/w protein concentration was obtained in middle protein concentrate phase. This protein concentrate was characterizedfor proximate composition, colour analysis, water holding capacity, oil-holding capacity, foaming capacity, foam stability, amino acid composition, protein quality and thermal properties. Various process parameters of TPP influence the protein concentration of middle protein concentrate phase. Enzymatically treated biomass also enhanced protein concentration in middle protein concentrate phase. Characterization of protein concentrate revealed the presence high-quality protein. Therefore, it is possible to implement TPP at an industrial scale for protein concentration.

It is estimated 20-25% of the epileptic patients fails to achieve good control with the different antiepileptic drugs (AEDs) treatments, developing refractory epilepsy (RE). Discovered first in cancer, the activity of P-glycoprotein (P-gp) and others ABC transporters as multidrug-resistance-associated proteins (MRPs) and breast cancer resistant protein (BCRP) are directly related with the refractoriness. We have observed the overexpression of these all transporters in the brain of patients with RE, and according with other authors, all these data suggests an active drug efflux from brain. Both constitutive and seizure induced brain P-gp overexpression was also suggested. As confirmation of these clinical evidences, different models of experimental epilepsy have demonstrated P-gp overexpression on blood brain barrier (BBB) and brain parenchyma cells, as astrocytes and neurons. In our model, early P-pg detection in vessel-related cells and later additional P-gp detection in neurons, correlated with the gradual loss of protective effect of phenytoin. The progressive neuronal P-gp expression, depending on intensity and time-constancy of seizure-injury, was in agreement with the development of "P-gp-positive seizure-axis" proposed by Kwan & Brodie, who also showed that the development of RE directly correlated with the number and frequency of seizures before initiation of drug therapy. P-gp expression in excretory organs suggests that P-gp have a central role in drug elimination. Persistent low levels of AEDs in plasma and P-gp brain overexpression in several RE pediatric patients were reported. We also observed in adult RE patients, an increased liver clearance of 99mTc-hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) (a P-gp substrate), and the surgically treated cases showed P-gp brain overexpression. These results suggest the systemic hyperactivity of P-gp in RE patients, including brain P-gp over-expression should be suspected when persistent subtherapeutic levels of AEDs in plasma are detected. P-gp neuronal expression described in both clinical and experimental reports indicates that additional mechanisms could be operative from seizure-affected P-gp-positive neurons, due to AEDs targets are expressed at membrane level. An alternative mechanism was demonstrated in P-gp-expressed cells that exhibit lower membrane potential (Deltapsi(0)=-10 to -20) compared to normal physiological Deltapsi(0) of -60 mV. Under this situation and irrespective to the P-gp pharmacoresistant property or type of drug treatment selected, P-gp-expressed neurons could increase their sensitivity to new seizures perhaps as an epileptogenic mechanism. The understanding of properties of these ABC transporters can offer new tools for better selection of more effective preventive or therapeutic strategies and avoid the invasive surgical treatments for RE.

RATIONALE: Controversy still exists in the international literature regarding the need to use antimicrobials covering atypical pathogens when initially treating hospitalized patients with community-acquired pneumonia (CAP). In different regions of the world, monotherapy with a beta-lactam antimicrobial is common. OBJECTIVES: We sought to correlate the incidence of CAP due to atypical pathogens in different regions of the world with the proportion of patients treated with an atypical regimen in those same regions. In addition, we sought to compare clinical outcomes of patients with CAP treated with and without atypical coverage. METHODS: A secondary analysis was performed using two comprehensive international databases. World regions were defined as North America (I), Europe (II), Latin America (III), and Asia and Africa (IV). Time to reach clinical stability, length of hospital stay, and mortality were compared between patients treated with and without atypical coverage. MEASUREMENTS AND MAIN RESULTS: The incidence of CAP due to atypical pathogens from 4,337 patients was 22, 28, 21, and 20% in regions I-IV, respectively. The proportion of patients treated with atypical coverage from 2,208 patients was 91, 74, 53, and 10% in regions I-IV, respectively. Patients treated with atypical coverage had decreased time to clinical stability (3.7 vs. 3.2 d, p < 0.001), decreased length of stay (7.1 vs. 6.1 d, p < 0.01), decreased total mortality (11.1 vs. 7%, p < 0.01), and decreased CAP-related mortality (6.4 vs. 3.8%, p = 0.05). CONCLUSIONS: The significant global presence of atypical pathogens and the better outcomes associated with antimicrobial regimens with atypical coverage support empiric therapy for all hospitalized patients with CAP with a regimen that covers atypical pathogens.

Tuta absoluta (Meyrick) is an important tomato pest that also feeds on other host-plants from the Solanceae family. We studied the effect of two cultivated plants, tomato (Lycopersicum esculentum Mill.) and potato Solanum tuberosum L. on the development and populational parameters of T. absoluta related with host-plant suitability. Larval developmental time, pupal weight, mean fecundity and an index of host-plant quality (IPQ = pupal weight / frass weight) were estimated. Age-specific survivorship and fecundity life tables were constructed in the laboratory to evaluate the following populational parameters: net reproductive rate (Ro), intrinsic rate of increase (r) and generation time (T). Larval developmental time was shorter and pupal weight was higher (P < 0.0001) for larvae reared on tomato (P < 0.0001). Mean fecundity was not significantly different on both plants (P = 0.07) and food quality of host-plant was higher for tomato (P = 0.02). Mean population parameters on tomato were: Ro = 48.92; T = 27.98, r = 0.14; and on potato: Ro = 14.43; T = 32.35, r = 0.08. Although results showed that tomato was a more suitable host-plant and had a better nutritional quality than potato, when T. absoluta fed on potato the potential population increase requires attention. Under appropriate climatic conditions, spatial and temporal coincidence between crop and pest, T. absoluta could become a pest for the potato crop.

An isolated active region (AR) was observed on the Sun during seven rotations, starting from its birth in July 1996 to its full dispersion in December 1996. We analyse the long-term budget of the AR relative magnetic helicity. Firstly, we calculate the helicity injected by differential rotation at the photospheric level using MDI/SoHO magnetograms. Secondly, we compute the coronal magnetic field and its helicity selecting the model which best fits the soft X-ray loops observed with SXT/Yohkoh. Finally, we identify all the coronal mass ejections (CMEs) that originated from the AR during its lifetime using LASCO and EIT/SoHO. Assuming a one to one correspondence between CMEs and magnetic clouds, we estimate the magnetic helicity which could be shed via CMEs. We find that differential rotation can neither provide the required magnetic helicity to the coronal field (at least a factor 2.5 to 4 larger), nor to the field ejected to the interplanetary space (a factor 4 to 20 larger), even in the case of this AR for which the total helicity injected by differential rotation is close to the maximum possible value. However, the total helicity ejected is equivalent to that of a twisted flux tube having the same magnetic flux as the studied AR and a number of turns in the interval . We suggest that the main source of helicity is the inherent twist of the magnetic flux tube forming the active region. This magnetic helicity is transferred to the corona either by the continuous emergence of the flux tube for several solar rotations (i.e. on a time scale much longer than the classical emergence phase), or by torsional Alfvén waves.

Lactic acid bacteria (LAB) are capable of converting carbohydrate substrates into organic acids (mainly lactic acid) and producing a wide range of metabolites. Due to their interesting beneficial properties, LAB are widely used as starter cultures, as probiotics, and as microbial cell factories. Exploring LAB present in unknown niches may lead to the isolation of unique species or strains with relevant technological properties. Autochthonous rather than allochthonous starter cultures are preferred in the current industry of fermented food products, due to better adaptation and performance of autochthonous strains to the matrix they originate from. In this work, the lactic microbiota of eight different wild tropical types of fruits and four types of flowers were studied. The ability of the isolated strains to produce metabolites of interest to the food industry was evaluated. The presence of 21 species belonging to the genera Enterococcus, Fructobacillus, Lactobacillus, Lactococcus, Leuconostoc, and Weissella was evidenced by using culture-dependent techniques. The isolated LAB corresponded to 95 genotypically differentiated strains by applying rep-PCR and sequencing of the 16S rRNA gene; subsequently, representative strains of the different isolated species were studied for technological properties, such as fast growth rate and acidifying capacity; pectinolytic and cinnamoyl esterase activities, and absence of biogenic amine biosynthesis. Additionally, the strains´ capacity to produce ethyl esters as well as mannitol was evaluated. The isolated fruit- and flower-origin LAB displayed functional properties that validate their potential use in the manufacture of fermented fruit-based products setting the background for the design of novel functional foods.

The globalization of trade and lifestyle ensure that the factors responsible for the emergence of diseases are more present than ever. Despite biotechnology advancements, meat-based foods are still under scrutiny because of the presence of pathogens, which causes a loss of consumer confidence and consequently a fall in demand. In this context, Lactic Acid Bacteria (LAB) as GRAS organisms offer an alternative for developing pathogen-free foods, particularly avoiding Listeria monocytogenes, with minimal processing and fewer additives while maintaining the foods’ sensorial characteristics. The use of LAB strains, enabling us to produce antimicrobial peptides (bacteriocins) in addition to lactic acid, with an impact on quality and safety during fermentation, processing, and/or storage of meat and ready-to-eat (RTE) meat products, constitutes a promising tool. A number of bacteriocin-based strategies including the use of bioprotective cultures, purified and/or semi-purified bacteriocins as well as their inclusion in varied packaging materials under different storage conditions, have been investigated. The application of bacteriocins as part of hurdle technology using non-thermal technologies was explored for the preservation of RTE meat products. Likewise, considering that food contamination with L. monocytogenes is a consequence of the post-processing manipulation of RTE foods, the role of bacteriocinogenic LAB in the control of biofilms formed on industrial surfaces is also discussed.

The induction of a mucosal immune response is not easy due to the development of oral tolerance, but under some conditions, bacteria can activate this immune system. Antigens administered orally can interact with M cells of Peyer's patches or bind to the epithelial cells. We have demonstrated that certain lactic acid bacteria are able to induce specific secretory immunity, and others will enhance the gut inflammatory immune response. The aim of this work was to establish the reason for these different behaviors and to define possible mechanisms involved in the interaction of lactic acid bacteria at the intestinal level. We studied IgA+ and IgM+ B cells comparatively in bronchus and intestine and CD4+ T cells and IgA anti-lactic acid bacteria antibodies in the intestinal fluid, induced by oral administration of Lactobacillus casei, Lb. delbrueckii ssp. bulgaricus, Lb. acidophilus, Lb. plantarum, Lb. rhamnosus, Lactococcus lactis, and Streptococcus salivarius ssp. thermophilus. The increase in the IgA+ B cells in the bronchus means that these lactic acid bacteria were able to induce the IgA cycle by interaction with M cells from Peyer's patches or intestinal epithelial cells. The IgM+ cells increased when the stimulus did not induce the switch from IgM+ to IgA+. The increase in the CD4+ cells suggests interaction of Peyer's patches and enhancement of the B- and T-cell migration. The anti-lactic acid bacteria antibody is related to the processing and presentation of the microorganisms to the immune cells. We demonstrated that Lb. casei and Lb. plantarum were able to interact with Peyer's patch cells and showed an increase in IgA-, CD4+ cells, and antibodies specific for the stimulating strain. Lactobacillus acidophilus induced gut mucosal activation by interaction with the epithelial cells without increase in the immune cells associated with the bronchus. Although Lb. rhamnosus and Strep. salivarius ssp. thermophilus interact with epithelial cells, they also induced an immune response against their epitopes. Lactococcus lactis and Lb. delbrueckii ssp. bulgaricus induced an increase of IgA+ cells entering the IgA cycle but not CD4+ cells; thus, these bacteria would have been bound to epithelial cells that activated B lymphocytes without processing and presenting of their epitopes. We did not determine specific antibodies against Lc. lactis or Lb. bulgaricus.

" transducing elements. Our aim is to show the wide potential of abiotic nanopores in sensing and signal transduction and also to promote the potential of this technology among doctoral students, postdocs, and researchers. We believe that even a casual reader of this perspective will not fail to be impressed by the wealth of opportunities that solid-state nanopores can offer to the transduction of biological, physical and chemical stimuli.

The development of powerful sequencing techniques has allowed, albeit with some biases, the identification and inventory of complex microbial communities that inhabit different body sites or body fluids, some of which were previously considered sterile. Notably, milk is now considered to host a complex microbial community with great diversity. Milk microbiota is now well documented in various hosts. Based on the growing literature on this microbial community, we address here the question of what milk microbiota is. We summarize and compare the microbial composition of milk in humans and in ruminants and address the existence of a putative core milk microbiota. We discuss the factors that contribute to shape the milk microbiota or affect its composition, including host and environmental factors as well as methodological factors, such as the sampling and sequencing techniques, which likely introduce distortion in milk microbiota analysis. The roles that milk microbiota are likely to play in the mother and offspring physiology and health are presented together with recent data on the hypothesis of an enteromammary pathway. At last, this fascinating field raises a series of questions, which are listed and commented here and which open new research avenues.