142 research outputs found
Fermentation of Microalgal Biomass for Innovative Food Production
Fermentation is an ancient method used worldwide to process and preserve food while
enhancing its nutraceutical profile. Alga‐based fermented products have recently been developed
and tested due to growing interest in healthy sustainable diets, which demands the development of
innovative practices in food production, operating for both human health and Earth sustainability.
Algae, particularly microalgae such as Arthrospira platensis, Chlorella vulgaris, and Dunaliella salina,
are already cultivated as sources of food due to their valuable compounds, including proteins,
pigments, lipids, carotenoids, polyunsaturated fatty acids, steroids, and vitamins. Due to their
nutritional composition, functional diversity, and flexible metabolism, microalgae represent good
fermentation substrates for lactic acid bacteria (LAB) and yeasts. This review presents an overview
of the scientific studies on microalga fermentation underlining microalgae’s properties and health
benefits coupled with the advantages of LAB and yeast fermentation. The potential applications of
and future perspectives on such functional foods are discussed
Innovative Fermented Beverages Made with Red Rice, Barley, and Buckwheat
The increase in food intolerances, allergies, and food-based lifestyle choices has dramatically
increased the consumer demand for healthy foods characterized by pleasant sensory traits.
In such a context, innovative cereal-based beverages are characterized by high nutritional value,
pleasant palatability, and potential healthy properties. In the present study, a pool of 23 lactic acid
bacteria strains was preliminary assayed as monocultures for the fermentation of three ad hoc formulated
cereal- (red rice and barley) and pseudocereal (buckwheat) -based substrates. Eight strains
with the best performance in terms of acidification rate were selected for the formulation of three
multiple strain cultures to be further exploited for the manufacture of laboratory-scale prototypes
of fermented beverages. The compositional and microbiological features of the three experimental
beverages highlighted their high biological value for further exploitation
Exploitation of Tenebrio molitor larvae as biological factories for human probiotics, an exploratory study
The exploitation of yellow mealworm (Tenebrio molitor) larvae for the bioaugmentation of probiotic Bacillus
clausii strains was evaluated during a 7-day rearing period. qPCR was applied to evaluate the persistence
and growth of B. clausii in the rearing substrate and larvae (washed and non-washed). Moreover, the effect
of freeze-drying of larvae on B. clausii viability was evaluated. The results demonstrated the suitability of
yellow mealworm as biological factories for the multiplication of B. clausii through a simple and inexpensive
procedure, in view of the further application of larvae as foods and food ingredients. In more detail, an increase
in the load of B. clausii was observed during the 7-day rearing of larvae fed wheat middlings
spiked with 1 Log cells g−1. Further research is needed to evaluate the most suitable technologies and processing
parameters for obtaining yellow mealworm-based ingredients with a stable and active population of
probiotic B. clausii
Study of the bacterial diversity of foods: PCR-DGGE versus LH-PCR
The present study compared two culture-independent methods, polymerase chain reaction denaturing gradient
gel electrophoresis (PCR-DGGE) and length-heterogeneity polymerase chain reaction (LH-PCR), for their ability
to reveal food bacterial microbiota. Total microbial DNA and RNA were extracted directly from fourteen
fermented and unfermented foods, and domain A of the variable regions V1 and V2 of the 16S rRNA gene was
analyzed through LH-PCR and PCR-DGGE. Finally, the outline of these analyses was compared with bacterial viable
counts obtained after bacterial growth on suitable selective media.
For the majority of the samples, RNA-based PCR-DGGE revealed species that the DNA-based PCR-DGGE was not
able to highlight. When analyzing either DNA or RNA, LH-PCR identified several lactic acid bacteria (LAB) and coagulase
negative cocci (CCN) species that were not identified by PCR-DGGE. This phenomenon was particularly
evident in food samples with viable loads b 5.0 Log cfu g−1
. Furthermore, LH-PCR was able to detect a higher
number of peaks in the analyzed food matrices relative to species identified by PCR-DGGE. In light of these findings,
it may be suggested that LH-PCR shows greater sensitivity than PCR-DGGE. However, PCR-DGGE detected
some other species (LAB included) that were not detected by LH-PCR. Therefore, certain LH-PCR peaks not attributed
to known species within the LH-PCR database could be solved by comparing them with species identified by
PCR-DGGE. Overall, this study also showed that LH-PCR is a promising method for use in the food microbiology
field, indicating the necessity to expand the LH-PCR database, which is based, up to now, mainly on LAB isolates
from dairy produc
Association of chronic hepatitis C with major depressive disorders: irrespective of interferon-alpha therapy
Abstract
Background
Mood and anxiety symptoms in chronic hepatitis C (CHC) may be related to the patient awareness of the diagnosis and prognosis, to side effects induced by interferon (IFN)-alpha treatment, as well as to substance abuse. However, the observation of metabolic alterations in patients with CHC has led to hypothesize a direct effect of hepatitis C virus (HCV) on brain function. This study was aimed at elucidating whether CHC is associated with specific anxiety or mood disorders independently of confounding factors.
Methods
Patient cohort: consecutive patients, 135 with CHC and 76 with chronic hepatitis B (CHB). Exclusion criteria: previous treatment with IFN-alpha, co-infection with HCV and hepatitis B virus, infection with human immunodeficiency virus, drug or alcohol abuse, or malignancies. Controls: subjects without evidence of hepatitis randomly extracted from the database of a previous epidemiological study; they were divided into two groups of 540 (332 males) and 304 (220 males) as controls for patients with CHC and CHB, respectively. The psychiatric diagnosis was formulated by means of the Composite International Diagnostic Interview Simplified carried out by a physician according to DSM-IV criteria.
Results
A higher lifetime prevalence of major depressive disorder (MDD) was observed among CHC compared to CHB or controls. The risk of MDD was not statistically different between CHB and controls. Both the CHC and CHB groups showed a significantly higher frequency of panic disorder when compared to controls. No statistical differences were observed in the prevalence of general anxiety disorder and social phobia when CHC or CHB were compared to controls.
Conclusion
The present study provides the first evidence of an association between CHC and MDD, diagnosed on the basis of well-defined international criteria. This association is independent of treatment with IFN-alpha and is not influenced by substance or alcohol abuse. By contrast, anxiety disorders do not appear to be specifically associated with CHC
Discovering microbiota and volatile compounds of surströmming, the traditional Swedish sour herring
none13noIn this study, the microbiota of ready-to-eat surströmming from three Swedish producers were studied using a combined approach. The pH values of the samples ranged between 6.67±0.01 and 6.98±0.01, whereas their aw values were between 0.911±0.001 and 0.940±0.001. The acetic acid concentration was between 0.289±0.009 g/100 g and 0.556±0.036 g/100 g. Very low concentrations of lactic acid were measured. Viable counting revealed the presence of mesophilic aerobes, mesophilic lactobacilli and lactococci as well as halophilic lactobacilli and lactococci, coagulase-negative staphylococci, halophilic aerobes and anaerobes. Negligible counts for Enterobacteriaceae, Pseudomonadaceae and total eumycetes were observed, whereas no sulfite-reducing anaerobes were detected. Listeria monocytogenes and Salmonella spp. were absent in all samples. Multiplex real-time PCR revealed the absence of the bont/A, bont/B, bont/E, bont/F, and 4gyrB (CP) genes, which encode botulinic toxins, in all the samples analyzed. Metagenomic sequencing revealed the presence of a core microbiota dominated by Halanaerobium praevalens, Alkalibacterium gilvum, Carnobacterium, Tetragenococcus halophilus, Clostridiisalibacter, and Porphyromonadaceae. Psychrobacter celer, Ruminococcaceae, Marinilactibacillus psychrotolerans, Streptococcus infantis and Salinivibrio costicola were detected as minority OTUs. GC-MS analysis of volatile components revealed the massive presence of trimethylamine and sulfur compounds. Moreover, 1,2,4-trithiolane, phenols, ketones, aldehydes, alcohols, esters and long chain aliphatic hydrocarbons were also detected. The data obtained allowed pro-technological bacteria, which are well-adapted to saline environments, to be discovered for the first time. Further analyses are needed to better clarify the extent of the contribution of either the microbiota or autolytic enzymes of the fish flesh in the aroma definition.restrictedLuca Belleggia, Lucia Aquilanti, Ilario Ferrocino, Vesna Milanović, Cristiana Garofalo, Francesca Clementi, Luca Cocolin, Massimo Mozzon, Roberta Foligni, M. Naceur Haouet, Stefania Scuota, Marisa Framboas, Andrea OsimaniBelleggia, Luca; Aquilanti, Lucia; Ferrocino, Ilario; Milanovic, Vesna; Garofalo, Cristiana; Clementi, Francesca; Cocolin, Luca; Mozzon, Massimo; Foligni, Roberta; Naceur Haouet, M.; Scuota, Stefania; Framboas, Marisa; Osimani, Andre
Microbial dynamics in rearing trials of Hermetia illucens larvae fed coffee silverskin and microalgae
In the present study, Hermetia illucens larvae were reared on a main rearing substrate composed of a coffee
roasting byproduct (coffee silverskin, Cs) enriched with microalgae (Schizochytrium limacinum or Isochrysis galbana)
at various substitution levels. The microbial diversity of the rearing substrates, larvae, and frass (excrement
from the larvae mixed with the substrate residue) were studied by the combination of microbial culturing on
various growth media and metataxonomic analysis (Illumina sequencing). High counts of total mesophilic aerobes,
bacterial spores, presumptive lactic acid bacteria, coagulase-positive cocci, and eumycetes were detected.
Enterobacteriaceae counts were low in the rearing diets, whereas higher counts of this microbial family were
observed in the larvae and frass. The microbiota of the rearing substrates was characterized by the presence of
lactic acid bacteria, including the genera Lactobacillus, Leuconostoc and Weissella. The microbiota of the H. illucens
larvae fed Cs was characterized by the dominance of Paenibacillus. H. illucens fed diets containing I. galbana were
characterized by the presence of Enterococcus, Lysinibacillus, Morganella, and Paenibacillus, depending on the
algae inclusion level, while H. illucens fed diets containing S. limacinum were characterized by high relative
abundances of Brevundimonas, Enterococcus, Paracoccus, and Paenibacillus, depending on the algae inclusion level.
Brevundimonas and Alcaligenes dominated in the frass from larvae fed I. galbana; the predominance of Brevundimonas
was also observed in the frass from larvae fed Schyzochitrium-enriched diets. Based on the results of
the present study, an effect of algae nutrient bioactive substances (e.g. polysaccharides, high-unsaturated fatty
acids, taurine, carotenoids) on the relative abundance of some of the bacterial taxa detected in larvae may be
hypothesized, thus opening new intriguing perspectives for the control of the entomopathogenic species and
foodborne human pathogens potentially occurring in edible insects. Further studies are needed to support this
hypothesis. Finally, new information on the microbial diversity occurring in insect frass was also obtained
Investigation of the Dominant Microbiota in Ready-to-Eat Grasshoppers and Mealworms and Quantification of Carbapenem Resistance Genes by qPCR
In this study, 30 samples of processed edible mealworms (Tenebrio molitor L.) and 30 samples of grasshoppers (Locusta migratoria migratorioides) were obtained from producers located in Europe (Belgium and the Netherlands) and Asia (Thailand) and subjected to PCR-DGGE analyses. The PCR-DGGE analyses showed that species in the genus Staphylococcus were predominant in the samples of mealworms from Belgium and grasshoppers from the Netherlands; species in the genus Bacillus were detected in the samples of mealworms and grasshoppers from Thailand. Moreover, Weissella cibaria/confusa/spp. was found in grasshoppers from Belgium. Since data concerning the role of novel foods such as edible insects in the dissemination of carbapenem resistance are currently lacking, the quantification of five carbapenemase encoding genes (blaNDM−1, blaVIM, blaGES, blaOXA−48, and blaKPC) by qPCR was also carried out in all the samples under study. The genes coding for GES and KPC were not detected in the analyzed samples. A very low frequency of blaOXA−48 (3%) and blaNDM−1 (10%) genes was detected among mealworms. In contrast, grasshoppers were characterized by a high incidence of the genes for OXA-48 and NDM-1, accounting for 57 and 27% of the overall grasshopper samples, respectively. The blaVIM gene was detected exclusively in two grasshopper samples from Thailand, showing only 7% positivity. The analysis of variance showed that all the effects (producers, species, and producers × species) were statistically significant for blaNDM−1, whereas for blaOXA−48 and blaVIM, no significant effects were detected for the same source of variation. Further studies are necessary to assess the possible role of edible insects as reservoirs for the resistance to carbapenems and to understand the correlation with the insect microbiota. Furthermore, an intensified surveillance plan examining the occurrence of carbapenemase encoding genes in the food chain and in environmental compartments is needed for a proper risk assessment. In such a context, the appropriate use of antimicrobials represents the main preventive action that should always be applied
Distribution of Transferable Antibiotic Resistance Genes in Laboratory-Reared Edible Mealworms (Tenebrio molitor L.)
In the present study, the distribution of antibiotic resistance genes in laboratory-reared fresh mealworm larvae (Tenebrio molitor L.), their feeding substrates (carrots and wheatmeal), and frass was assessed. Microbial counts on selective media added with antibiotics highlighted the presence of lactic acid bacteria resistant to ampicillin and vancomycin and, more specifically, enterococci resistant to the latter antibiotic. Moreover, staphylococci resistant to gentamicin, erythromycin, tetracycline, and vancomycin were detected. Enterobacteriaceae resistant to ampicillin and gentamicin were also found, together with Pseudomonadaceae resistant to gentamicin. Some of the genes coding for resistance to macrolide-lincosamide-streptogramin B (MLSB) [erm(A), erm(C)], vancomycin [vanA, vanB], tetracycline [tet(O)], and β-lactams [mecA and blaZ] were absent in all of the samples. For the feeding substrates, organic wheatmeal was positive for tet(S) and tet(K), whereas no AR genes were detected in organic carrots. The genes tet(M), tet(K), and tet(S) were detected in both mealworms and frass, whereas gene aac-aph, coding for resistance to amynoglicosides was exclusively detected in frass. No residues for any of the 64 antibiotics belonging to 10 different drug classes were found in either the organic wheatmeal or carrots. Based on the overall results, the contribution of feed to the occurrence of antibiotic resistance (AR) genes and/or antibiotic-resistant microorganisms in mealworm larvae was hypothesized together with vertical transmission via insect egg smearing
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