Live Bacteria Research Articles

Mesophilic and thermophilic anaerobic digestion of animal manure: Integrated insights from biogas productivity, microbial viability and enzymatic activity

Anaerobic digestion (AD) is considered a promising technology for the sustainable management of current large quantities of animal waste. However, the efficiency and underlying mechanisms remain poorly understood, particularly regarding the different characteristics of different types of animal wastes. The present study investigated the methane production, community structure, microbial viability, and enzymatic activity following mesophilic and thermophilic AD of four types of animal waste, including carnivores (lion), herbivores (elephant), and omnivores (hippopotamus and orangutan). Methane yield obtained with thermophilic AD of four animals was higher than mesophilic ones. The methane yields of lion manure under the mesophilic and thermophilic AD were 0.326 L/g VS and 0.391 L/g VS, respectively, higher than that of herbivore and omnivore waste. Bacteria were divided into low-DNA (LDNA) and high-DNA (HDNA) bacteria by flow cytometry based on DNA content. Compared with mesophilic AD, thermophilic AD had higher cells density, which has the same trend with methane production. The results showed that the live LDNA bacteria abundance was increased by 98.6% in orangutan manure AD system after heating up to 55 ℃. However, most of the dead bacteria were HDNA, indicating sensitivity of HDNA cells to environmental conditions. For functional enzymes, the activities of dehydrogenase, phosphotransacetylase and protease were enhanced in the thermophilic AD system of all kinds of animal manure. Nevertheless, the acetate kinase activities of herbivorous animal manure and coenzyme F420 activities of omnivorous animal manure had been inhibited at high temperatures.

Lacticaseibacillus rhamnosus GG Counteracts Rotavirus-Induced Ion Secretion and Enterocyte Damage by Inhibiting Oxidative Stress and Apoptosis Through Specific Effects of Living and Postbiotic Preparations.

BackgroundAdministration of Lacticaseibacillus rhamnosus GG (LGG) to children with gastroenteritis is recommended by universal guidelines. Rotavirus (RV) causes diarrhea through combined cytotoxic and enterotoxic effects. Aim of this study was to evaluate the mechanisms of efficacy of LGG in an in-vitro model of RV diarrhea in its viable form (LGG) and conditioned medium (mLGG).MethodsIon secretion corresponding to the NSP4 enterotoxic effect, was evaluated by short circuit current (Isc) and the cytotoxic effect by transepithelial electrical resistance (TEER) in Ussing chambers, upon exposure to RV in Caco-2 enterocyte monolayers treated or not with living probiotic or its culture supernatant. Mechanisms of enterotoxic and cytotoxic damage were evaluated including oxidative stress measured by reactive oxygen species, apoptosis evaluated by DAPI and nuclear staining, NFkβ immunofluorescence.ResultsRV induced Isc increase and TEER decrease, respectively indicating ion secretion and epithelial damage, the two established pathways of diarrhea. Both probiotic preparations reduced both diarrheal effects, but their potency was different. Live LGG was equally effective on both enterotoxic and cytotoxic effect whereas mLGG was highly effective on ion secretion and showed minimal protective effects on cytoskeleton, apoptosis and NFkβ.ConclusionsLGG counteracts RV-induced diarrhea by inhibiting both cytotoxic and enterotoxic pathogenic mechanisms. Namely, LGG inhibits chloride secretion by specific moieties secreted in the medium with a direct pharmacologic-like action. This is considered a postbiotic effect. Subsequently, live bacteria exert a probiotic effect protecting the enterocyte structure.

Comparison of decontamination efficacy of two electrolyte cleaning methods to diode laser, plasma, and air-abrasive devices.

To compare the in vitro decontamination efficacy of two electrolytic cleaning methods to diode laser, plasma, and air-abrasive devices. Sixty sandblasted large-grit acid-etched (SLA) implants were incubated with 2ml of human saliva and Tryptic Soy Broth solution under continuous shaking for 14days. Implants were then randomly assigned to one untreated control group (n = 10) and 5 different decontamination modalities: air-abrasive powder (n = 10), diode laser (n = 10), plasma cleaning (n = 10), and two electrolytic test protocols using either potassium iodide (KI) (n = 10) or sodium formate (CHNaO2) (n = 10) solution. Implants were stained for dead and alive bacteria in two standardized measurement areas, observed at fluorescent microscope, and analyzed for color intensity. All disinfecting treatment modalities significantly reduced the stained area compared to the untreated control group for both measurement areas (p < 0.001). Among test interventions, electrolytic KI and CHNaO2 treatments were equally effective, and each one significantly reduced the stained area compared to any other treatment modality (p < 0.001). Efficacy of electrolytic protocols was not affected by the angulation of examined surfaces [surface angulation 0° vs. 60° (staining %): electrolytic cleaning-KI 0.03 ± 0.04 vs. 0.09 ± 0.10; electrolytic cleaning-CHNaO2 0.01 ± 0.01 vs. 0.06 ± 0.08; (p > 0.05)], while air abrasion [surface angulation 0° vs. 60° (staining %): 2.66 ± 0.83 vs. 42.12 ± 3.46 (p < 0.001)] and plasma cleaning [surface angulation 0° vs. 60° (staining %): 33.25 ± 3.01 vs. 39.16 ± 3.15 (p < 0.001)] were. Within the limitations of the present in vitro study, electrolytic decontamination with KI and CHNaO2 was significantly more effective in reducing bacterial stained surface of rough titanium implants than air-abrasive powder, diode laser, and plasma cleaning, regardless of the accessibility of the contaminated implant location. Complete bacterial elimination (residual bacteria < 1%) was achieved only for the electrolytic cleaning approaches, irrespectively of the favorable or unfavorable access to implant surface.

Effects of different dietary preparations of Enterococcus faecalis F7 on the growth and intestinal microbiota of Pacific white shrimp ( Litopenaeus vannamei )

A 28-day feeding trial was conducted to evaluate the effects of different dietary preparations of Enterococcus faecalis F7 (blank control (BC), dead bacteria (DB), live bacteria (EF), cell-free extract of E. faecalis F7 (BF) and E. faecalis F7 treated with lithium chloride (Li)) on growth and intestinal microbiota of Litopenaeus vannamei. Results indicated that incorporation of live E. faecalis F7 into diet significantly improved the growth of L. vannamei by increasing weight gain rate (WGR), specific growth rate (SGR) and reducing feed conversion ratio (FCR). High-throughput sequencing data showed that incorporation of various preparations of E. faecalis F7 into diet altered intestinal microbiota richness and diversity in L. vannamei. In particular, live E. faecalis F7 improved the health of shrimp by increasing the abundance of beneficial bacteria and reducing the abundance of detrimental bacteria in the gut tract. Moreover, stability of intestinal microbiota was maintained for more than 7 days when shrimps were fed on basic diet after administration of live E. faecalis F7 for 28 days. These results demonstrate that diet enriched with live E. faecalis F7 promotes the growth and modulates the intestinal microbiota in Pacific white shrimp (L. vannamei).

Intracerebral but Not Peripheral Infection of Live Porphyromonas gingivalis Exacerbates Alzheimer's Disease Like Amyloid Pathology in APP-TgCRND8 Mice.

The impact of oral microbial dysbiosis on Alzheimer’s disease (AD) remains controversial. Building off recent studies reporting that various microbes might directly seed or promote amyloid β (Aβ) deposition, we evaluated the effects of periodontal bacteria (Porphyromonas gingivalis, Treponema denticola) and supragingival commensal (Streptococcus gordonii) oral bacterial infection in the APP-transgenic CRND8 (Tg) mice model of AD. We tracked bacterial colonization and dissemination, and monitored effects on gliosis and amyloid deposition. Chronic oral infection did not accelerate Aβ deposition in Tg mice but did induce alveolar bone resorption, IgG immune response, and an intracerebral astrogliosis (GFAP: glial fibrillary acidic protein). In contrast, intracerebral inoculation of live but not heat-killed P. gingivalis increased Aβ deposition and Iba-1 (ionized calcium-binding adaptor-1) microgliosis after 8 weeks of bacterial infection but not at 4 days. These data show that there may be differential effects of infectious microbes on glial activation and amyloid deposition depending on the species and route of inoculation, and thereby provide an important framework for future studies. Indeed, these studies demonstrate marked effects on amyloid β deposition only in a fairly non-physiologic setting where live bacteria is injected directly into the brain.

A programmable encapsulation system improves delivery of therapeutic bacteria in mice

Living bacteria therapies have been proposed as an alternative approach to treating a broad array of cancers. In this study, we developed a genetically encoded microbial encapsulation system with tunable and dynamic expression of surface capsular polysaccharides that enhances systemic delivery. Based on a small RNA screen of capsular biosynthesis pathways, we constructed inducible synthetic gene circuits that regulate bacterial encapsulation in Escherichia coli Nissle 1917. These bacteria are capable of temporarily evading immune attack, whereas subsequent loss of encapsulation results in effective clearance in vivo. This dynamic delivery strategy enabled a ten-fold increase in maximum tolerated dose of bacteria and improved anti-tumor efficacy in murine models of cancer. Furthermore, in situ encapsulation increased the fraction of microbial translocation among mouse tumors, leading to efficacy in distal tumors. The programmable encapsulation system promises to enhance the therapeutic utility of living engineered bacteria for cancer.

Confocal Laser Scanner Evaluation of Bactericidal Effect of Chitosan Nanodroplets Loaded with Benzalkonium Chloride.

The aim was to evaluate the antibacterial efficacy and penetration depth into dentinal tubules of a solution of chitosan nanodroplets (NDs) loaded with Benzalkonium Chloride (BAK). Seventy-two human single-root teeth with fully formed apex were used. Cylindrical root dentin blocks were longitudinally sectioned and enlarged to a size of a Gates Glidden drill #4. After sterilization, root canals were infected with Enterococcus faecalis ATCC 29212 and further incubated for three weeks. Specimens were assigned to three experimental groups (n = 20), plus positive (n = 6) and negative (n = 6) controls. In the first group, irrigation was achieved with 2 mL of NDs solution loaded with BAK (NDs-BAK), in the second with 2 mL of 5% sodium hypochlorite (NaOCl) and in the last with 2 mL of 2% chlorhexidine (CHX). Specimens were rinsed and vertically fractured. Confocal laser scanning microscopy (CLSM) and viability staining were used to analyze the proportions of dead and live bacteria quantitatively. The volume ratio of red fluorescence (dead) was calculated in 3D reconstructions. Data were analyzed by one-way ANOVA and post hoc Bonferroni tests (p < 0.05). The ratio of red fluorescence over the whole green/red fluorescence resulted in a significant comparison of NDs-BAK with NaOCl (p < 0.01) and NaOCl with CHX (p < 0.01). No differences were found between NDs-BAK and CHX (p > 0.05). The mean depth of efficacy was, respectively: NDs-BAK 325.25 μm, NaOCl 273.36 μm and CHX 246.78 μm with no statistical differences between groups. The NaOCl solution showed the highest antimicrobial efficacy, but nanodroplets with BAK seemed to have the same effect as CHX with a high depth of efficacy.

The Fusaric Acid Derivative qy17 Inhibits Staphylococcus haemolyticus by Disrupting Biofilm Formation and the Stress Response via Altered Gene Expression.

Staphylococcus haemolyticus (S. haemolyticus) is the second most commonly isolated coagulase-negative staphylococcus (CoNS) in patients with hospital-acquired infections. It can produce phenol-soluble modulin (PSM) toxins and form biofilms. Compared with the wealth of information on Staphylococcus aureus and Staphylococcus epidermidis, very little is known about S. haemolyticus. There is an urgent need to find an effective preparation to combat the harm caused by S. haemolyticus infection. Chinese herbs have been utilized to cure inflammation and infectious diseases and have a long history of anticancer function in China. Here, we modified fusaric acid characterized from the metabolites of Gibberella intermedia, an endophyte previously isolated from Polygonum capitatum. This study shows that fusaric acid analogs (qy17 and qy20) have strong antibacterial activity against S. haemolyticus. In addition, crystal violet analyses and scanning electron microscopy observations demonstrated that qy17 inhibited biofilm formation and disrupted mature biofilms of S. haemolyticus in a dose-dependent manner. Additionally, it reduced the number of live bacteria inside the biofilm. Furthermore, the antibiofilm function of qy17 was achieved by downregulating transcription factors (sigB), transpeptidase genes (srtA), and bacterial surface proteins (ebp, fbp) and upregulating biofilm-related genes and the density-sensing system (agrB). To further elucidate the bacteriostatic mechanism, transcriptomic analysis was carried out. The following antibacterial mechanisms were uncovered: (i) the inhibition of heat shock (clpB, groES, groL, grpE, dnaK, dnaJ)-, oxidative stress (aphC)- and biotin response (bioB)-related gene expression, which resulted in S. haemolyticus being unable to compensate for various stress conditions, thereby affecting bacterial growth; and (ii) a reduction in the expression of PSM-beta (PSMβ1, PSMβ2, PSMβ3) toxin- and Clp protease (clpP, clpX)-related genes. These findings could have major implications for the treatment of diseases caused by S. haemolyticus infections. Our research reveals for the first time that fusaric acid derivatives inhibit the expression of biofilm formation-related effector and virulence genes of S. haemolyticus. These findings provide new potential drug candidates for hospital-acquired infections caused by S. haemolyticus.

Intravenous Delivery of Living Listeria monocytogenes Elicits Gasdmermin-Dependent Tumor Pyroptosis and Motivates Anti-Tumor Immune Response.

The facultative intracellular bacterium Listeria monocytogenes (Lmo) has great potential for development as a cancer vaccine platform given its properties. However, the clinical application of Lmo has been severely restricted due to its rapid clearance, compromised immune response in tumors, and inevitable side effects such as severe systemic inflammation after intravenous administration. Herein, an immunotherapy system was developed on the basis of natural red blood cell (RBC) membranes encapsulated Lmo with selective deletion of virulence factors (Lmo@RBC). The biomimetic Lmo@RBC not only generated a low systemic inflammatory response but also enhanced the accumulation in tumors due to the long blood circulation and tumor hypoxic microenvironment favoring anaerobic Lmo colonization. After genome screening of tumors treated with intravenous PBS, Lmo, or Lmo@RBC, it was first found that Lmo@RBC induced extensive pore-forming protein gasdermin C (GSDMC)-dependent pyroptosis, which reversed immunosuppressive tumor microenvironment and promoted a systemic strong and durable anti-tumor immune response, resulting in an excellent therapeutic effect on solid tumors and tumor metastasis. Overall, Lmo@RBC, as an intravenous living bacterial therapy for the selective initiation of tumor pyrolysis, provided a proof-of-concept of live bacteria vaccine potentiating tumor immune therapy.

Spatial distribution of live gut microbiota and bile acid metabolism in various parts of human large intestine

Gut microbiomics is based on analysis of both live and dead cells in the stool. However, to understand the ecology of gut microbiota and their symbiotic relationships with hosts, spatial distribution of live bacteria must be examined. Here, we analyzed the live composition of luminal microbiota (LM) and mucosa-associated microbiota (MAM) in the ascending and descending colons and the rectums of 10 healthy adults and compared it with the total composition. The abundance of Lachnospiraceae in live LM decreased along the gut length and was significantly lower than that in total LM. Contrastingly, the abundance of Bacteroidaceae and Bifidobacteriaceae in live LM was higher than that in total LM, suggesting differences in death rate during gut migration. Live Enterobacteriaceae levels in MAM were significantly higher in rectum than in the ascending and descending colons and in LM. High-performance liquid chromatographic analysis of luminal bile acids revealed that 7α-dehydroxylation occurred towards the rectum. In live LM where a bile acid-inducible gene could be detected, 7α-dehydroxylation rates were higher than those in the group without the gene. Overall, we showed differences in live bacteria composition among three gut sites and between LM and MAM, highlighting the importance of understanding their spatial distribution.

Quantitative Imaging of Bacteriophage Amplification for Rapid Detection of Bacteria in Model Foods.

Rapid detection of bacteria in water and food samples is a critical need. The current molecular methods like real-time PCR can provide rapid detection after initial enrichment. However, these methods require significant preparation steps, specialized facilities to reduce contamination, and relatively expensive reagents. This study evaluates a novel approach for detecting bacteria based on imaging of bacteriophage amplification upon infection of the target host bacteria to mitigate some of these constraints and improve the specificity of discriminating live vs. dead bacteria. Thus, this research leverages the natural ability of lytic bacteriophages to rapidly amplify their genetic material and generate progeny phages upon infecting the host bacterium. This study uses a nucleic acid staining dye, a conventional fluorescence microscope, and quantitative image analysis for imaging the amplification of bacteriophages. The sensitivity and assay time for imaging-based quantification of phage amplification for detecting Escherichia coli were compared with RT-PCR and the standard plaque-forming assay for detection phage amplification in model systems, including coconut water and spinach wash water. The results demonstrate that the imaging approach matches both the sensitivity and speed for detecting E. coli using the RT-PCR method without requiring isolation of nucleic acids, expensive reagents, and specialized facilities. The quantitative imaging results demonstrate the detection of 10 CFU/ml of E. coli in coconut water and simulated spinach wash water with a chemical oxygen demand (COD) of 3,000 ppm within 8 h, including initial enrichment of the bacteria. In summary, the results of this study illustrate a novel phage amplification-based approach for detecting target bacteria in complex food and water samples using simple sample preparation methods and low-cost reagents.

Helicobacter pylori Infection of Primary Human Monocytes Boosts Subsequent Immune Responses to LPS.

Infection with Helicobacter pylori (H. pylori) affects almost half of the world’s population and is a major cause of stomach cancer. Although immune cells react strongly to this gastric bacterium, H. pylori is still one of the rare pathogens that can evade elimination by the host and cause chronic inflammation. In the present study, we characterized the inflammatory response of primary human monocytes to repeated H. pylori infection and their responsiveness to an ensuing bacterial stimulus. We show that, although repeated stimulations with H. pylori do not result in an enhanced response, H. pylori-primed monocytes are hyper-responsive to an Escherichia coli-lipopolysaccharide (LPS) stimulation that takes place shortly after infection. This hyper-responsiveness to bacterial stimuli is observed upon infection with viable H. pylori only, while heat-killed H. pylori fails to boost both cytokine secretion and STAT activation in response to LPS. When the secondary challenge occurs several days after the primary infection with live bacteria, H. pylori-infected monocytes lose their hyper-responsiveness. The observation that H. pylori makes primary human monocytes more susceptible to subsequent/overlapping stimuli provides an important basis to better understand how H. pylori can maintain chronic inflammation and thus contribute to gastric cancer progression.

A specific primed immune response in red palm weevil, Rhynchophorus ferrugineus, is mediated by hemocyte differentiation and phagocytosis

Red palm weevil, Rhynchophorus ferrugineus, is an invasive and destructive pest that causes serious damages to palm trees. Like other invertebrates, red palm weevil relies solely on its innate immune response to fight invading microbes; by definition, innate immunity lacks adaptive characteristics. However, we show here that priming the red palm weevil larvae with heat-killed Bacillus thuringiensis specifically increased survival of the larvae during a secondary lethal infection with live bacteria, and B. thuringiensis primed larvae also showed a higher clearance efficiency for this bacterium, which indicated that the red palm weevil larvae possessed a strong immune priming response. The degree of enhanced immune protection was positively correlated with hemocyte proliferation and the level of phagocytic ability of hemocytes. Moreover, the red palm weevil larvae primed by B. thuringiensis induced the continuous synthesis of serotonin in the hemolymph, which in turn enhanced the phagocytic ability and pathogen clearance ability of the host, representing an important mechanism for the red palm weevil to achieve priming protection. Our findings reveal a specific immune priming of the red palm weevil larvae mediated by the continuous secretion of serotonin, and provide new insights into the mechanisms of invertebrates immune priming.

Next-day detection of viable Listeria monocytogenes by multiplex reverse transcriptase real-time PCR

Listeria monocytogenes continues to be a major challenge for the food industry due to its ubiquity and difficulty to be eliminated from processing facilities. The DNA amplification-based methods can overcome limitations of culture-based methods; however, due to the stability of the DNA, false positive results may occur, associated to the presence of harmless, dead microorganisms. The incorrect assessment of the results will have a huge impact on the producers in terms of stopping the production/distribution, leading to economic losses. In the current study, a multiplex RT-qPCR method was developed. The detection of mRNA allows for the specific detection of live bacteria. Additionally, two genetic targets (hly and actA) were co-amplified for improved specificity, along with an Internal Amplification Control to rule out false negative results due to reaction inhibition. The optimized methodology was evaluated in smoked salmon samples inoculated with different combinations and concentrations of live and dead bacteria. The method demonstrated high sensitivity (LOD50/LOD95 of 1.2/5.1 cfu/25 g). The performance of the method was compared against the reference standard ISO 11290, for which a Cohen's k of 0.94 was obtained, being interpreted as “almost complete concordance” among both methods. In addition, other parameters evaluated included the relative sensitivity, specificity, accuracy, as well as the positive and negative predictive values, all being above 90%. This next-day methodology can significantly reduce the time of analysis of culture-based methods and can specifically detect live L. monocytogenes.

Probiotic Treatment Enhances Pre-feeding Larval Development and Early Survival in Zebrafish Danio rerio.

The growth and development of healthy culture subjects are essential in increasing productivity in the aquaculture industry. A primary determinant of aquatic animal productivity is the ambient microbial population. If an aquatic animal's microbiome is diverse, with bacteria favoring beneficial over pathogenic species, the health and growth of the animal (i.e., fish or crustacean) can be substantially improved. Embryonic and newly hatched Zebrafish Danio rerio larvae were reared in the presence of (1) water from the broodstock culture tank as a control, (2) a probiotic solution containing 19 strains of live lactic acid bacteria (LAB), or (3) an antibiotic (AB) solution with amoxycillin. Developmental parameters were monitored until 10 d postfertilization. Bacteria present in the water and larvae were cultured and identified by sequencing the V4 hypervariable region of bacterial 16S ribosomal RNA. Probiotic-treated larvae showed significant increases in every measured morphological parameter and in survival compared to the controls and AB-treated larvae, including TL, eye development, and swim bladder development before first feeding. Staining with DASPEI (2-(4-[dimethylamino]styryl)-N-ethylpyridinium iodide) produced fluorescence, revealing increased mitochondrial activity in the gastrointestinal tracts of probiotic-treated larvae and reflecting advancement of initial metabolic function. Probiotic-treated larvae showed accelerated yolk absorption, resulting in increased nutrient mobilization and growth. Microbial analyses revealed a greater concentration of bacteria in larvae in response to the probiotic treatment compared to the other two treatments. Species identified in all three treatments included Pseudomonas spp. and Aeromonas spp. (Proteobacteria). The second most diverse and abundant microbiome was seen in controls, whereas AB-treated larvae had the least diverse microbiome. All treatments revealed the presence of proteobacteria, but an AB-resistant pathogenic bacterium (Stenotrophomonas maltophilia) was identified in the AB group. These results reveal that the presence of LAB and other bacteria favorably influenced early larval growth, development, digestive function, and survival in Zebrafish even before the onset of feeding.

Changes in the microbiome during oral wound healing

• Given that microbes in the oral cavity can impact health and disease, manipulating the oral microbiome may be a viable option in health. • Results demonstrate that identifying candidate beneficial microbes that promote oronasal fistula healing is critical to developing new therapies that promote healing. • Overuse of antibiotics during oronasal fistula repair surgery has significant long -term effects in pediatric populations. • Use of novel methodologies for delivering probiotics to oral wounds using hydrogel and porous scaffold technologies are clearly warranted. • Improving oral wound healing may limit the devastating impact of oronasal fistulas on the quality of life of children. The microbiome is a numerically vast and taxonomically diverse microbial community that includes bacteria, fungi and viruses. The microbiome inhabits all exposed surfaces of the body and exist in a symbiosis with the host in health individuals. The microbiome can affect normal physiology of a number of host organs and systems, while a disturbance in the microbiota community structure, or failure of host responsive mechanisms to the microbiome have been implicated in a variety of disease etiologies. One of the least well-funded areas of microbiota research in relation to health and disease is the community of microbes that inhabits the oral cavity. Here, we outline the importance of the influence of the oral microbiome on healthy oral tissue homeostasis, the therapeutic options of treatment with live bacteria for diseased states within the oral cavity, and how the oral microbiome may influence healing of oral wounds resulting from oroantral and oronasal fistulas. In addition, we discuss the oral microbiome in relation to its influence on bodily organs distant from the alimentary canal, and on systemic health and disease.

Detection of Bacterial α-l-Fucosidases with an Ortho-Quinone Methide-Based Probe and Mapping of the Probe-Protein Adducts.

Fucosidases are associated with several pathological conditions and play an important role in the health of the human gut. For example, fucosidases have been shown to be indicators and/or involved in hepatocellular carcinoma, breast cancer, and helicobacter pylori infections. A prerequisite for the detection and profiling of fucosidases is the formation of a specific covalent linkage between the enzyme of interest and the activity-based probe (ABP). The most commonly used fucosidase ABPs are limited to only one of the classes of fucosidases, the retaining fucosidases. New approaches are needed that allow for the detection of the second class of fucosidases, the inverting type. Here, we report an ortho-quinone methide-based probe with an azide mini-tag that selectively labels both retaining and inverting bacterial α-l-fucosidases. Mass spectrometry-based intact protein and sequence analysis of a probe-labeled bacterial fucosidase revealed almost exclusive single labeling at two specific tryptophan residues outside of the active site. Furthermore, the probe could detect and image extracellular fucosidase activity on the surface of live bacteria.

Chocolate as Prebiotic and Probiotic Delivery Vehicle

In today’s world, food, besides their basic role in nutrition, has to meet additional aspects such as maintenance of health and to counteract diseases. Scientific research refers to health benefits of probiotics and prebiotics in human nutrition. An increasing demand of consumers for foodstuffs supplemented with live probiotic bacteria, gave rise to studies on the development of foods with these microorganisms. However, the possible applications of probiotics in non-dairy food products have not studied well. This study explores the new product, chocolate as a delivery vehicle for pre and probiotics. Probiotic chocolates were made using microencapsulated Lactobacillus strains along with fruit pulp to serve as prebiotics. The confirmatory tests for probiotics, sensory properties and shelf life were studied. The results revealed that the probiotic chocolate prepared with the incorporation of fruit extract like Passion fruit and Strawberry fruit rated the maximum by the consumers through sensory evaluation and the product has shelf-life of twenty days at room temperature without losing any organoleptic properties

The ZVI-Fenton process affects the total load of human pathogenic bacteria in wastewater samples

We investigated the performance of a heterogeneous Fenton-like reaction (ZVI-Fenton, i.e., ZVI + H2O2, where ZVI = zero-valent iron) towards the removal of potentially pathogenic bacteria in wastewater (WW). The effectiveness of the process was investigated towards live bacteria (measured by flow cytometry) as well as potentially pathogenic bacteria (identified by 16S rRNA amplicon sequencing), antibiotic resistance genes and class 1 integrons (assessed by qPCR). The ZVI-Fenton process resulted about as effective as H2O2 alone to decrease live bacteria (p > 0.05), if compared with the blank controls (neither ZVI nor H2O2, p = 0.00005), although it did not reduce the relative abundance of the tested antibiotic resistance genes or class 1 integrons (p > 0.05). However, ZVI-Fenton was quite effective in lowering the total content of the potentially pathogenic bacteria in WW when compared to the controls with H2O2 (p = 0.0186) and without H2O2 (p = 0.0252). These findings suggest that ZVI-Fenton has potential as an effective WW treatment technique that should be further investigated for future application in WWTPs.

Interfacial Biomaterial-Dentin Bacterial Biofilm Proliferation and Viability Is Affected by the Material, Aging Media and Period.

Biomaterial–dentin interfaces undergo degradation over time, allowing salivary, tissue fluid, and bacterial movement between the root filling or restoration and dentin. This study aims to investigate the effect of aging in simulated human salivary/bacterial/blood esterases (SHSE) on proliferation and viability of Enterococcus faecalis biofilm within the dentin interface with four materials used to fill/restore the endodontic space. Root canals of human anterior teeth were prepared and filled with gutta-percha and one of the following: self-cured resin composite (BisfilTM 2B, Bisco, Schaumburg, IL, USA) with either self-etch (SE) (EasyBond) or total-etch (TE) (ScotchbondTM, 3M, Saint Paul, MN, USA) methacrylate-based adhesives, epoxy-resin sealer (AH Plus®, Dentsply Sirona, York, PA, USA), or bioceramic sealer (EndoSequence® BC Sealer™, Brasseler USA, Savannah, GA, USA). Specimens were aged in SHSE or phosphate-buffered saline (PBS) for up to 360 days, followed by cultivation of steady-state E. faecalis biofilm. Depth and viability of interfacial bacterial biofilm proliferation were assessed by confocal laser scanning microscopy and live/dead staining. Data were analyzed using three-way ANOVA and Scheffe’s post hoc analyses. Initial depths of biofilm proliferation were similar among material groups (p > 0.05). All groups showed significantly deeper biofilm proliferation with increased aging period (p < 0.05). SHSE aging increased interfacial biofilm depth for TE, SE and BC (p < 0.05) but not AH. For unaged interfaces, BC exhibited the lowest ratio of live bacteria, followed by AH, TE, and SE (p < 0.05). Interfacial bacterial biofilm proliferation and viability were dependent on the biomaterial, aging media, and period.