Acetic acid bacteria in agro-wastes: from cheese whey and olive mill wastewater to cellulose.

In this study, cheese whey and olive mill wastewater were investigated as potential feedstocks for producing bacterial cellulose by using acetic acid bacteria strains. Organic acids and phenolic compounds composition were assayed by high-pressure liquid chromatography. Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction were used to investigate modifications in bacterial cellulose chemical and morphological structure. Cheese whey was the most efficient feedstock in terms of bacterial cellulose yield (0.300 g of bacterial cellulose/gram of carbon source consumed). Bacterial cellulose produced in olive mill wastewater presented a more well-defined network compared to pellicles produced in cheese whey, resulting in a smaller fiber diameter in most cases. The analysis of bacterial cellulose chemical structure highlighted the presence of different chemical bonds likely to be caused by the adsorption of olive mill wastewater and cheese whey components. The crystallinity ranged from 45.72 to 80.82%. The acetic acid bacteria strains used in this study were characterized by 16S rRNA gene sequencing, allowing to assign them to Komagataeibacter xylinus and Komagataeibacter rhaeticus species. This study proves the suitability to perform sustainable bioprocesses for producing bacterial cellulose, combining the valorisation of agro-wastes with microbial conversions carried out by acetic acid bacteria. The high versatility in terms of yield, morphology, and fiber diameters obtained in cheese whey and olive mill wastewater contribute to set up fundamental criteria for developing customized bioprocesses depending on the final use of the bacterial cellulose. KEY POINTS: • Cheese whey and olive mill wastewater can be used for bacterial cellulose production. • Bacterial cellulose structure is dependent on the culture medium. • Komagataeibacter strains support the agro-waste conversion in bacterial cellulose.

Bioconservation of iron and enhancement of antioxidant and antibacterial properties of chicken gizzard protein hydrolysate fermented by Pediococcus acidilactici ATTC 8042.

BACKGROUND: The poultry industry is one of the fastest growing sectors, and it generates considerable quantities of chicken gizzards (CG) every day. However, due to their hard texture and high microbial load, and due to cultural beliefs, they are not preferred by consumers. Chicken gizzards are a substantial source of proteins, iron, and other nutrients, which can be used effectively to produce nutraceuticals, rich in peptides (antioxidants and antibacterial), bio-iron, essential free amino acids, and fatty acids vital for human health. RESULTS: Lactic acid fermentation of CG by Pediococcus acidilactici ATTC 8042 increased the antioxidant activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH), azino-bis (3-ethylbenzothiaziline-6-sulphonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) by up to 26 times compared with unfermented CG (P < 0.05). The amount of hydrolysis and solvents (ethanol and water) used for extracting protein hydrolysates significantly affected the antioxidant properties. Moreover, fermented CG showed a negligible reduction in bio-iron (2-3%) compared with heat-processed CG (85 °C for 15 min), in which bio-iron was reduced by up to 20.3% (P < 0.05). The presence of unsaturated fatty acids such as C20:4 and C22:4 n-6 indicated a low level of lipid oxidation. CONCLUSION: Fermented CG, with its reasonably high antioxidant and antibacterial activity, together with a substantial amount of bio-iron and other nutritional components can serve as a functional food or feed additive to reduce oxidative stress and to treat iron deficiency. © 2020 Society of Chemical Industry.

Valorization of cheese whey using microbial fermentations.

Cheese whey (CW), the liquid resulting from the precipitation and removal of milk casein during cheese-making, and the second cheese whey (SCW) derived from the production of cottage and ricotta cheeses are the main byproducts of dairy industry. The major constituent of CW and SCW is lactose, contributing to the high BOD and COD content. Because of this, CW and SCW are high-polluting agents and their disposal is still a problem for the dairy sector. CW and SCW, however, also consist of lipids, proteins, and minerals, making them useful for production of various compounds. In this paper, microbial processes useful to promote the bioremediation of CW and SCW are discussed, and an overview on the main whey-derived products is provided. Special focus was paid to the production of health-promoting whey drinks, vinegar, and biopolymers, which may be exploited as value-added products in different segments of food and pharmaceutical industries.

Genome sequencing and phylogenetic analysis of K1G4: a new Komagataeibacter strain producing bacterial cellulose from different carbon sources.

OBJECTIVE: The objective of this study was to evaluate the ability of a new Komagataeibacter xylinus strain in producing bacterial cellulose from glucose, mannitol and glycerol, and to assess the genome sequencing with special focus on bacterial cellulose related genes. RESULTS: Bacterial cellulose production during 9 days of cultivation was tested in glucose, mannitol and glycerol, respectively. Differences in the bacterial cellulose kinetic formation was observed, with a final yield of 9.47 g/L in mannitol, 8.30 g/L in glycerol and 7.57 g/L in glucose, respectively. The draft genome sequencing of K1G4 was produced, revealing a genome of 3.09 Mbp. Two structurally completed cellulose synthase operons and a third copy of the catalytic subunit of cellulose synthase were found. By using phylogenetic analysis, on the entire rRNA operon sequence, K1G4 was found to be closely related to Komagataeibacter xylinus LMG 1515T and K. xylinus K2G30. CONCLUSIONS: The different yields of bacterial cellulose produced on glucose, mannitol and glycerol can be correlated with the third copy of bcsAB operon harboured by K1G4, making it a versatile strain for industrial applications.

Activation of the Aromatic Core of 3,3'-(Pyridine-2,6-diylbis(1H-1,2,3-triazole-4,1-diyl))bis(propan-1-ol)-Effects on Extraction Performance, Stability Constants, and Basicity.

The "CHON" compatible water-soluble ligand 3,3'-(pyridine-2,6-diylbis(1H-1,2,3-triazole-4,1-diyl))bis(propan-1-ol) (PTD) has shown promise for selectively stripping actinide ions from an organic phase containing both actinide and lanthanide ions, by preferential complexation of the former. Aiming at improving its complexation properties, PTD-OMe was synthesized, bearing a methoxy group on the central pyridine ring, thus increasing its basicity and hence complexation strength. Unfortunately, solvent extraction experiments in the range of 0.1-1 mol/L nitric acid proved PTD-OMe to be less efficient than PTD. This behavior is explained by its greater pKa value (pKa = 2.54) compared to PTD (pKa = 2.1). This counteracts its improved complexation properties for Cm(III) (log ß3(PTD-OMe) = 10.8 ± 0.4 versus log ß3(PTD) = 9.9 ± 0.5).

The puzzling issue of silica toxicity: are silanols bridging the gaps between surface states and pathogenicity?

BACKGROUND: Silica continues to represent an intriguing topic of fundamental and applied research across various scientific fields, from geology to physics, chemistry, cell biology, and particle toxicology. The pathogenic activity of silica is variable, depending on the physico-chemical features of the particles. In the last 50 years, crystallinity and capacity to generate free radicals have been recognized as relevant features for silica toxicity. The 'surface' also plays an important role in silica toxicity, but this term has often been used in a very general way, without defining which properties of the surface are actually driving toxicity. How the chemical features (e.g., silanols and siloxanes) and configuration of the silica surface can trigger toxic responses remains incompletely understood. MAIN BODY: Recent developments in surface chemistry, cell biology and toxicology provide new avenues to improve our understanding of the molecular mechanisms of the adverse responses to silica particles. New physico-chemical methods can finely characterize and quantify silanols at the surface of silica particles. Advanced computational modelling and atomic force microscopy offer unique opportunities to explore the intimate interactions between silica surface and membrane models or cells. In recent years, interdisciplinary research, using these tools, has built increasing evidence that surface silanols are critical determinants of the interaction between silica particles and biomolecules, membranes, cell systems, or animal models. It also has become clear that silanol configuration, and eventually biological responses, can be affected by impurities within the crystal structure, or coatings covering the particle surface. The discovery of new molecular targets of crystalline as well as amorphous silica particles in the immune system and in epithelial lung cells represents new possible toxicity pathways. Cellular recognition systems that detect specific features of the surface of silica particles have been identified. CONCLUSIONS: Interdisciplinary research bridging surface chemistry to toxicology is progressively solving the puzzling issue of the variable toxicity of silica. Further interdisciplinary research is ongoing to elucidate the intimate mechanisms of silica pathogenicity, to possibly mitigate or reduce surface reactivity.

Role of the Open-Shell Character on the Pressure-Induced Conductivity of an Organic Donor-Acceptor Radical Dyad.

Single-component conductors based on neutral organic radicals have received a lot of attention due to the possibility that the unpaired electron can serve as a charge carrier without the need of a previous doping process. Although most of these systems are based on delocalized planar radicals, we present here a nonplanar and spin localized radical based on a tetrathiafulvalene (TTF) moiety, linked to a perchlorotriphenylmethyl (PTM) radical by a conjugated bridge, which exhibits a semiconducting behavior upon application of high pressure. The synthesis, electronic properties, and crystal structure of this neutral radical TTF-Ph-PTM derivative (1) are reported and implications of its crystalline structure on its electrical properties are discussed. On the other hand, the non-radical derivative (2), which is isostructural with the radical 1, shows an insulating behavior at all measured pressures. The different electronic structures of these two isostructural systems have a direct influence on the conducting properties, as demonstrated by band structure DFT calculations.

Biotechnological production of cellulose by acetic acid bacteria: current state and perspectives.

Bacterial cellulose is an attractive biopolymer for a number of applications including food, biomedical, cosmetics, and engineering fields. In addition to renewability and biodegradability, its unique structure and properties such as chemical purity, nanoscale fibrous 3D network, high water-holding capacity, high degree of polymerization, high crystallinity index, light transparency, biocompatibility, and mechanical features offer several advantages when it is used as native polymer or in composite materials. Structure and properties play a functional role in both the biofilm life cycle and biotechnological applications. Among all the cellulose-producing bacteria, acetic acid bacteria of the Komagataeibacter xylinus species play the most important role because they are considered the highest producers. Bacterial cellulose from acetic acid bacteria is widely investigated as native and modified biopolymer in functionalized materials, as well as in terms of differences arising from the static or submerged production system. In this paper, the huge amount of knowledge on basic and applied aspects of bacterial cellulose is reviewed to the aim to provide a comprehensive viewpoint on the intriguing interplay between the biological machinery of synthesis, the native structure, and the factors determining its nanostructure and applications. Since in acetic acid bacteria biofilm and cellulose production are two main phenotypes with industrial impact, new insights into biofilm production are provided.

Oxidative fermentations and exopolysaccharides production by acetic acid bacteria: a mini review.

Acetic acid bacteria are versatile organisms converting a number of carbon sources into biomolecules of industrial interest. Such properties, together with the need to limit chemical syntheses in favor of more sustainable biological processes, make acetic acid bacteria appropriate organisms for food, chemical, medical, pharmaceutical and engineering applications. At current, well-established bioprocesses by acetic acid bacteria are those derived from the oxidative pathways that lead to organic acids, ketones and sugar derivates. Whereas emerging applications include biopolymers, such as bacterial cellulose and fructans, which are getting an increasing interest for the biotechnological industry. However, considering the industrial demand of high performing bioprocesses, the production yield of metabolites obtained by acetic acid bacteria, is still not satisfying. In this paper we review the major acetic acid bacteria industrial applications, considering the current status of bioprocesses. We will also describe new biotechnological advances in order to optimize the industrial production, offering also an overview on future directions.

X-ray microtomography observations of xylem embolism in stems of Laurus nobilis are consistent with hydraulic measurements of percentage loss of conductance.

Drought-induced xylem embolism is a serious threat to plant survival under future climate scenarios. Hence, accurate quantification of species-specific vulnerability to xylem embolism is a key to predict the impact of climate change on vegetation. Low-cost hydraulic measurements of embolism rate have been suggested to be prone to artefacts, thus requiring validation by direct visualization of the functional status of xylem conduits using nondestructive imaging techniques, such as X-ray microtomography (microCT). We measured the percentage loss of conductance (PLC) of excised stems of Laurus nobilis (laurel) dehydrated to different xylem pressures, and compared results with direct observation of gas-filled vs water-filled conduits at a synchrotron-based microCT facility using a phase contrast imaging modality. Theoretical PLC calculated on the basis of microCT observations in stems of laurel dehydrated to different xylem pressures overall were in agreement with hydraulic measurements, revealing that this species suffers a 50% loss of xylem hydraulic conductance at xylem pressures averaging -3.5 MPa. Our data support the validity of estimates of xylem vulnerability to embolism based on classical hydraulic techniques. We discuss possible causes of discrepancies between data gathered in this study and those of recent independent reports on laurel hydraulics.

Color-Tunable Heterodinuclear Pt(II)/B(III) and Pt(II)/Ir(III) Arrays with N

The synthesis and photophysical properties of two multichromophoric systems, Pt(II)/B(III) and Pt(II)/Ir(III), based on novel N^O-julolidine ligands are reported. The functionalization of the julolidine core enables the introduction of two different anchoring sites, a terminal acetylene and an N^O chelating moiety, which allow the assembling of two different chromophoric centers. The complex photophysical behavior of these multicomponent arrays is rationalized by investigating a series of model compounds, which are prepared through specific synthetic pathways. The photophysical properties of the final multicomponent arrays are investigated in parallel with the models. The multichromophoric system, composed by a platinum(II) and an iridium(III) chromophore connected through a modified julolidine ditopic ligand, displays a peculiar excitation wavelength dependent luminescence behavior. It exhibits tuning of the emission color from blue to orange, passing through pure and warm white.

Increased production of bacterial cellulose as starting point for scaled-up applications.

Bacterial cellulose is composed of an ultrafine nanofiber network and well-ordered structure; therefore, it offers several advantages when used as native polymer or in composite systems.In this study, a pool of 34 acetic acid bacteria strains belonging to Komagataeibacter xylinus were screened for their ability to produce bacterial cellulose. Bacterial cellulose layers of different thickness were observed for all the culture strains. A high-producing strain, which secreted more than 23 g/L of bacterial cellulose on the isolation broth during 10 days of static cultivation, was selected and tested in optimized culture conditions. In static conditions, the increase of cellulose yield and the reduction of by-products such as gluconic acid were observed. Dried bacterial cellulose obtained in the optimized broth was characterized to determine its microstructural, thermal, and mechanical properties. All the findings of this study support the use of bacterial cellulose produced by the selected strain for biomedical and food applications.

The contribution of vascular and extra-vascular water pathways to drought-induced decline of leaf hydraulic conductance.

Drought stress can impair leaf hydraulic conductance (Kleaf), but the relative contribution of changes in the efficiency of the vein xylem water pathway and in the mesophyll route outside the xylem in driving the decline of Kleaf is still debated. We report direct measurements of dehydration-induced changes in the hydraulic resistance (R=1/K) of whole leaf (Rleaf), as well as of the leaf xylem (Rx) and extra-vascular pathways (Rox) in four Angiosperm species. Rleaf, Rx, and Rox were measured using the vacuum chamber method (VCM). Rleaf values during progressive leaf dehydration were also validated with measurements performed using the rehydration kinetic method (RKM). We analysed correlations between changes in Rx or Rox and Rleaf, as well as between morpho-anatomical traits (including dehydration-induced leaf shrinkage), vulnerability to embolism, and leaf water relation parameters. Measurements revealed that the relative contribution of vascular and extra-vascular hydraulic properties in driving Kleaf decline during dehydration is species-specific. Whilst in two study species the progressive impairment of both vascular and extra-vascular pathways contributed to leaf hydraulic vulnerability, in the other two species the vascular pathway remained substantially unaltered during leaf dehydration, and Kleaf decline was apparently caused only by changes in the hydraulic properties of the extra-vascular compartment.

Alkaline Earth Metal Ion/Dihydroxy-Terephthalate MOFs: Structural Diversity and Unusual Luminescent Properties.

Alkaline earth (group 2) metal ion organic frameworks (AEMOFs) represent an important subcategory of MOFs with interesting structures and physical properties. Five MOFs, namely, [Mg2(H2dhtp)2(µ-H2O)(NMP)4] (AEMOF-2), [Mg2(H2dhtp)1.5(DMAc)4]Cl·DMAc (AEMOF-3), [Ca(H2dhtp)(DMAc)2] (AEMOF-4), [Sr3(H2dhtp)3(DMAc)6]·H2O (AEMOF-5), and [Ba(H2dhtp)(DMAc)] (AEMOF-6) (H4dhtp = 2,5-dihydroxy-terepthalic acid; DMAc = N,N-dimethylacetamide; NMP = N-methylpyrrolidone), are presented herein. The reported MOFs display structural variety with diverse topologies and new structural features. Interestingly, AEMOF-6 is the first example of a Ba(2+)-H2dhtp(2-) MOF, and AEMOF-5 is only the second known Sr(2+)-H2dhtp(2-) MOF. Detailed photoluminescence studies revealed alkaline earth metal ion-dependent fluorescence properties of the materials, with the heavier alkaline earth metal ions exhibiting red-shifted emission with respect to the lighter ions at room temperature. A bathochromic shift of the emission was observed for the MOFs (mostly for AEMOF-3 and AEMOF-4) at 77 K as a result of excited state proton transfer (ESIPT), which involves an intramolecular proton transfer from a hydroxyl to an adjacent carboxylic group of the H2dhtp(2-) ligand. Remarkably, AEMOF-6 displays rare yellow fluorescence at room temperature, which is attractive for solid state lighting applications. To probe whether the alkaline earth metal ions are responsible for the unusual luminescence properties of the reported MOFs, the potential energy surfaces (PESs) of the ground, S0, and lowest energy excited singlet, S1, states of model complexes along the intramolecular proton transfer coordinate were calculated by DFT and TD-DFT methods.

Relax and refill: xylem rehydration prior to hydraulic measurements favours embolism repair in stems and generates artificially low PLC values.

Diurnal changes in percentage loss of hydraulic conductivity (PLC), with recorded values being higher at midday than on the following morning, have been interpreted as evidence for the occurrence of cycles of xylem conduits' embolism and repair. Recent reports have suggested that diurnal PLC changes might arise as a consequence of an experimental artefact, that is, air entry into xylem conduits upon cutting stems, even if under water, while under substantial tension generated by transpiration. Rehydration procedures prior to hydraulic measurements have been recommended to avoid this artefact. In the present study, we show that xylem rehydration prior to hydraulic measurements might favour xylem refilling and embolism repair, thus leading to PLC values erroneously lower than those actually experienced by transpiring plants. When xylem tension relaxation procedures were performed on stems where refilling mechanisms had been previously inhibited by mechanical (girdling) or chemical (orthovanadate) treatment, PLC values measured in stems cut under native tension were the same as those measured after sample rehydration/relaxation. Our data call for renewed attention to the procedures of sample collection in the field and transport to the laboratory, and suggest that girdling might be a recommendable treatment prior to sample collection for PLC measurements.

Tuning excited states of bipyridyl platinum(II) chromophores with π-bonded catecholate organometallic ligands: synthesis, structures, TD-DFT calculations, and photophysical properties.

A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n (2-5) (LM = Cp*Rh(cat), n = 2; Cp*Ir(cat), n = 2; Cp*Ru(cat), n = 1; and (C6H6)Ru(cat), n = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)Pt(II) complexes 2 and 3 with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates 4 and 5 showed the presence of Pt···Pt and π-π interactions among individual units and generated one- and two-dimensional supramolecular chains. The photophysical properties of these compounds 2-5 were investigated and showed that all compounds are luminescent at low temperature, in contrast to the well-known parent compound [(C6H4O2)Pt(bpy)] (1), which is weakly luminescent at 77 K. Time-dependent density functional theory studies are advanced to explain this difference in behavior and to highlight the role of the π-bonded catecholate system.

Multichromophoric arrays arranged around a triptycene scaffold: synthesis and photophysics.

Here we report on the synthesis, characterization, and photophysics of multichromophoric arrays based on a triptycene scaffold that acts as a bridging ligand for Ir(III) and Os(II) satellite active components. The triptycene scaffold not only furnishes a rigid star-shaped 3D displacement of the metallic units in space but also plays an active role in the energy cascade. The transition metal complexes have been designed in order to display an ideal cascade in their lowest excited state energy levels. For this purpose, a novel Ir(III) complex containing two dbpz (dibenzo[a,c]phenazine) ligands (Ir) has been synthesized. The key step in the synthesis of the array was the final cross-coupling between the mixed complex IrF-Os and Ir, providing the target heterotrinuclear complex IrF-Ir-Os. The photophysical properties of models confirmed the appropriate energy displacement of the single chosen active units, in the order triptycene > IrF > Ir > Os, and fast and efficient energy transfer processes leading to the final population of the Os-based triplet level have been evidenced. The reported arrays can be considered as efficient antenna systems with an absorption range extending up to 700 nm, where the triptycene bridging ligand provides both a structural and a photophysical function.

Acetic Acid bacteria: physiology and carbon sources oxidation.

Acetic acid bacteria (AAB) are obligately aerobic bacteria within the family Acetobacteraceae, widespread in sugary, acidic and alcoholic niches. They are known for their ability to partially oxidise a variety of carbohydrates and to release the corresponding metabolites (aldehydes, ketones and organic acids) into the media. Since a long time they are used to perform specific oxidation reactions through processes called "oxidative fermentations", especially in vinegar production. In the last decades physiology of AAB have been widely studied because of their role in food production, where they act as beneficial or spoiling organisms, and in biotechnological industry, where their oxidation machinery is exploited to produce a number of compounds such as l-ascorbic acid, dihydroxyacetone, gluconic acid and cellulose. The present review aims to provide an overview of AAB physiology focusing carbon sources oxidation and main products of their metabolism.

A Microbial Co-Culturing System for Producing Cellulose-Hyaluronic Acid Composites.

In this study, a co-culture system combining bacterial cellulose (BC) producers and hyaluronic acid (HA) producers was developed for four different combinations. AAB of the genus Komagataeibacter sp. and LAB of the Lactocaseibacillus genus were used to produce BC and HA, respectively. Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction were used to investigate changes in BC-HA composites chemical and morphological structure. Water absorption, uptake, and antibacterial properties were also tested. Outcomes highlighted a higher bacterial cellulose yield and the incorporation of hyaluronic acid into the composite. The presence of hyaluronic acid increased fiber dimension-nearly doubled for some combinations-which led to a decreased crystallinity of the composites. Different results were observed based on the BC producer and HA producer combination. However, water holding capacity (WHC) in all the samples improved with the presence of HA, while water uptake worsened. A thymol-enriched BC-HA composite showed high antibacterial activity against Escherichia coli DSM 30083T and Staphylococcus aureus DSM 20231T. Results could contribute to opening new applications in the cosmetics or pharmaceutical fields.

Clinical and economic comparative analysis of laparotomy versus laparoscopy in the first gastric bypass surgeries in a bariatric and metabolic surgery service in a city in southern Brazil.

INTRODUCTION: this paper aims to evaluate the main direct and indirect costs of the first laparotomies and laparoscopies in bariatric surgeries with a clinical-economical retrospective and cross-sectional analysis from 2017 to 2020 at a hospital with specialties besides the basic ones in southern Brazil. METHODS: the study sample included 26 participants. The first 13 laparotomies, and the first 13 laparoscopies performed at the bariatric surgery service of the institution were evaluated. The values evaluated in such comparison analyzed the costs of operation and hospitalization. It is important to highlight that, in addition to the cost benefit, other costs take significance in the health area, such as: cost-utility, cost-effectiveness and cost-minimization, in addition to the cost-opportunity that is reassessed in the observation of the broad context associating all the values raised here. The software used for data analysis was Excel version® 365. The economic analysis was performed evidencing the profile of the patients and the direct and indirect costs involved in each segmentation. RESULTS: the direct and indirect costs of videolaparoscopy amounted to BRL 10,108.10 and laparoscopy to the amount of BRL 12,568.14. CONCLUSION: it was concluded that laparoscopy presents more savings in the aspects of all health valuations to the detriment of laparotomy. It was concluded that the videolaparoscopy presents more savings in the aspects of all health valuations than the laparotomy.