Bacterial Fermentation Process Research Articles

Screening and Optimization of α-Glucosidase Inhibitor Production by Potent Strain of Bacillus subtilis Isolated from Peruyaan, Fermented Soy-Food of Northeast India

Background. Fermented soy foods exhibit the capability to inhibit the α-glucosidase enzyme. The bacteria isolated from these fermented soy foods may contribute to the production of a higher quantity of α-glucosidase inhibitor (α-GI) in optimized condition. Aim. The present study aims to isolate α-glucosidase inhibitor producing bacterial strain from peruyaan, a traditional fermented soy food of Arunachal Pradesh, optimize the production of α-GI for maximum yield, and assess the compounds. Result. Bacillus subtilis PM NEIST_4 (identified by 16S rRNA gene sequencing) was isolated as a potential strain that exhibit maximum α-glucosidase inhibition. This strain showed maximum α-GI productivity in Mueller Hinton Broth (MHB). The cultivation parameters for fermentation of MHB were optimized in order to maximize the yield of α-GIs. The α-GI productivity of 1616.613 ± 84.54 U/mL was observed before optimization, which increased by almost three times after optimization (4808.324 ± 13 U/mL). In vitro assays against α-glucosidase enzyme revealed a significant IC50 value of 596.532 ± 44.80 μg/mL after the optimized study compared to that before optimization (IC50 1705.617 ± 43.95 ug/mL). Besides, α-glucosidase enzyme inhibitory property of fermented MHB (FMHB) was found to be unaffected at varied range of pH and temperature. Oral gavaging of FMHB in sucrose-loaded Wistar rat exhibited maximum reduction in postprandial blood glucose at 400 mg/kg body weight. Furthermore, FMHB was fractionated using solvents of increasing polarity including n-hexane, ethyl acetate, and n-butanol. Ethyl acetate fraction that exhibited the strongest inhibitory action against the α-glucosidase enzyme (IC50 value of 251.55 ± 19.65 μg/mL), showed the presence of pyrrolopyrazine derivatives through GC-MS and LC-MS analyses. Conclusion. The present study demonstrated the isolation of a potent α-GI producing bacterial strain from traditional fermented soy food, and the optimization of the bacterial fermentation process was achieved to maximize the yield of α-GI. These findings underscore promising industrial potential of B. subtilis PM NEIST_4, advocating the use of indigenous microbial resources for the production of α-GI.

Production optimization of antifungal lipopeptides by Bacillus subtilis CtpxS2-1 using low-cost optimized medium

The aim of the present study was evaluated the use of low-cost optimized medium defatted soy flour and molasses (DSF40–MOL5; 40 g l−1 defatted soy flour, 5 g l−1 molasses plus mineral trace supplements) to improvement the antifungal lipopeptides production by biocontrol agent Bacillus subtilis CtpxS2-1. First, population dynamics of CtpxS2-1 in DSF40–MOL5 medium was recorded in a 5-l fermenter during 24 h, 48 h and 72 h and compared with the bacterium grown in medium optimal for lipopeptide production (MOLP) as control. Results showed that the CtpxS2-1 population dynamics, pH and oxygen consumption was similar in both media with a 4–h lag phase, followed by exponential growth and maximum production around 9.5 log CFU ml−1 after 16–18 h. Second, lipopeptides extracts quantifications, followed of high-performance thin layer chromatographic (HPTLC) and bioautography analysis against Colletotrichum acutatum showed a significant increment of fengycin and iturin lipopeptides production and their antifungal activity in DSF40–MOL5 compared with MOLP. PCR (RT-PCR)/RT q-PCR analysis during production confirmed the transcription of fengycin, iturin an surfactin lipopeptides by amplification of cDNA; and that FenB and ItuA genes were progressive expressed in higher amounts throughout in DSF40–MOL5 than MOLP. The biosynthesis of FenB gene and its antifungal activity against C. acutatum was the highest for CtpxS2-1 grown in DSF40–MOL5. Surfactin genes were also expressed during production process however their didn’t showed antifungal activity Finally, treatment of artificially infected seed of three cultivars of Lupinus mutabilis with CtpxS2-1 grown in DSF40-MOL5 reduced anthracnose up to 0% and improved seed and plant health. This evidence supports that antifungal potential of B.subtilis CtpxS2-1 to control lupin anthracnose could be enhanced using low-cost medium DSF40–MOL5 and it could provide a reliable method for scaling up the bacterial fermentation process at industrial level.

Skrining Novel Prebiotik Selective Fermentation Initiator (SFI) Untuk Bakteri Probiotik Elektrogenik Kulit

The ability of electrogenic bacteria to generate electricity has been widely reported. In some cases of bacteria, the electricity production comes from the bacterial fermentation process of SFI compounds by these bacteria. Later, the resulted electrons are transferred out from inside to extracellular recipient molecules. Among of these studies has shown the ability of gram-positive bacteria S. epidermidis ATCC 12228 in terms of SFI compounds utilization to increase bacterial electron production and its application in the medical field. Based on these studies, the discovery of new SFI compounds becomes interesting to be explored. In this study, a new SFI compound was screened from 24 different compounds. The screen was initiated by testing the ability of these compounds to increase the fermentation activity of S. epidermidis ATCC 12228 in a 96-well plate. Determination of SFI compound was carried out by checking the exclusivity of the compound to increase the fermentation activity of S. epidermidis ATCC 12228. The selected SFI compound was then tested for cytotoxicity against this bacterium and its ability to increase the electron production of S. epidermidis ATCC 12228 using a microbial fuel cell (MCF). This study was successfully demonstrated the non-toxic properties of p-coumaric acid, also the ability of this compound to increase the fermentation activity and electron production of S. epidermidis ATCC 12228. This research is expected to be the first step to find another novel SFI compounds that will be useful in certain fields in the future.

Postbiotics as Dynamic Biological Molecules for Antimicrobial Activity: A Mini-Review

Postbiotics, products, or metabolites secreted by living probiotic bacteria like teichoic acids, peptides, enzymes, peptidoglycans, polysaccharides, organic acids, and external cell proteins are said to be produced during the bacterial fermentation process. However, postbiotics may provide immunization, antioxidant, prevents inflammation, low cholesterolemic, antimicrobial, antagonistic obesity, contrast hypertensive, and diabetic retinopathy impacts. In the current review, we attempt to display the antimicrobial performance of postbiotics. In this regard, we considered microbial strains used as postbiotic sources and postbiotics as antimicrobial agents in food products. All databases such as Science Direct, Scopus, Pub Med, and Google Scholar were examined using the following keywords: “postbiotics”, “Antimicrobial activity”, “Anti-inflammatory”, and “Low cholesterolemic”. Further studies demonstrated that probiotics are fed special forms of fiber (prebiotic) molecules, indicating substances known as postbiotics. Furthermore, short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate are among the comprehensively investigated postbiotics. The extraction and purification of these compounds are carried out by means of dialysis, centrifugation, and freeze-drying techniques. According to the gained results, postbiotics assist in improving host health by increasing certain physiological functions. Furthermore, postbiotics can be used to increment the useful lifetime of different foods, like dairy products. It has also been shown that manually adding postbiotics to such products prevents the growth and proliferation of molds and thus the spoilage caused by them. This inhibitory effect indicates the antimicrobial properties of these compounds. Finally, we will see significant advances in the biological preservation of products, especially in the food industry.

A Novel Double Mosaic Virus-like Particle-Based Vaccine against SARS-CoV-2 Incorporates Both Receptor Binding Motif (RBM) and Fusion Domain.

COVID-19 has emerged, and has rapidly become a major health problem worldwide, causing millions of mortalities. Vaccination against COVID-19 is the most efficient way to stop the pandemic. The goal of vaccines is to induce neutralizing antibodies against SARS-CoV-2 virus. Here, we present a novel double mosaic virus-like particle (VLP) displaying two independent neutralizing epitopes, namely the receptor binding motif (RBM) located in S1 and the fusion peptide (AA 817–855) located in S2. CuMVTT virus-like particles were used as VLP scaffold and both domains were genetically fused in the middle of CuMVTT subunits, which co-assembled into double mosaic particles (CuMVTT-DF). A single fusion mosaic particle (CuMVTT-FP) containing the fusion peptide only was used for comparison. The vaccines were produced in E. coli, and electron microscopy and dynamic light scattering confirmed their integrity and homogeneity. In addition, the CuMVTT-DF vaccine was well recognized by ACE2 receptor, indicating that the RBM was in native conformation. Both CuMVTT-FP and CuMVTT-DF vaccines induced high levels of high avidity IgG antibodies as well as IgA recognizing spike and RBD in the case of CuMVTT-DF. Both vaccine candidates induced virus-neutralizing antibodies indicating that the fusion peptide can independently induce virus-neutralizing antibodies. In contrast, CuMVTT-DF containing both RBM and fusion peptide induced a higher level of neutralizing antibodies suggesting that the new double mosaic vaccine candidate CuMVTT-DF consisting of two antigens in one VLP maybe an attractive candidate for scale-up in a bacterial fermentation process for clinical development.

Recyclable Polyhydroxyalkanoates via a Regioselective Ring-Opening Polymerization of α,β-Disubstituted β-Lactone Monomers

The economical and societal issues associated with the depletion of fossil feedstocks and severe accumulation of nondegradable plastics in nature have pushed the increasing efforts toward the development of biodegradable polymers with unique recyclability. The bacterial polyhydroxyalkanoates (PHAs) represent a unique class of biodegradable polymers that have found a variety of applications in packaging, agricultural, biomedical, and pharmaceutical fields. Due to the high production costs and limited volumes for the bacterial fermentation process, the chemical synthesis of PHAs via ring-opening polymerization of lactone monomers has attracted intensive attention. However, most β-lactones feature a substituent group at the β-position, and they cannot be recycled back into the monomers or other intermediates in quantitative yields. Rare examples were reported regarding the synthesis of PHAs based on β-lactones with α,β-disubstituted groups or a ring fusion at both α- and β-positions. Here, we report a type of β-lactone fused with a five-membered ring fusion at α- and β-positions (cis-6-oxabicyclo[3.2.0]heptan-7-one, β-CPL), from the ring-expansive carbonylation of cyclopentene oxide (CPO). With the efficient catalysts, the ring-opening polymerization of β-CPL under ambient conditions produces a novel type of polyhydroxyalkanoates with controlled linear and/or cyclic topologies; the produced PHAs feature a high melting temperature (∼185 °C) and high molecular weight (Mn = 1.01 × 105 g mol–1, Đ = 1.36) via a regioselective fashion through an O-acyl cleavage. In particular, the quantitative formation of α,β-unsaturated carboxylic acid during pyrolysis represents a rare example that the recyclability can be accomplished via a transformation of α,β-unsaturated carboxylic acid to β-lactone monomers.

Bacterial fabric: introductory studies on the application of biomimetics in the bacterial fermentation process

Thinking about innovations that reduce environmental impact and offer quality consumer goods is a way of proposing a future scenario governed by eco-efficiency values. Through an exploratory bibliographic and documentary research, which qualitatively analyses Kombucha authors and fermenters, this article seeks to identify the relationship between biomimetics and bacterial fabric production as an eco-efficient product in the fashion market chain. The general objective of this case study is to explain the fermentation process to encourage the search for raw materials inserted in the sustainability proposal.

On-line analysis and in situ pH monitoring of mixed acid fermentation by Escherichia coli using combined FTIR and Raman techniques

We introduce an experimental setup allowing continuous monitoring of bacterial fermentation processes by simultaneous optical density (OD) measurements, long-path FTIR headspace monitoring of CO2, acetaldehyde and ethanol, and liquid Raman spectroscopy of acetate, formate, and phosphate anions, without sampling. We discuss which spectral features are best suited for detection, and how to obtain partial pressures and concentrations by integrations and least squares fitting of spectral features. Noise equivalent detection limits are about 2.6 mM for acetate and 3.6 mM for formate at 5 min integration time, improving to 0.75 mM for acetate and 1.0 mM for formate at 1 h integration. The analytical range extends to at least 1 M with a standard deviation of percentage error of about 8%. The measurement of the anions of the phosphate buffer allows the spectroscopic, in situ determination of the pH of the bacterial suspension via a modified Henderson-Hasselbalch equation in the 6–8 pH range with an accuracy better than 0.1. The 4 m White cell FTIR measurements provide noise equivalent detection limits of 0.21 μbar for acetaldehyde and 0.26 μbar for ethanol in the gas phase, corresponding to 3.2 μM acetaldehyde and 22 μM ethanol in solution, using Henry’s law. The analytical dynamic range exceeds 1 mbar ethanol corresponding to 85 mM in solution. As an application example, the mixed acid fermentation of Escherichia coli is studied. The production of CO2, ethanol, acetaldehyde, acids such as formate and acetate, and the changes in pH are discussed in the context of the mixed acid fermentation pathways. Formate decomposition into CO2 and H2 is found to be governed by a zeroth-order kinetic rate law, showing that adding exogenous formate to a bioreactor with E. coli is expected to have no beneficial effect on the rate of formate decomposition and biohydrogen production.

Biotransformation of bovine tannery fleshing into utilizable product with multifunctionalities

Leather industries aim at the transformation of putrescible animal raw hides and skins into a stable non-putrescible material (leather), ultimately resulting in solid wastes generation. Storage of limed bovine fleshing, a predominant proteinaceous solid waste material from pre-tanning processes is highly discouraged due to their putrescible nature. Diversely, bio-conversion of solid waste into a saleable product could be achieved by bacterial fermentation process. Lactic acid (LA) fermentation with Delimed Bovine Tannery Fleshing (DBTF) by Lactobacillus plantarum was experimented; incubation time, tapioca flour and lactose were the three prime independent variables studied. Maximum LA production in steam cooked DBTF medium was achieved with pH 6; inoculum 12.5% (v/w); lactose 8.81% (w/w) and tapioca flour 8.9% (w/w) at 96 hours of fermentation. Initial yield of about 4.56 g/L of LA (p < .05), upon statistical manipulation of the medium composition marked up to 12.36 g/L, enabling 2.7-fold increase in the LA production with DBTF as a relatively cut-rate substrate. Fermentation resulted in Fermented Fleshing Flour (FFF) with marked protein level of 76.32% and lower fibre content. Formation of protein hydrolysates and new acid groups in FFF were authenticated via Field Emission Scanning Electron Microscopic (FE-SEM) and Fourier Transform Infra-red Spectroscopic (FTIR) analyses respectively. In situ acid (LA) generation and formation of protein hydrolysates/free amino acids during LA fermentation points to the antibacterial (against Gram-negative bacteria, followed by Gram-positive bacteria) and in vitro antioxidative properties with dose dependency, of FFF, favouring its possible utilization in aqua feed industries as a superior grade proteinaceous feed ingredient with inbuilt bio-functionalities.”

Industrial Production of Poly-β-hydroxybutyrate from CO2: Can Cyanobacteria Meet this Challenge?

The increasing impact of plastic materials on the environment is a growing global concern. In regards to this circumstance, it is a major challenge to find new sources for the production of bioplastics. Poly-β-hydroxybutyrate (PHB) is characterized by interesting features that draw attention for research and commercial ventures. Indeed, PHB is eco-friendly, biodegradable, and biocompatible. Bacterial fermentation processes are a known route to produce PHB. However, the production of PHB through the chemoheterotrophic bacterial system is very expensive due to the high costs of the carbon source for the growth of the organism. On the contrary, the production of PHB through the photoautotrophic cyanobacterium system is considered an attractive alternative for a low-cost PHB production because of the inexpensive feedstock (CO2 and light). This paper regards the evaluation of four independent strategies to improve the PHB production by cyanobacteria: (i) the design of the medium; (ii) the genetic engineering to improve the PHB accumulation; (iii) the development of robust models as a tool to identify the bottleneck(s) of the PHB production to maximize the production; and (iv) the continuous operation mode in a photobioreactor for PHB production. The synergic effect of these strategies could address the design of the optimal PHB production process by cyanobacteria. A further limitation for the commercial production of PHB via the biotechnological route are the high costs related to the recovery of PHB granules. Therefore, a further challenge is to select a low-cost and environmentally friendly process to recover PHB from cyanobacteria.

Acetone–butanol–ethanol fermentation from sugarcane bagasse hydrolysates: Utilization of C5 and C6 sugars

Abstract Background Fuels and chemicals from renewable feedstocks have a growing demand, and acetone, butanol and ethanol (ABE) are some relevant examples. These molecules can be produced by the bacterial fermentation process using hydrolysates generated from lignocellulosic biomass as sugarcane bagasse, one of the most abundant sources of lignocellulosic biomass in Brazil. It originates as a residue in mills and distilleries in the production of sugar and ethanol. Results In the present work, two strategies to generate hydrolysates of sugarcane bagasse were adopted. The fermentation of the first hydrolysate by Clostridium acetobutylicum DSM 6228 resulted in final concentrations of butanol, acetone and ethanol of 6.4, 4.5 and 0.6 g/L, respectively. On the other hand, the second hydrolysate presented better results (averages of 9.1, 5.5 and 0.8 g/L, respectively), even without the need for nutrient supplementation, since key elements were already present in the medium. The productivity (QP) and yield (YP/S) of the solvents with second hydrolysate were 0.5 g/L·h-1 and 0.4 g/g, respectively. Conclusions The results described herein open new perspectives for the production of important molecules from residual lignocellulosic biomass for the fuel and chemical industries within the context of second-generation biorefinery. How to cite: Gomes AC, Rodrigues MI, Passos DF, et al. Acetone-butanol-ethanol fermentation from sugarcane bagasse hydrolysates: utilization of C5 and C6 sugars. Electron J Biotechnol 2019;42. https://doi.org/10.1016/j.ejbt.2019.10.004 .

Dynamics of Bacterial Community and Fermentation Quality during Ensiling of Wilted and Unwilted Moringa oleifera Leaf Silage with or without Lactic Acid Bacterial Inoculants.

To investigate the effects of wilting and lactic acid bacterial inoculants on the fermentation quality and bacterial community of Moringa oleifera leaf silage, fresh and wilted M. oleifera leaves were ensiled with or without Lactobacillus farciminis LF or Lactococcus lactis LL for 1, 7, 14, 30, and 60 days. The results showed that wilting, inoculants, and their interaction exerted significant (P < 0.05) effects on the fermentation characteristics covering dry matter loss, pH value, lactic acid bacterial number, the ratio of lactic acid to acetic acid, and the relative abundances of bacteria, like for species of Lactobacillus, Lactococcus, Pediococcus, Enterococcus, Leuconostoc, and Enterobacter Both LF and LL improved the fermentation quality of wilted and unwilted M. oleifera leaf silage by accelerating lactic acid production and pH decline, decreasing dry matter loss, and inhibiting yeast and coliform bacterial growth through the whole fermentation process. During ensiling, the abundances of Lactococcus, Enterococcus, and Leuconostoc spp. increased from day 1 to day 7 and then declined sharply from day 7 to day 14. Members of these genera and Enterobacter were inhibited, whereas Lactobacillus spp. were enhanced by these two lactic acid bacterial inoculants. The relative abundances of Enterobacter, Enterococcus, and Pediococcus spp. in inoculated silages were relatively low during the whole ensiling process. A lower abundance of Enterobacter spp. was observed in wilted silages than in unwilted silages. In summary, wilting and lactic acid bacterial inoculants had an influence on bacterial community and the fermentation process; LF and LL improved the fermentation quality of wilted and unwilted M. oleifera leaf silage.IMPORTANCEMoringa oleifera leaf is a high-quality feed source for livestock and is increasingly used all over the world. Ensiling might be an effective method for preservation of the leaves. In the practice of silage making, lactic acid bacterial inoculants and wilting are commonly used to improve nutrition preservation. Monitoring the changes in a bacterial community during fermentation gives an insight into understanding and improving the ensiling process. Our results suggest that wilting and lactic acid bacterial inoculants had an influence on the bacterial community and fermentation process of M. oleifera leaf silage. Wilting showed positive effects on silage fermentation by decreasing the abundance of Enterobacter spp., while LF and LL improved the fermentation quality by inhibiting Enterobacter spp. and enhancing Lactobacillus spp. Both LF and LL accelerated the ensiling process from cocci (like Lactococcus, Enterococcus, and Leuconostoc spp.) to lactobacilli.

Low FODMAP diet in children and adolescents with functional bowel disorder: A clinical case note review.

Background and AimsFunctional bowel disorders (FBD), such as irritable bowel syndrome (IBS), are increasingly more common in children and affect up to 20% of children. The etiology is multifactorial with no clear organic cause. Symptoms are recurrent and are associated with a reduced quality of life, school absences, and psychological challenges. Treatment options are variable. FODMAPs are short‐chained carbohydrates, poorly absorbed by the gastrointestinal tract due to their increased osmotic activity and excess gas production from the bacterial fermentation process. There is a paucity of data examining dietary interventions that restrict carbohydrates in children with IBS. The aim of this study was to examine the use of the low FODMAP diet (LFD) in children with an FBD.MethodsA retrospective clinical case note review of children with an FBD managed with an LFD was undertaken. Anthropometry and clinical data were collected by a pediatric gastroenterology dietitian. An IBS satisfaction survey was used to assess diet outcomes. Statistical analyses were completed using Excel.ResultsOf the 29 children included in this study, complete resolution of gastrointestinal symptoms was observed for 11 of 12 (92%) of those with bloating, 13 of 15 (87%) of those with diarrhea, and 17 of 22 (77%) of those with abdominal pain. Twenty‐three (79%) participants reported an improvement of symptoms. Fructans were the most common symptom‐causing carbohydrate.ConclusionThe LFD is a useful dietary treatment strategy for children with FBD. This study adds to the small body of evidence supporting FODMAP dietary interventions in children with FBD. Further prospective studies are required.

Exploiting Hydrogenophaga pseudoflava for aerobic syngas-based production of chemicals

Gasification is a suitable technology to generate energy-rich synthesis gas (syngas) from biomass or waste streams, which can be utilized in bacterial fermentation processes for the production of chemicals and fuels. Established microbial processes currently rely on acetogenic bacteria which perform an energetically inefficient anaerobic CO oxidation and acetogenesis potentially hampering the biosynthesis of complex and ATP-intensive products. Since aerobic oxidation of CO is energetically more favorable, we exploit in this study the Gram-negative β-proteobacterium Hydrogenophaga pseudoflava DSM1084 as novel host for the production of chemicals from syngas. We sequenced and annotated the genome of H. pseudoflava and established a genetic engineering toolbox, which allows markerless chromosomal modification via the pk19mobsacB system and heterologous gene expression on pBBRMCS2-based plasmids. The toolbox was extended by identifying strong endogenous promotors such as PgapA2 which proved to yield high expression under heterotrophic and autotrophic conditions. H. pseudoflava showed relatively fast heterotrophic growth in complex and minimal medium with sugars and organic acids which allows convenient handling in lab routines. In autotrophic bioreactor cultivations with syngas, H. pseudoflava exhibited a growth rate of 0.06 h−1 and biomass specific uptakes rates of 14.2 ± 0.3 mmol H2 gCDW−1 h−1, 73.9 ± 1.8 mmol CO gCDW−1 h−1, and 31.4 ± 0.3 mmol O2 gCDW−1 h−1. As proof of concept, we engineered the carboxydotrophic bacterium for the aerobic production of the C15 sesquiterpene (E)-α-bisabolene from the C1 carbon source syngas by heterologous expression of the (E)-α-bisabolene synthase gene agBIS. The resulting strain H. pseudoflava (pOCEx1:agBIS) produced 59 ± 8 μg (E)-α-bisabolene L−1 with a volumetric productivity Qp of 1.2 ± 0.2 μg L−1 h−1 and a biomass-specific productivity qp of 13.1 ± 0.6 μg gCDW−1 h−1. The intrinsic properties and the genetic repertoire of H. pseudoflava make this carboxydotrophic bacterium a promising candidate for future aerobic production processes to synthesize more complex or ATP-intensive chemicals from syngas.

Influence of Drying Temperature on Tensile and Bursting Strength of Bacterial Cellulose Biofilm

The article presents an experimental study of mechanical properties of cellulose biofilm produced by bacterial fermentation process. Naturally derived biomaterial has great current and potential applications therefore the conditions of material preparation as well as control and prediction of mechanical properties is still a relevant issue. Bacterial cellulose was obtained as a secondary product from Kombucha drink. Presented technique for material preparation and drying is particularly simple and easy to access. The influence of drying temperature (25 °C, 50 °C and 75 °C) on the sample size (thickness and planar dimensions) and mechanical properties (tensile and bursting strength) of cellulose biofilm has been evaluated. It was estimated that during drying biofilm specimens lost up to 92 % of weight and up to 87 % of thickness therefore planar specimen dimensions varied insignificantly. The study showed that the drying temperature is important for optimum strength properties of bacterial cellulose biofilm. The maximum tensile strength (27.91 MPa) was recorded for the samples dried at temperature of 25 °C, when the moisture from the biomaterial is removed gradually and good deformation properties are ensured (respectively tensile extension 18.8 %). Under higher drying temperature biomaterial shows lower values of tensile strength and higher values of bursting strength. The maximum bursting strength (57.2 MPa) was recorded for samples dried at 75 °C when punch displacement changes were insignificant for all tested samples (from 17.8 mm to 21.7 mm). DOI: http://dx.doi.org/10.5755/j01.ms.25.3.20764

Bacterial fermentation and respiration processes are uncoupled in anoxic permeable sediments.

Permeable (sandy) sediments cover half of the continental margin and are major regulators of oceanic carbon cycling. The microbial communities within these highly dynamic sediments frequently shift between oxic and anoxic states, and hence are less stratified than those in cohesive (muddy) sediments. A major question is, therefore, how these communities maintain metabolism during oxic-anoxic transitions. Here, we show that molecular hydrogen (H2) accumulates in silicate sand sediments due to decoupling of bacterial fermentation and respiration processes following anoxia. In situ measurements show that H2 is 250-fold supersaturated in the water column overlying these sediments and has an isotopic composition consistent with fermentative production. Genome-resolved shotgun metagenomic profiling suggests that the sands harbour diverse and specialized microbial communities with a high abundance of [NiFe]-hydrogenase genes. Hydrogenase profiles predict that H2 is primarily produced by facultatively fermentative bacteria, including the dominant gammaproteobacterial family Woeseiaceae, and can be consumed by aerobic respiratory bacteria. Flow-through reactor and slurry experiments consistently demonstrate that H2 is rapidly produced by fermentation following anoxia, immediately consumed by aerobic respiration following reaeration and consumed by sulfate reduction only during prolonged anoxia. Hydrogenotrophic sulfur, nitrate and nitrite reducers were also detected, although contrary to previous hypotheses there was limited capacity for microalgal fermentation. In combination, these experiments confirm that fermentation dominates anoxic carbon mineralization in these permeable sediments and, in contrast to the case in cohesive sediments, is largely uncoupled from anaerobic respiration. Frequent changes in oxygen availability in these sediments may have selected for metabolically flexible bacteria while excluding strict anaerobes.

Environmental pollutant-mediated disruption of gut microbial metabolism of the prebiotic inulin

Exposure to environmental pollutants is associated with a greater risk for metabolic diseases including cardiovascular disease. Pollutant exposure can also alter gut microbial populations that may contribute to metabolic effects and progression of inflammatory diseases. Short-chain fatty acids (SCFAs), produced from gut fermentation of dietary carbohydrates, such as inulin, exert numerous effects on host energy metabolism and are linked to a reduced risk of diseases. The hypothesis was that exposure to dioxin-like pollutants modulate gut microbial viability and/or fermentation processes. An inulin-utilizing isolate was collected from murine feces, characterized and used in subsequent experiments. Exposure to polychlorinated biphenyl, PCB 126 impeded bacterial viability of the isolate at concentrations of 20 and 200 μM. PCB 126 exposure also resulted in a significant loss of intracellular potassium following exposure, indicating cell membrane disruption of the isolate. Furthermore, total fecal microbe samples from mice were harvested, resuspended and incubated for 24 h in anaerobic media containing inulin with or without PCB 126. HPLC analysis of supernatants revealed that PCB 126 exposure reduced succinic acid production, but increased propionate production, both of which can influence host glucose and lipid metabolism. Overall, the presented evidence supports the idea that pollutant exposure may contribute to alterations in host metabolism through gut microbiota-dependent mechanisms, specifically through bacterial fermentation processes or membrane disruption.

Model-Based Computation of Critical Operation Points in Biogas Producing Plants

Reducing the use of fossil fuels for energy production is one of the main objectives in 21st century. In order to achieve this target renewable energy resources (like agricultural waste) in biogas plants can be used. An anaerobic bacterial fermentation process digests the substrates into methane and carbon dioxide. The process itself has strong fluctuations in terms of net methane yield due to different amounts and composition of agricultural influents. For increasing the space time yield two main difficulties are encountered. The first one is system-specific and includes stirrer design and reactor geometry. The second affects the biotechnological fermentation process. The following work is focusing on the fermentation process. The determination of critical parameters for the optimization of the anaerobic microbial digestion is investigated. An economic approach for solving these problems is only feasible by using mathematical models and simulation. Consequently two fermentation models are compared by regarding parameter sensitivity and critical operational points. The first one is based on simple Monod-kinetics while the second one is extended with two steps of fermentation and therefore two different microbial consortia and additive inhibition effects. The complex model is able to describe different phenomena in more detail. But its estimability and therefore its validation is difficult without further investigation of the model structure and the reduction of the model complexity. One important result of the investigation is that stable process conditions with simultaneous high yields are depending on a careful adjustment of the loading rate and therefore requiring precise model parameters.

AKTIVITAS ANTIOKSIDAN METABOLIT SEKUNDER BAKTERI ENDOFIT AKAR TANAMAN Moringa oleifera L (Kelor)

[ANTIOXIDANT ACTIVITY OF SECONDARY METABOLITE FROM ENDOFIT BACTERIA OF Moringa oleifera L (KELOR) ROOTS] The purpose of this research was aims to isolate and measure the ability of antioxidant activity from secondary metabolites produced by endophytic bacteria that grow in the live tissue root of Moringa oleifera L. (kelor). Endophytic bacteria were purified and cultured using a solid Murashige-skoog (MS) medium for 3 days at room temperature. Secondary metabolites were obtained by centrifugation process at a rate of 3000 rpm for 20 minutes. The bacterial fermentation process using Nutrient Broth (NB) medium for 72 hours with a shaker speed at 170 rpm . The suspension supernatant was extracted with a maceration method using 86% ethyl acetate, followed by vacuum rotary evaporator concentration at 40 ° C. The extract antioxidant activity test was performed using the DPPH (1,1-diphenyl-2-picrylhydrazyl) method using a UV-Vis spectrophotometer at 517 nm wavelength and ascorbic acid as standard. The result of DPPH test showed that the antioxidant activity of ethyl acetate extract of endophytic bacterial from root of M. oleifera L root has IC50 value at 315, 396 ppm. Based on these results, it can be concluded that the secondary metabolite extract of endophytic bacterial from M. oleifera L root classified as weak antioxidant (IC50&gt; 250 ppm).

Special Nanoskin-ACT-Biological Membranes from Deep Wounds

Bacterial cellulose (BC) is established as a newest biomaterial, and it can be used for medical and odontology applications. In addition, it has called attention for uses such as membrane for wound care and tissue engineering. In this work, the bacterial cellulose fermentation process is modified by the addition of natural materials before the bacteria are inoculated. In vivo behavior using natural ECM for regenerative medicine is presented and completed wound healing process is 3 months.