scholarly journals Use of Cellulolytic Marine Bacteria for Enzymatic Pretreatment in Microalgal Biogas Production

2014 ◽  
Vol 80 (14) ◽  
pp. 4199-4206 ◽  
Author(s):  
Camilo Muñoz ◽  
Catalina Hidalgo ◽  
Manuel Zapata ◽  
David Jeison ◽  
Carlos Riquelme ◽  
...  
Keyword(s):  
Biogas Production ◽  
Botryococcus Braunii ◽  
Aeromonas Salmonicida ◽  
Cellulolytic Bacteria ◽  
Bacterial Strains ◽  
Endoglucanase Activity ◽  
Nannochloropsis Gaditana ◽  
Enzymatic Pretreatment ◽  
Whole Cell ◽  
Content Type

ABSTRACTIn this study, we designed and evaluated a microalgal pretreatment method using cellulolytic bacteria that naturally degrades microalgae in their native habitat. Bacterial strains were isolated from each of two mollusk species in a medium containing 1% carboxymethyl cellulose agar. We selected nine bacterial strains that had endoglucanase activity: five strains fromMytilus chilensis, a Chilean mussel, and four strains fromMesodesma donacium, a clam found in the Southern Pacific. These strains were identified phylogenetically as belonging to the generaAeromonas,Pseudomonas,Chryseobacterium, andRaoultella. The cellulase-producing capacities of these strains were characterized, and the degradation of cell walls inBotryococcus brauniiandNannochloropsis gaditanawas tested with “whole-cell” cellulolytic experiments.Aeromonas bivalviumMA2,Raoultella ornithinolyticaMA5, andAeromonas salmonicidaMC25 degradedB. braunii, andR. ornithinolyticaMC3 and MA5 degradedN. gaditana. In addition,N. gaditanawas pretreated withR. ornithinolyticastrains MC3 and MA5 and was then subjected to an anaerobic digestion process, which increased the yield of methane by 140.32% and 158.68%, respectively, over that from nonpretreated microalgae. Therefore, a “whole-cell” cellulolytic pretreatment can increase the performance and efficiency of biogas production.

Endoglucanase activity of cellulolytic bacteria from lake sediments and its application in hydrophyte degradation

2020 ◽  
Author(s):  
Hongpei Zhang ◽  
Qianzheng Li ◽  
Yuqing Zhao ◽  
Mingzhen Zhang ◽  
Dong Xu ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Hydrilla Verticillata ◽  
Aquatic Organisms ◽  
Plant Residue ◽  
Plant Residues ◽  
Cellulose Content ◽  
Cellulolytic Bacteria ◽  
Bacterial Strains ◽  
Submerged Plants ◽  
Endoglucanase Activity

Abstract Hydrophytes are plants that grow in or on water. Their overgrowth adversely affects the ecosystem because of crowding out other aquatic organisms and polluting the environment with plant residue. In principle, cellulolytic bacteria can be used to degrade hydrophyte biomass. We here isolated and characterized four cellulolytic bacterial strains from Lake Donghu sediments (Wuhan, China) that are rich in organic matter and plant residues. The isolates (WDHS-01 to 04) represent Bacillus, Micromonospora, and Streptomyces genera. The bacteria exhibited pronounced endoglucanase activities (from 0.022 to 0.064 U mL–1). They did not extensively degrade the emerged plant Canna indica L. However, in an Hydrilla verticillata (submerged plant) degradation medium, strain WDHS-02 exhibited a high degradation rate (54.91%), endoglucanase activity of 0.35 U mL–1 and the conversion rate of cellulose to reducing sugars of 7.15%. Correlation analysis revealed that bacterial endoglucanase activity was significantly correlated with the degradation rate, and acid detergent lignin, ash and cellulose content of the residual H. verticillata powder. In conclusion, the identified bacteria efficiently decomposed submerged plants without the need for acid–base pretreatment. They expand the set of known cellulolytic bacteria and can be used for natural degradation of submerged plants.

scholarly journals Isolation and Characterization of Ochrobactrum tritici for Penicillin V Potassium Degradation

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Peng Wang ◽  
Chen Shen ◽  
Kaili Xu ◽  
Qinqin Cong ◽  
Zhe Dong ◽  
...  
Keyword(s):  
Human Health ◽  
Degradation Rate ◽  
Bacterial Strains ◽  
Whole Cell ◽  
Content Type ◽  
Penicillin V ◽  
Isolation And Characterization ◽  
Biodegradation Process ◽  
Degradation Ability ◽  
Ochrobactrum Tritici

ABSTRACT Substantial concentrations of penicillin V potassium (PVK) have been found in livestock manure, soil, and wastewater effluents, which may pose potential threats to human health and contribute to the emergence of penicillin-resistant bacterial strains. In this study, bacterial strains capable of degrading PVK were isolated from sludge and characterized. Strain X-2 was selected for biodegradation of PVK. Based on morphological observations and 16S rRNA gene sequencing, strain X-2 was identified as an Ochrobactrum tritici strain. To enhance the PVK degradation ability of PVK, a whole-cell biodegradation process of Ochrobactrum tritici X-2 was established and optimized. In the whole-cell biodegradation process, the optimal temperature and pH were 30°C and 7.0, respectively. Under the optimized conditions, the degradation rate using 0.5 mg/ml PVK reached 100% within 3 h. During biodegradation, two major metabolites were detected: penicilloic acid and phenolic acid. The present study provides a novel method for the biodegradation of PVK using Ochrobactrum tritici strains, which represent promising candidates for the industrial biodegradation of PVK. IMPORTANCE Substantial concentrations of penicillin V potassium (PVK) have been found in the environment, which may pose potential threats to human health and contribute to the emergence of penicillin-resistant bacterial strains. In this study, antibiotic-degrading bacterial strains for PVK were isolated from sludge and characterized. Ochrobactrum tritici was selected for the biodegradation of PVK with high efficiency. To enhance its PVK degradation ability, a whole-cell biodegradation process was established and optimized using Ochrobactrum tritici. The degradation rate with 0.5 mg/ml PVK reached 100% within 3 h. The potential biodegradation pathway was also investigated. To the best of our knowledge, the present study provides new insights into the biodegradation of PVK using an Ochrobactrum tritici strain, a promising candidate strain for the industrial biodegradation of β-lactam antibiotics.

scholarly journals Ecological Importance of Cross-Feeding of the Intermediate Metabolite 1,2-Propanediol between Bacterial Gut Symbionts

2020 ◽  
Vol 86 (11) ◽  
Author(s):  
Christopher C. Cheng ◽  
Rebbeca M. Duar ◽  
Xiaoxi Lin ◽  
Maria Elisa Perez-Munoz ◽  
Stephanie Tollenaar ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Lactobacillus Reuteri ◽  
Trophic Interaction ◽  
Bacterial Strains ◽  
Content Type ◽  
Bifidobacterium Breve ◽  
Gut Symbionts ◽  
Gnotobiotic Mice ◽  
Ecological Importance ◽  
Isogenic Mutants

ABSTRACT Cross-feeding based on the metabolite 1,2-propanediol has been proposed to have an important role in the establishment of trophic interactions among gut symbionts, but its ecological importance has not been empirically established. Here, we show that in vitro growth of Lactobacillus reuteri (syn. Limosilactobacillus reuteri) ATCC PTA 6475 is enhanced through 1,2-propanediol produced by Bifidobacterium breve UCC2003 and Escherichia coli MG1655 from the metabolization of fucose and rhamnose, respectively. Work with isogenic mutants showed that the trophic interaction is dependent on the pduCDE operon in L. reuteri, which encodes the ability to use 1,2-propanediol, and the l-fucose permease (fucP) gene in B. breve, which is required for 1,2-propanediol formation from fucose. Experiments in gnotobiotic mice revealed that, although the pduCDE operon bestows a fitness burden on L. reuteri ATCC PTA 6475 in the mouse digestive tract, the ecological performance of the strain was enhanced in the presence of B. breve UCC2003 and the mucus-degrading species Bifidobacterium bifidum. The use of the respective pduCDE and fucP mutants of L. reuteri and B. breve in the mouse experiments indicated that the trophic interaction was specifically based on 1,2-propanediol. Overall, our work established the ecological importance of cross-feeding relationships based on 1,2-propanediol for the fitness of a bacterial symbiont in the vertebrate gut. IMPORTANCE Through experiments in gnotobiotic mice that employed isogenic mutants of bacterial strains that produce (Bifidobacterium breve) and utilize (Lactobacillus reuteri) 1,2-propanediol, this study provides mechanistic insight into the ecological ramifications of a trophic interaction between gut symbionts. The findings improve our understanding on how cross-feeding influences the competitive fitness of L. reuteri in the vertebrate gut and revealed a putative selective force that shaped the evolution of the species. The findings are relevant since they provide a basis to design rational microbial-based strategies to modulate gut ecosystems, which could employ mixtures of bacterial strains that establish trophic interactions or a personalized approach based on the ability of a resident microbiota to provide resources for the incoming microbe.

Integration of enzymatic pretreatment and sludge co-digestion in biogas production from microalgae

2021 ◽  
Vol 124 ◽  
pp. 254-263
Author(s):  
Romina Avila ◽  
Elvira Carrero ◽  
Teresa Vicent ◽  
Paqui Blánquez
Keyword(s):  
Biogas Production ◽  
Enzymatic Pretreatment

scholarly journals Identification and Characterization of the First Virulent Phages, Including a Novel Jumbo Virus, Infecting Ochrobactrum spp.

2020 ◽  
Vol 21 (6) ◽  
pp. 2096
Author(s):  
Przemyslaw Decewicz ◽  
Piotr Golec ◽  
Mateusz Szymczak ◽  
Monika Radlinska ◽  
Lukasz Dziewit
Keyword(s):  
Dna Methyltransferase ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Genome Mining ◽  
Sewage Sample ◽  
Bacterial Strains ◽  
Regulatory Circuits ◽  
A Genome ◽  
Insightful Analysis

The Ochrobactrum genus consists of an extensive repertoire of biotechnologically valuable bacterial strains but also opportunistic pathogens. In our previous study, a novel strain, Ochrobactrum sp. POC9, which enhances biogas production in wastewater treatment plants (WWTPs) was identified and thoroughly characterized. Despite an insightful analysis of that bacterium, its susceptibility to bacteriophages present in WWTPs has not been evaluated. Using raw sewage sample from WWTP and applying the enrichment method, two virulent phages, vB_OspM_OC and vB_OspP_OH, which infect the POC9 strain, were isolated. These are the first virulent phages infecting Ochrobactrum spp. identified so far. Both phages were subjected to thorough functional and genomic analyses, which allowed classification of the vB_OspM_OC virus as a novel jumbo phage, with a genome size of over 227 kb. This phage encodes DNA methyltransferase, which mimics the specificity of cell cycle regulated CcrM methylase, a component of the epigenetic regulatory circuits in Alphaproteobacteria. In this study, an analysis of the overall diversity of Ochrobactrum-specific (pro)phages retrieved from databases and extracted in silico from bacterial genomes was also performed. Complex genome mining allowed us to build similarity networks to compare 281 Ochrobactrum-specific viruses. Analyses of the obtained networks revealed a high diversity of Ochrobactrum phages and their dissimilarity to the viruses infecting other bacteria.

scholarly journals Electroactivity of Phototrophic River Biofilms and Constitutive Cultivable Bacteria

2011 ◽  
Vol 77 (15) ◽  
pp. 5394-5401 ◽  
Author(s):  
Emilie Lyautey ◽  
Amandine Cournet ◽  
Soizic Morin ◽  
Stéphanie Boulêtreau ◽  
Luc Etcheverry ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Cyclic Voltammetry ◽  
Oxygen Reduction ◽  
Saturated Calomel Electrode ◽  
Bacterial Strains ◽  
Phenotypic Properties ◽  
Content Type ◽  
Population Scale ◽  
River Biofilm ◽  
Biofilm Development

ABSTRACTElectroactivity is a property of microorganisms assembled in biofilms that has been highlighted in a variety of environments. This characteristic was assessed for phototrophic river biofilms at the community scale and at the bacterial population scale. At the community scale, electroactivity was evaluated on stainless steel and copper alloy coupons used both as biofilm colonization supports and as working electrodes. At the population scale, the ability of environmental bacterial strains to catalyze oxygen reduction was assessed by cyclic voltammetry. Our data demonstrate that phototrophic river biofilm development on the electrodes, measured by dry mass and chlorophyllacontent, resulted in significant increases of the recorded potentials, with potentials of up to +120 mV/saturated calomel electrode (SCE) on stainless steel electrodes and +60 mV/SCE on copper electrodes. Thirty-two bacterial strains isolated from natural phototrophic river biofilms were tested by cyclic voltammetry. Twenty-five were able to catalyze oxygen reduction, with shifts of potential ranging from 0.06 to 0.23 V, cathodic peak potentials ranging from −0.36 to −0.76 V/SCE, and peak amplitudes ranging from −9.5 to −19.4 μA. These isolates were diversified phylogenetically (Actinobacteria,Firmicutes,Bacteroidetes, andAlpha-,Beta-, andGammaproteobacteria) and exhibited various phenotypic properties (Gram stain, oxidase, and catalase characteristics). These data suggest that phototrophic river biofilm communities and/or most of their constitutive bacterial populations present the ability to promote electronic exchange with a metallic electrode, supporting the following possibilities: (i) development of electrochemistry-based sensors allowingin situphototrophic river biofilm detection and (ii) production of microbial fuel cell inocula under oligotrophic conditions.

scholarly journals Natural Disruption of Two Regulatory Networks in Serotype M3 Group A Streptococcus Isolates Contributes to the Virulence Factor Profile of This Hypervirulent Serotype

2014 ◽  
Vol 82 (5) ◽  
pp. 1744-1754 ◽  
Author(s):  
Tram N. Cao ◽  
Zhuyun Liu ◽  
Tran H. Cao ◽  
Kathryn J. Pflughoeft ◽  
Jeanette Treviño ◽  
...  
Keyword(s):  
Virulence Factor ◽  
Regulatory Networks ◽  
Molecular Mechanisms ◽  
Group A Streptococcus ◽  
Regulatory System ◽  
Mrna Levels ◽  
Bacterial Strains ◽  
Content Type ◽  
Small Regulatory Rna ◽  
Group A

ABSTRACTDespite the public health challenges associated with the emergence of new pathogenic bacterial strains and/or serotypes, there is a dearth of information regarding the molecular mechanisms that drive this variation. Here, we began to address the mechanisms behind serotype-specific variation between serotype M1 and M3 strains of the human pathogenStreptococcus pyogenes(the group AStreptococcus[GAS]). Spatially diverse contemporary clinical serotype M3 isolates were discovered to contain identical inactivating mutations within genes encoding two regulatory systems that control the expression of important virulence factors, including the thrombolytic agent streptokinase, the protease inhibitor-binding protein-G-related α2-macroglobulin-binding (GRAB) protein, and the antiphagocytic hyaluronic acid capsule. Subsequent analysis of a larger collection of isolates determined that M3 GAS, since at least the 1920s, has harbored a 4-bp deletion in thefasCgene of thefasBCAXregulatory system and an inactivating polymorphism in therivRregulator-encoding gene. ThefasCandrivRmutations in M3 isolates directly affect the virulence factor profile of M3 GAS, as evident by a reduction in streptokinase expression and an enhancement of GRAB expression. Complementation of thefasCmutation in M3 GAS significantly enhanced levels of the small regulatory RNA FasX, which in turn enhanced streptokinase expression. Complementation of therivRmutation in M3 GAS restored the regulation ofgrabmRNA abundance but did not alter capsule mRNA levels. While important, thefasCandrivRmutations do not provide a full explanation for why serotype M3 strains are associated with unusually severe invasive infections; thus, further investigation is warranted.

scholarly journals Effects of Methanogenic Inhibitors on Methane Production and Abundances of Methanogens and Cellulolytic Bacteria inIn VitroRuminal Cultures

2011 ◽  
Vol 77 (8) ◽  
pp. 2634-2639 ◽  
Author(s):  
Zhenming Zhou ◽  
Qingxiang Meng ◽  
Zhongtang Yu
Keyword(s):  
Methane Production ◽  
Volatile Fatty Acids ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Cellulolytic Bacteria ◽  
Bacterial Populations ◽  
Content Type ◽  
Specific Pcr ◽  
Methanogen Population ◽  
Propynoic Acid

ABSTRACTThe objective of this study was to systematically evaluate and compare the effects of select antimethanogen compounds on methane production, feed digestion and fermentation, and populations of ruminal bacteria and methanogens usingin vitrocultures. Seven compounds, including 2-bromoethanesulphonate (BES), propynoic acid (PA), nitroethane (NE), ethyltrans-2-butenoate (ETB), 2-nitroethanol (2NEOH), sodium nitrate (SN), and ethyl-2-butynote (EB), were tested at a final concentration of 12 mM. Ground alfalfa hay was included as the only substrate to simulate daily forage intake. Compared to no-inhibitor controls, PA, 2NEOH, and SN greatly reduced the production of methane (70 to 99%), volatile fatty acids (VFAs; 46 to 66%), acetate (30 to 60%), and propionate (79 to 82%), with 2NEOH reducing the most. EB reduced methane production by 23% without a significant effect on total VFAs, acetate, or propionate. BES significantly reduced the propionate concentration but not the production of methane, total VFAs, or acetate. ETB or NE had no significant effect on any of the above-mentioned measurements. Specific quantitative-PCR (qPCR) assays showed that none of the inhibitors significantly affected total bacterial populations but that they did reduce theFibrobacter succinogenespopulation. SN reduced theRuminococcus albuspopulation, while PA and 2NEOH increased the populations of bothR. albusandRuminococcus flavefaciens. Archaeon-specific PCR-denaturing gradient gel electrophoresis (DGGE) showed that all the inhibitors affected the methanogen population structure, while archaeon-specific qPCR revealed a significant decrease in methanogen population in all treatments. These results showed that EB, ETB, NE, and BES can effectively reduce the total population of methanogens but that they reduce methane production to a lesser extent. The results may guide futureinvivostudies to develop effective mitigation of methane emission from ruminants.

scholarly journals In VitroandIn VivoCharacterization of the Novel Oxabicyclooctane-Linked Bacterial Topoisomerase Inhibitor AM-8722, a Selective, Potent Inhibitor of Bacterial DNA Gyrase

2016 ◽  
Vol 60 (8) ◽  
pp. 4830-4839 ◽  
Author(s):  
Christopher M. Tan ◽  
Charles J. Gill ◽  
Jin Wu ◽  
Nathalie Toussaint ◽  
Jingjun Yin ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Antibacterial Agents ◽  
Cell Activity ◽  
Dna Gyrase ◽  
Topoisomerase Iv ◽  
Bacterial Dna ◽  
Whole Cell ◽  
Content Type

ABSTRACTOxabicyclooctane-linked novel bacterial topoisomerase inhibitors (NBTIs) represent a new class of recently described antibacterial agents with broad-spectrum activity. NBTIs dually inhibit the clinically validated bacterial targets DNA gyrase and topoisomerase IV and have been shown to bind distinctly from known classes of antibacterial agents directed against these targets. Herein we report the molecular, cellular, andin vivocharacterization of AM-8722 as a representative N-alkylated-1,5-naphthyridone left-hand-side-substituted NBTI. Consistent with its mode of action, macromolecular labeling studies revealed a specific effect of AM-8722 to dose dependently inhibit bacterial DNA synthesis. AM-8722 displayed greater intrinsic enzymatic potency than levofloxacin versus both DNA gyrase and topoisomerase IV fromStaphylococcus aureusandEscherichia coliand displayed selectivity against human topoisomerase II. AM-8722 was rapidly bactericidal and exhibited whole-cell activity versus a range of Gram-negative and Gram-positive organisms, with no whole-cell potency shift due to the presence of DNA or human serum. Frequency-of-resistance studies demonstrated an acceptable rate of resistance emergencein vitroat concentrations 16- to 32-fold the MIC. AM-8722 displayed acceptable pharmacokinetic properties and was shown to be efficacious in mouse models of bacterial septicemia. Overall, AM-8722 is a selective and potent NBTI that displays broad-spectrum antimicrobial activityin vitroandin vivo.

Sign in / Sign up

Export Citation Format

Share Document