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Nicolas Chabert, Violaine Bonnefoy, Wafa Achouak
Acidithiobacillus ferrooxidans is a strict acidophilic chemolithoautotrophic bacterium that obtains its energy from reduced inorganic sulfur species or ferrous iron oxidation under aerobic conditions. Carbon felt electrodes were pre-colonized by A. ferrooxidansATCC 23270(T) using ferrous iron or sulfur as electron donors, via the addition (or not) of a mixture of C14 acyl-homoserine lactones (C14-AHLs). Electrode coverage during pre-colonization was sparse regardless of the electron donor source, whereas activation of quorum sensing significantly enhanced it...
September 19, 2017: Microbial Biotechnology
Marta Potrykus, Nicole Hugouvieux-Cotte-Pattat, Ewa Lojkowska
Bacteria from the genus Dickeya cause severe symptoms on numerous economically important plants. D. solani is the Dickeya species most frequently found on infected potato plants in Europe. D. solani strains from different countries show high genetic homogeneity but significant differences in their virulence level. Dickeya species possess two quorum sensing (QS) mechanisms: the Exp system based on classic N-acyl-homoserine lactone (AHL) signals and a specific system depending on the production and perception of a molecule of unknown structure, Virulence Factor Modulating (VFM)...
September 18, 2017: Molecular Plant Pathology
Na Liu, Min Yu, Youbin Zhao, Jingguang Cheng, Ke An, Xiao-Hua Zhang
Many bacteria, such as Proteobacteria, Cyanobacteria and Bacteroidetes, use N-acylhomoserine lactones (AHLs) as quorum-sensing (QS) signal molecules for communication. Enzymatic degradation of AHLs, such as AHL acylase and AHL lactonase, can degrade AHLs (quorum quenching, QQ) to attenuate or disarm the virulence of pathogens. QQ is confirmed to be common in marine bacterial communities. Many genes encoding AHL acylases are found in marine bacteria and metagenomic collections, but only a few of these have been characterized in detail...
September 18, 2017: Microbiology
A M Lees, J C Lees, A T Lisle, M L Sullivan, J B Gaughan
Thirty-six steers (12 of each Angus, Charolais, and Brahman) with an initial BW of 318.5 ± 6.7 kg were used in a 130-day study. Two treatments were imposed: un-shaded and shaded (3 m(2)/animal; 90% solar block shade cloth). On day 1, steers were administered with rumen temperature boluses. Rumen temperatures (T RUM) were obtained at 10 min intervals over the duration of the study to determine differences in T RUM between Bos indicus and Bos taurus cattle. Six feedlot pens (162 m(2)) were used with six steers (2/breed) per pen with three pens/treatment...
September 16, 2017: International Journal of Biometeorology
Brett L Mellbye, Eva Spieck, Peter J Bottomley, Luis A Sayavedra-Soto
The genomes of many bacteria that participate in nitrogen cycling through the process of nitrification contain putative genes associated with acyl-homoserine lactone (AHL) quorum sensing (QS). AHL QS or bacterial cell-cell signaling is a method of bacterial communication and gene regulation and may be involved in nitrogen oxide fluxes or other important phenotypes in nitrifying bacteria. Here, we carried out a broad survey of AHL production in nitrifying bacteria in three steps. First, we analyzed the evolutionary history of AHL synthase and AHL receptor homologs in sequenced genomes and metagenomes of nitrifying bacteria to identify AHL synthase homologs in ammonia-oxidizing bacteria (AOB) of the genera Nitrosospira and nitrite-oxidizing bacteria (NOB) of the genera Nitrococcus, Nitrobacter, and Nitrospira Next, we screened cultures of both AOB and NOB cultures with uncharacterized AHL synthase genes and AHL synthase-negative nitrifiers by bioassay...
September 8, 2017: Applied and Environmental Microbiology
Md Akil Hossain, Seung-Jin Lee, Na-Hye Park, Abraham Fikru Mechesso, Biruk Tesfaye Birhanu, JeongWoo Kang, Md Ahsanur Reza, Joo-Won Suh, Seung-Chun Park
Quorum sensing (QS) is a cell density-dependent regulation of virulent bacterial gene expression by autoinducers that potentially pertains in the epidemic of bacterial virulence. This study was initially designed to evaluate the effect of 5 phenolic compounds in the modulation of QS and virulence factors of Chromobacterium violaceum and Pseudomonas aeruginosa, and to determine the mechanisms of their effects. Biosensor strains were used to assess antibacterial and anti-QS effect of these compounds. Only methyl gallate (MG) among these compounds demonstrated profound anti-QS effect in the preliminary study, and thus only MG was utilized further to evaluate the effects on the synthesis and activity of acyl homoserine lactone (AHL) in C...
September 6, 2017: Scientific Reports
Julianne Megaw, Brendan F Gilmore
Persister cells are phenotypic variants within a microbial population, which are dormant and transiently tolerant to stress. Persistence has been studied extensively in bacteria, and in eukaryotes to a limited extent, however, it has never been observed in archaea. Using the model haloarchaeon, Haloferax volcanii DS2, we demonstrated persister cell formation in this domain, with time-kill curves exhibiting a characteristic biphasic pattern following starvation or exposure to lethal concentrations of various biocidal compounds...
2017: Frontiers in Microbiology
Yu-Sheng Li, Xin-Rong Pan, Jia-Shun Cao, Xiang-Ning Song, Fang Fang, Zhong-Hua Tong, Wen-Wei Li, Han-Qing Yu
Quorum sensing (QS), especially acyl homoserine lactone (AHL)-mediated QS, in activated sludge arouses great interests because of its vital role in the formation of biofilm and aerobic granules (AG). Although QS is reported to be largely related to the properties of activated sludge, it is not economically feasible to tune QS in an activated sludge reactor through dosing pure AHL or AHL hydrolase. A more reasonable way to tune QS is to augment reactors with AHL-producing or -quenching bacteria. In this work, the impacts of continuous dose of AHL-producing or -quenching strains on the activated sludge during its granulation process were explored...
August 29, 2017: Water Research
D D Kulkarni, C D Ahl, A M Shore, A J Miller, J E Harriss, C E Sosolik, J P Marler
Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy)...
August 2017: Review of Scientific Instruments
Jinfeng Wang, Lili Ding, Kan Li, Hui Huang, Haidong Hu, Jinju Geng, Ke Xu, Hongqiang Ren
Quorum sensing (QS) signaling, plays a significant role in regulating formation of biofilms in the nature; however, little information about the occurrence and distribution of quorum sensing molecular in the biofilm of carriers has been reported. In this study, distribution of QS signaling molecules (the acylated homoserine lactones-AHLs, and AI-2), extracellular polymeric substances (EPS) and the mechanical properties in sequencing batch biofilm reactor (SBBR) biofilms have been investigated. Using increased centrifugal force, the biofilms were detached into different fractions...
August 28, 2017: Science of the Total Environment
Jan Leipert, Christian Treitz, Matthias Leippe, Andreas Tholey
N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)...
August 30, 2017: Journal of the American Society for Mass Spectrometry
Ji Zheng, Tao Chen, Hong Chen
The contamination of antibiotic resistance genes (ARGs) in drinking water may pose a direct threat to human health. This study applied high-throughput qPCR and sequencing to investigate the dynamics of ARGs and bacterial communities during the advanced treatment of drinking water using biological activated carbon. The promotion of ARGs was observed, and the normalized copy number of ARGs increased significantly after BAC treatment, raising the number of detected ARGs from 84 to 159. Twenty-nine ARGs were identified as biofilm-influencing sources in the BAC, and they persisted after chlorination...
August 24, 2017: Science of the Total Environment
Caili Zhang, Suqin Zhu, Abdul-Nabi Jatt, Yurong Pan, Mingyong Zeng
Shewanella spp. are the common spoilage organisms found in aquatic food products stored at low temperature and their spoilage mechanism has been reported to be mediated by quorum sensing (QS). However, the specifically expressed proteins responding to N-acyl homoserine-lactone (AHLs) were seldom reported. The present study aims to evaluate the effects of different AHL signal molecules on Shewanella putrefaciens Z4 isolated from refrigerated turbot (Scophthalmus maximus) at the proteome level. The results revealed that exogenous AHLs were utilized as QS signal molecules by S...
August 21, 2017: Letters in Applied Microbiology
Richard E Ahl, Yarrow Dunham
Young children show social preferences for resource-rich individuals, although few studies have explored the causes underlying such preferences. We evaluate the viability of one candidate cause: Children believe that resource wealth relates to behavior, such that they expect the resource rich to be more likely to materially benefit others (including themselves) than the resource poor. In Studies 1 and 2 (ages 4-10), American children from predominantly middle-income families (n = 94) and Indian children from lower income families (n = 30) predicted that the resource rich would be likelier to share with others than the resource poor...
August 21, 2017: Child Development
Joseph P Gerdt, Danielle M Wittenwyler, Joshua B Combs, Michelle E Boursier, Jacob W Brummond, He Xu, Helen E Blackwell
Cell-cell signaling between bacteria, including quorum-sensing (QS) communication systems, may play a role in the establishment and maintenance of polymicrobial communities. To better understand and model these interactions, we must uncover the degree to which neighboring species recognize each another's signals. In the current study, we tested the likelihood of whether the QS systems of two opportunistic pathogens (Acinetobacter baumannii and Pseudomonas aeruginosa) that frequently arise in polymicrobial infections would be affected by the QS signals of neighboring species...
September 15, 2017: ACS Chemical Biology
Yoshiaki Yasutake, Hiroyuki Kusada, Teppei Ebuchi, Satoshi Hanada, Yoichi Kamagata, Tomohiro Tamura, Nobutada Kimura
Understanding the molecular mechanisms of bacterial antibiotic resistance will help prepare against further emergence of multi-drug resistant strains. MacQ is an enzyme responsible for the multi-drug resistance of Acidovorax sp. strain MR-S7. MacQ has acylase activity against both N-acylhomoserine lactones (AHLs), a class of signalling compounds involved in quorum sensing, and β-lactam antibiotics. Thus, MacQ is crucial as a quencher of quorum sensing as well as in conferring antibiotic resistance in Acidovorax...
August 21, 2017: Scientific Reports
Jessica M Stine, Gabriel J H Ahl, Casey Schlenker, Domnita-Valeria Rusnac, Klára Briknarová
Anastellin is a small recombinant fragment derived from the extracellular matrix protein fibronectin; it comprises the first type III (FN3) domain without the two N-terminal β-strands. It inhibits angiogenesis, tumor growth, and metastasis in mouse models and requires endogenous fibronectin for its in vivo anti-angiogenic activity. It binds to fibronectin in vitro and converts the soluble protein to insoluble fibrils that structurally and functionally resemble fibronectin fibrils deposited in the extracellular matrix by cells...
September 5, 2017: Biochemistry
Ting Ding, Tingting Li, Zhi Wang, Jianrong Li
Aeromonas sobria is opportunistic pathogen frequently found in environment and food. Interfering with its quorum sensing (QS) system could be a promising way to alleviate its virulence. In this study, curcumin liposomes were prepared and their characteristics like particle size, zeta potential, PDI (Polymey Disperse Index), encapsulation efficiency and loading capacity were measured. The quorum sensing inhibitory effect of curcumin liposomes under sub-MIC (Minimum Inhibitory Concentration) on siderophore production, swimming and swarming motility, extracellular proteases, biofilm formation and AHLs (N-acylhomoserine lactones) production of A...
August 17, 2017: Scientific Reports
Qiuhong Huang, Yongkang Ou, Hao Xiong, Haidi Yang, Zhigang Zhang, Suijun Chen, Yongyi Ye, Yiqing Zheng
HYPOTHESIS: The miR-34a/Bcl-2 signaling pathway may play a role in the mechanisms related to age-related hearing loss (AHL) in the auditory cortex. BACKGROUND: The auditory cortex plays a key role in the recognition and processing of complex sound. It is difficult to explain why patients with AHL have poor speech recognition, so increasing numbers of studies have focused on its central change. Although micro (mi)RNAs in the central nervous system have recently been increasingly reported to be associated with age-related diseases, the molecular mechanisms of AHL in the auditory cortex are not fully understood...
2017: Audiology & Neuro-otology
So Ishizaki, Ryoichi Sugiyama, Satoshi Okabe
Membrane fouling still remains a major obstacle for wider applications of membrane bioreactor (MBR), which is mainly caused by soluble microbial products (SMP). Identification of key bacteria responsible for SMP production is essential for mitigation of membrane fouling. Here, we investigated the effect of microbial interaction on membrane fouling. We measured the membrane fouling potentials of 13 bacterial strains isolated from a pilot-scale MBR treating domestic wastewater when they were cultivated as single-culture and co-culture...
August 16, 2017: Scientific Reports
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