scholarly journals Polysaccharide hydrolysis in the presence of oil and dispersants: Insights into potential degradation pathways of exopolymeric substances (EPS) from oil-degrading bacteria

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Kai Ziervogel ◽  
Samantha B. Joye ◽  
Sara Kleindienst ◽  
Sairah Y. Malkin ◽  
Uta Passow ◽  
...  
Keyword(s):  
Degradation Products ◽  
Initial Step ◽  
Turnover Rates ◽  
Roller Bottle ◽  
Exopolymeric Substances ◽  
Degrading Bacteria ◽  
Hydrolysis Rates ◽  
Water Treatments ◽  
Polysaccharide Hydrolysis ◽  
Whole Water

Oceanic oil-degrading bacteria produce copious amounts of exopolymeric substances (EPS) that facilitate their access to oil. The fate of EPS in the water column is in part determined by activities of heterotrophic microbes capable of utilizing EPS compounds as carbon and energy sources. To evaluate the potential of natural microbial communities to degrade EPS produced during oil degradation, we measured potential hydrolysis rates of six structurally distinct polysaccharides in two roller bottle experiments, using water from a natural oil seep in the northern Gulf of Mexico. The suite of polysaccharides used to measure the initial step in carbon degradation is indicative of polymers within microbial EPS. The treatments included (i) unamended surface or deep waters (whole water), and water amended with (ii) a water-accommodated fraction of oil (WAF), (iii) oil dispersant Corexit 9500, and (iv) WAF chemically-enhanced with Corexit (CEWAF). The oil and Corexit treatments were employed to simulate conditions during the Deepwater Horizon oil spill. Polysaccharide hydrolysis rates in the surface-water treatments were lowest in the WAF treatment, despite elevated levels of EPS in the form of transparent exopolymer particles (TEP). In contrast, the three deep-water treatments (WAF, Corexit, CEWAF) showed enhanced hydrolysis rates and TEP levels (WAF) compared to the whole water. We also observed variations in the spectrum of polysaccharide-hydrolyzing enzyme activities among the treatments. These substrate specificities were likely driven by activities of oil-degrading bacteria, shaping the pool of EPS and TEP as well as degradation products of hydrocarbons and Corexit compounds. A model calculation of potential turnover rates of organic carbon within the TEP pool suggests extended residence times of TEP in oil-contaminated waters, making them prone to serve as the sticky matrix for oily aggregates known as marine oil snow.

Genomic insights from Monoglobus pectinilyticus: a pectin-degrading specialist bacterium in the human colon

2020 ◽  
Author(s):  
CC Kim ◽  
GR Healey ◽  
WJ Kelly ◽  
ML Patchett ◽  
Z Jordens ◽  
...  
Keyword(s):  
Cell Surface ◽  
Degradation Products ◽  
Model Organism ◽  
Human Colon ◽  
Surface Proteins ◽  
Human Gut ◽  
Pectate Lyases ◽  
Unusual Distribution ◽  
Degrading Bacteria ◽  
Acetyl Esterases

© 2019, International Society for Microbial Ecology. Pectin is abundant in modern day diets, as it comprises the middle lamellae and one-third of the dry carbohydrate weight of fruit and vegetable cell walls. Currently there is no specialized model organism for studying pectin fermentation in the human colon, as our collective understanding is informed by versatile glycan-degrading bacteria rather than by specialist pectin degraders. Here we show that the genome of Monoglobus pectinilyticus possesses a highly specialized glycobiome for pectin degradation, unique amongst Firmicutes known to be in the human gut. Its genome encodes a simple set of metabolic pathways relevant to pectin sugar utilization, and its predicted glycobiome comprises an unusual distribution of carbohydrate-active enzymes (CAZymes) with numerous extracellular methyl/acetyl esterases and pectate lyases. We predict the M. pectinilyticus degradative process is facilitated by cell-surface S-layer homology (SLH) domain-containing proteins, which proteomics analysis shows are differentially expressed in response to pectin. Some of these abundant cell surface proteins of M. pectinilyticus share unique modular organizations rarely observed in human gut bacteria, featuring pectin-specific CAZyme domains and the cell wall-anchoring SLH motifs. We observed M. pectinilyticus degrades various pectins, RG-I, and galactan to produce polysaccharide degradation products (PDPs) which are presumably shared with other inhabitants of the human gut microbiome (HGM). This strain occupies a new ecological niche for a primary degrader specialized in foraging a habitually consumed plant glycan, thereby enriching our understanding of the diverse community profile of the HGM.

A new method for measuring polysaccharide hydrolysis rates in marine environments

1996 ◽  
Vol 25 (1-2) ◽  
pp. 105-115 ◽  
Author(s):  
C. Arnosti
Keyword(s):  
New Method ◽  
Marine Environments ◽  
Hydrolysis Rates ◽  
Polysaccharide Hydrolysis

scholarly journals Biological Degradation of Aflatoxin B1 by Cell-Free Extracts of Bacillus velezensis DY3108 with Broad PH Stability and Excellent Thermostability

Toxins ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 330 ◽  
Author(s):  
Xian Shu ◽  
Yuting Wang ◽  
Qing Zhou ◽  
Minghao Li ◽  
Hao Hu ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Aflatoxin B1 ◽  
High Performance ◽  
Degradation Products ◽  
Sodium Dodecyl ◽  
Aflatoxin Contamination ◽  
Proteinase K ◽  
Biological Degradation ◽  
Bacillus Velezensis ◽  
Degrading Bacteria

(1) Background: Aflatoxin contamination in food and grain poses serious problems both for economic development and public health protection, thus leading to a focus on an effective approach to control it; (2) Methods: Aflatoxin B1 (AFB1) degrading bacteria were isolated using a medium containing coumarin as the sole carbon source, and the biodegradation of AFB1 by the isolate was examined by high performance liquid chromatography, and liquid chromatography mass spectrometry; (3) Results: a bacterial strain exhibiting strong AFB1 degradation activity (91.5%) was isolated and identified as Bacillus velezensis DY3108. The AFB1 degrading activity was predominantly attributed to the cell-free supernatant of strain DY3108. Besides, it was heat-stable and resistant to proteinase K treatment but sensitive to sodium dodecyl sulfate treatment. The optimal temperature for the maximal degradation of AFB1 was 80 °C. Even more notable, the supernatant showed a high level of activity over a broad pH (4.0 to 11.0) and exhibited the highest degradation (94.70%) at pH 8.0. Cytotoxicity assays indicated that the degradation products displayed significantly (p < 0.05) lower cytotoxic effects than the parent AFB1; (4) Conclusions: B. velezensis DY3108 might be a promising candidate for exploitation in AFB1 detoxification and bioremediation in food and feed matrices.

scholarly journals Isolation and Characterization of Microcystin Degrading Bacteria from Holy Ponds in India

2017 ◽  
Vol 4 (4) ◽  
pp. 436-447 ◽  
Author(s):  
Vikram Pal Gandhi ◽  
Anil Kumar
Keyword(s):  
Restriction Analysis ◽  
Water Bodies ◽  
Rrna Gene ◽  
Degrading Bacterium ◽  
Isolation And Characterization ◽  
Chronic Poisoning ◽  
Degrading Bacteria ◽  
Health Related ◽  
Water Treatments

Microcystins (MCs) are toxic cyclic heptapeptides produced by few toxic cyanobacteria and generally form blooms in eutrophic surface fresh water bodies. They cause acute to chronic poisoning and other health related problems mainly by irreversible inhibition of protein phosphatases (PP1 and PP2A) and increased formation of reactive oxygen species (ROS).  Due to limitation of non-biological methods of water treatments the exploration of MCs degrading bacteria is emerging at a quite pace to address, through bioremediation, the problems posed by MCs in water and water-bodies. Report and study of MCs biodegrading bacteria from India were lacking. However it was evident, from our previous study, that microcystin degradation can be achieved by indigenous microcystin degrading bacterial population in its natural place where microcystin producing blooms occur. This study has presented isolation and characterization of indigenous microcystin degrading bacteria from holy ponds in Utter Pradesh of India. Overall 20 bacterial isolates were isolated from Microcystis infested different ponds. Out of these 13 isolates were mlrA positive by PCR and were found to be distinct isolates by amplified ribosomal DNA restriction analysis (ARDRA). However, ARDRA analysis revealed overall four bacterial groups. On the basis of 16S-rRNA gene sequence the Gram-positive-rod isolate PM1 was identified, with 99% identity, as Bacillus licheniformis which was shown earlier to cluster with microcystin degrading bacterium B. subtilis. Thus the present study revealed, for the first time, probable microcystin degrading bacteria in water-bodies from India. The potential and the metabolic pathway of PM1 and other mlrA positive isolates need to be further studied and validated to confirm their application in microcystin bioremediation. Int J Appl Sci Biotechnol, Vol 4(4): 436-447

scholarly journals Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle

2015 ◽  
Vol 112 (44) ◽  
pp. 13591-13596 ◽  
Author(s):  
David J. Lea-Smith ◽  
Steven J. Biller ◽  
Matthew P. Davey ◽  
Charles A. R. Cotton ◽  
Blanca M. Perez Sepulveda ◽  
...  
Keyword(s):  
Crude Oil ◽  
Global Ocean ◽  
Turnover Rates ◽  
Marine Systems ◽  
Dry Cell Weight ◽  
Degrading Bacteria ◽  
Population Sizes ◽  
Global Population ◽  
Dry Cell ◽  
Hydrocarbon Degraders

Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria,ProchlorococcusandSynechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2–540 pg alkanes per mL per day, which translates into a global ocean yield of ∼308–771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities.

scholarly journals Transcriptional regulation of organohalide pollutant utilisation in bacteria

2020 ◽  
Vol 44 (2) ◽  
pp. 189-207 ◽  
Author(s):  
Bruno Maucourt ◽  
Stéphane Vuilleumier ◽  
Françoise Bringel
Keyword(s):  
Transcriptional Regulation ◽  
Degradation Products ◽  
Gene Clusters ◽  
Regulatory Processes ◽  
Content Organization ◽  
Genome Wide ◽  
Degrading Bacteria ◽  
Genes Encoding ◽  
Modulation Of Gene Expression ◽  
Living Organisms

ABSTRACT Organohalides are organic molecules formed biotically and abiotically, both naturally and through industrial production. They are usually toxic and represent a health risk for living organisms, including humans. Bacteria capable of degrading organohalides for growth express dehalogenase genes encoding enzymes that cleave carbon-halogen bonds. Such bacteria are of potential high interest for bioremediation of contaminated sites. Dehalogenase genes are often part of gene clusters that may include regulators, accessory genes and genes for transporters and other enzymes of organohalide degradation pathways. Organohalides and their degradation products affect the activity of regulatory factors, and extensive genome-wide modulation of gene expression helps dehalogenating bacteria to cope with stresses associated with dehalogenation, such as intracellular increase of halides, dehalogenase-dependent acid production, organohalide toxicity and misrouting and bottlenecks in metabolic fluxes. This review focuses on transcriptional regulation of gene clusters for dehalogenation in bacteria, as studied in laboratory experiments and in situ. The diversity in gene content, organization and regulation of such gene clusters is highlighted for representative organohalide-degrading bacteria. Selected examples illustrate a key, overlooked role of regulatory processes, often strain-specific, for efficient dehalogenation and productive growth in presence of organohalides.

Fatty acid metabolism in human fetal placental vasculature

1981 ◽  
Vol 240 (1) ◽  
pp. E65-E71
Author(s):  
T. N. Tulenko ◽  
J. L. Rabinowitz
Keyword(s):  
De Novo ◽  
Neutral Lipids ◽  
Degradation Products ◽  
Vascular Wall ◽  
Chain Elongation ◽  
Synthesis Rate ◽  
Turnover Rates ◽  
Low Oxygen ◽  
Apparent Lack ◽  
Arteries And Veins

The utilization of exogenous acetate and palmitate for the synthesis of vascular wall lipids was studied in isolated blood vessels of the human placenta under high- and low-oxygen conditions. Arteries and veins were obtained from fresh placental material and incubated in Krebs-Henseleit buffer (pH 7.4 at 37 degrees C) containing (in mM) either [2-14C]acetate, 0.11; [1-14C]palmitate, 0.43; or [16-14C]palmitate, 0.43. At the end of the 180-min incubation, neutral lipids accounted for 40%, and phospholipids 60%, of the 14C recovered. Following incubation with either precursor, 14C label was recovered mainly in 16-carbon fatty acids (FA) (35%) and 18-carbon FA (45%); less than 10% was recovered in less than or equal to 14-carbon FA and greater than or equal to 20-carbon FA. Estimates of synthesis rate however indicated that the 18- and 20-carbon FA had the highest turnover rates. Schmidt degradation analysis demonstrated considerable labeling of alkyl carbons after incubation with either carboxyl- or alkyl-labeled precursors, indicating that FA degradation products were used for de novo FA synthesis. Collectively, these findings suggest the presence of both de novo and chain elongation pathways. No differences were observed between arteries and veins, and anoxia had little influence on FA metabolism. Analysis of ATP levels demonstrated elevated concentrations of ATP present, accounting for the apparent lack of anoxic inhibition of FA metabolism.

scholarly journals Biodegradation of Nodularin by a Microcystin-Degrading Bacterium: Performance, Degradation Pathway, and Potential Application

Toxins ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 813
Author(s):  
Mengxuan Yuan ◽  
Qin Ding ◽  
Rongli Sun ◽  
Juan Zhang ◽  
Lihong Yin ◽  
...  
Keyword(s):  
Potential Application ◽  
Degradation Products ◽  
Lake Taihu ◽  
Degradation Mechanism ◽  
Wild Strain ◽  
Order Rate Constant ◽  
Degradation Pathway ◽  
Degrading Bacterium ◽  
Degrading Bacteria ◽  
Degradation Activity

Currently, studies worldwide have comprehensively recognized the importance of Sphingomonadaceae bacteria and the mlrCABD gene cluster in microcystin (MC) degradation. However, knowledge about their degradation of nodularin (NOD) is still unclear. In this study, the degradation mechanism of NOD by Sphingopyxis sp. m6, an efficient MC degrader isolated from Lake Taihu, was investigated in several aspects, including degradation ability, degradation products, and potential application. The strain degraded NOD of 0.50 mg/L with a zero-order rate constant of 0.1656 mg/L/d and a half-life of 36 h. The average degradation rate of NOD was significantly influenced by the temperature, pH, and initial toxin concentrations. Moreover, four different biodegradation products, linear NOD, tetrapeptide H-Glu-Mdhb-MeAsp-Arg-OH, tripeptide H-Mdhb-MeAsp-Arg-OH, and dipeptide H-MeAsp-Arg-OH, were identified, of which the latter two are the first reported. Furthermore, the four mlr genes were upregulated during NOD degradation. The microcystinase MlrA encoded by the mlrA gene hydrolyzes the Arg-Adda bond to generate linear NOD as the first step of NOD biodegradation. Notably, recombinant MlrA showed higher degradation activity and stronger environmental adaptability than the wild strain, suggesting future applications in NOD pollution remediation. This research proposes a relatively complete NOD microbial degradation pathway, which lays a foundation for exploring the mechanisms of NOD degradation by MC-degrading bacteria.

Sign in / Sign up

Export Citation Format

Share Document