Search results for "bacteria."

Okadaic Acid, an Apoptogenic Toxin for Symbiotic/Parasitic Annelids in the Demosponge Suberites domuncula

2006

ABSTRACT The role of okadaic acid (OA) in the defense system of the marine demosponge Suberites domuncula against symbiotic/parasitic annelids was examined. Bacteria within the mesohyl produced okadaic acid at concentrations between 32 ng/g and 58 ng/g of tissue (wet weight). By immunocytochemical methods and by use of antibodies against OA, we showed that the toxin was intracellularly stored in vesicles. Western blotting experiments demonstrated that OA also existed bound to a protein with a molecular weight of 35,000 which was tentatively identified as a galectin (by application of antigalectin antibodies). Annelids that are found in S. domuncula undergo apoptotic cell death. OA is one ca…

Bioaccessibility Study of Aflatoxin B1 and Ochratoxin A in Bread Enriched with Fermented Milk Whey and/or Pumpkin

2021

The presence of mycotoxins in cereals and cereal products remains a significant issue. The use of natural ingredients such as pumpkin and whey, which contain bioactive compounds, could be a strategy to reduce the use of conventional chemical preservatives. The aim of the present work was to study the bioaccessibility of aflatoxin B1 (AFB1) and ochratoxin (OTA) in bread, as well as to evaluate the effect of milk whey (with and without lactic acid bacteria fermentation) and pumpkin on reducing mycotoxins bioaccessibility. Different bread typologies were prepared and subjected to an in vitro digestion model. Gastric and intestinal extracts were analyzed by HPLC–MS/qTOF and mycotoxins bio…

Blue-green algalike cells associated with the tunic of Ciona intestinalis L.

1980

Certain organisms resembling blue-green algae embedded in the tunic of the solitary ascidian Ciona intestinalis L. are described. Their probable symbiotic role as related to the peculiar habitat of this ascidian is suggested.

Identification and quantification of microbial populations in activated sludge and anaerobic digestion processes

2014

Eight different phenotypes were studied in an activated sludge process (AeR) and anaerobic digester AnD) in a full-scale wastewater treatment plant by means of fluorescent in situ hybridization (FISH) and automated FISH quantification software. The phenotypes were ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, denitrifying bacteria, phosphate-accumulating organisms (PAO), glycogen-accumulating organisms (GAO), sulphate-reducing bacteria (SRB), methanotrophic bacteria and methanogenic archaea. Some findings were unexpected: (a) Presence of PAO, GAO and denitrifiers in the AeR possibly due to unexpected environmental conditions caused by oxygen deficiencies or its ability to survive …

Immunization of rainbow trout, Oncorhynchus mykiss (Walbaum), with a low molecular mass fraction isolated from Flavobacterium psychrophilum.

2008

Flavobacterium psychrophilum, the causative agent of rainbow trout fry syndrome has become a widespread fish pathogen in freshwater aquaculture worldwide. In this study, a low molecular mass fraction (P25-33), with an approximate weight of 25-33 kDa, was identified among F. psychrophilum strains in an immunoblotting analysis with anti-F. psychrophilum sera. The immunogenic efficacy of the isolated and extracted P25-33 was investigated in two intraperitoneal immunization trials with rainbow trout, Oncorhynchus mykiss (Walbaum). The first trial included immunizations using P25-33 with Freund's complete adjuvant (FCA) and the second trial included immunizations using P25-33, formalin-inactivat…

Cell Envelopes of Methanogens

2010

Methanogens play an important role in the global carbon cycle, because they are involved in the last step of anaerobic degradation of organic material to methane. Although the first report on methane emanation from aquatic muds was given by Alessandro Volta in the year 1776, the first methanogen was not obtained in pure culture before 1947. Special culture techniques had to be developed for growing the strict anaerobic methanogenic isolates. The methanogens were the first species of the archaeal domain (Archaea) detected. Their unique biochemical and genetic properties have stimulated basic investigations of this microbial group in the last three decades. The methanogenic Archaea possess a …

Pathogenicity of live bacteria and extracellular products of motileAeromonasisolated from eels

1995

The pathogenic activities in vitro and in vivo of live bacteria and extracellular products (ECP) of 24 motile Aeromonas strains were investigated. Most Aer. hydrophila and Aer. jandaei isolates were pathogenic for eels (LD50 105·4‐107·6 cfu fish‐1) but no Aer. sobria, Aer. caviae and Aer. allosaccharophila caused mortality in eels at doses of > 108·4 cfu fish‐1. Of these Aeromonas strains, Aer. hydrophila and Aer. jandaei in particular produced elastases and haemolysins against fish erythrocytes. ECP from Aer. hydrophila and Aer. jandaei caused degenerative changes in fish cell lines and were strongly toxic for eels (LD50 1·0–3·2 μg (g fish)‐1) reproducing the symptoms associated with natur…

Nucleotide sequence of an adult-specific cuticular protein gene from the beetle Tenebrio molitor: effects of 20-hydroxyecdysone on mRNA accumulation.

1993

0962-1075 (Print) Journal Article Research Support, Non-U.S. Gov't; The accumulation of transcripts from two adult-specific cuticular genes (ACP-20 and ACP-22) is shown to be modified after addition of exogenous 20-hydroxyecdysone. In the continuous presence of high levels of the hormone, the expression of ACP-20 gene is significantly weaker than that of untreated controls, while ACP-22 expression is 2.5-fold increased. During active synthesis of the ACP messages, a 0.5 microg 20-hydroxyecdysone injection causes a rapid 2-fold increase in ACP-22 mRNA and is not able to repress ACP-20 mRNA accumulation. We conclude that these genes whose transcripts appear in an almost coordinated manner in …

Essential oils as multi-target compounds for novel food safety strategies

This research work has been developed in the context of the potencial applications of essential oils as multi-target compounds for novel food safety strategies, such as active packaging technologies. Essential oils are aromatic oils derived from plants and usually extracted by hydrodistillation when intended to be used in food. There is an increasing interest in the antimicrobial properties of essential oils due to the possibility of using them to replace ‘synthetic’ preservatives in food or, in general, to reduce viable numbers of pathogens along the food chain.

Photocatalytic activity of N-doped TiO2-based materials embedded with gold NPs for applications in antibacterial photodynamic therapy (aPDT)

Antibacterial photodynamic therapy (aPDT) is a potential treatment for antibiotic-resistant bacterial infections. It is based on the photosensitization of bacterial cells with exogenous agents that, when exposed to light, produce reactive oxygen species (ROS), such as OH-, O2-, H2O2. ROS can induce complex oxidative-reductive chains of reactions, resulting in damage of cellular components in target tissues1. Photocatalysts, like inorganic semiconductor oxides, represent an interesting class of materials to design new strategies for aPTD. As exposed to light of proper wavelengths, photocatalysts induce the formation of electron-hole pairs capable of producing a cascade of reactions suitable …