Treatment-emergent cefiderocol resistance in carbapenem-resistant Acinetobacter baumannii is associated with insertion sequence ISAba36 in the siderophore receptor pirA.

We report the emergence of cefiderocol resistance in a blaOXA-72 carbapenem-resistant Acinetobacter baumannii isolate from a sacral decubitus ulcer. Cefiderocol was initially used; however, a newly approved sulbactam-durlobactam therapy with source control and flap coverage was successful in treating the infection. Laboratory investigation revealed cefiderocol resistance mediated by ISAba36 insertion into the siderophore receptor pirA.

Detection and Discrimination of DNA Adducts Differing in Size, Regiochemistry, and Functional Group by Nanopore Sequencing.

Chemically induced DNA adducts can lead to mutations and cancer. Unfortunately, because common analytical methods (e.g., liquid chromatography-mass spectrometry) require adducts to be digested or liberated from DNA before quantification, information about their positions within the DNA sequence is lost. Advances in nanopore sequencing technologies allow individual DNA molecules to be analyzed at single-nucleobase resolution, enabling us to study the dynamic of epigenetic modifications and exposure-induced DNA adducts in their native forms on the DNA strand. We applied and evaluated the commercially available Oxford Nanopore Technology (ONT) sequencing platform for site-specific detection of DNA adducts and for distinguishing individual alkylated DNA adducts. Using ONT and the publicly available ELIGOS software, we analyzed a library of 15 plasmids containing site-specifically inserted O6- or N2-alkyl-2'-deoxyguanosine lesions differing in sizes and regiochemistries. Positions of DNA adducts were correctly located, and individual DNA adducts were clearly distinguished from each other.

Effective Preparation Method of Phosphopeptides from Phosvitin and the Analysis of Peptide Profiles Using Tandem Mass Spectrometry.

The effect of high-temperature and mild-pressure (HTMP) pretreatment on the enzymatic hydrolysis of phosvitin and the structural characteristics of the phosphopeptides produced were analyzed using tandem mass spectrometry. The HTMP pretreatment hydrolyzed phosvitin at random sites and helped the subsequent enzyme hydrolysis of the peptides produced. With the HTMP pretreatment alone, 154 peptides were produced, while the use of trypsin, Protex 6L, and Multifect 14L in combination with the pretreatment produced 252, 280, and 164 peptides, respectively. The use of two enzyme combinations (trypsin + Protex 6L and trypsin + Multifect 14L) helped the hydrolysis further. The number of phosphopeptides produced increased when the modifications within the same amino acid sequences were considered. This study indicated that HTMP pretreatment was a breakthrough method to improve the enzymatic hydrolysis of phosvitin that enabled an easy production of phosvitin phosphopeptides for their subsequent functional characterizations.

Antioxidant and anticancer effects of functional peptides from ovotransferrin hydrolysates.

BACKGROUND: Egg white is a good source for making functional peptides that can be used in the food industry. Ovotransferrin (OTF) is one of the major egg white proteins, with many functional properties, including antioxidant, antimicrobial and antiviral activities. However, enzymatic hydrolysis of ovotransferrin is known to further improve the functional activities of OTF. The aim of this study was to investigate the antioxidant and anticancer activities of functional peptides produced by two-step enzyme hydrolysis of OTF. RESULTS: OTF hydrolysates were prepared using promod 278P, thermolysin and a combination of the two enzymes. OTF and OTF hydrolysates showed strong antioxidant activities when analyzed using the DPPH assay. However, only OTF hydrolysates showed a strong free radical scavenging activity when NO- or ABTS-scavenging activity was measured. OTF hydrolysates showed stronger cytotoxic activities than the natural OTF against human cancer cell lines. Furthermore, OTF hydrolysates prepared with promod 278P + thermolysin combination showed the strongest cytotoxic activity, and their IC50 values were 0.79, 0.78, 0.92 and 0.78 mg mL-1 against AGS, LoVo, HT-29 and HeLa, respectively. CONCLUSION: These results indicated that the two-step enzyme hydrolysates of OTF have great potential for use as a food ingredient with antioxidant and anticancer activities. © 2017 Society of Chemical Industry.

New Paenibacillus strain produces a family of linear and cyclic antimicrobial lipopeptides: cyclization is not essential for their antimicrobial activity.

A new bacterial isolate, Paenibacillus sp. OSY-N, showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria. Antimicrobials produced by this strain were purified by reverse-phase high-performance liquid chromatography. Structural analysis, using mass spectrometry, of a single active HPLC fraction revealed two known cyclic lipopeptides (BMY-28160 and permetin A), a new cyclic lipopeptide, and the linear counterparts of these cyclic compounds. The latter were designated as paenipeptins A, B and C, respectively. The paenipeptins have not been reported before as naturally occurring products. Paenipeptins B and C differ at the acyl side chain; paenipeptin C contains a C8-, instead of C7-fatty acyl side chain. To demonstrate unequivocally the antimicrobial activity of the linear forms of this family of cyclic lipopeptides, analogs of the paenipeptins were synthesized chemically and their antimicrobial activity was tested individually. The synthetic linear lipopeptide with an octanoic acid side chain (designated as paenipeptin C΄) showed potent antimicrobial activity with minimum inhibitory concentrations of 0.5-4.0 µg/mL for Gram-negative and 0.5-32 µg/mL for Gram-positive bacteria. Findings demonstrated that peptide cyclization in this lipopeptide family is not essential for their antimicrobial activity. Most importantly, linear lipopeptides are more accessible than their cyclic counterparts through chemical synthesis.

Antioxidant Effect of Extracts from the Coffee Residue in Raw and Cooked Meat.

The residue of ground coffee obtained after the brewing process (spent coffee) still contains various functional components with high antioxidant capacity and health benefits, but no attempts have been made to use it as a resource to produce value-added food ingredients. This study evaluates the antioxidant activity of ethanol or hot water extracts from the residues of coffee after brewing. An extraction experiment was carried out using the conventional solid-liquid methods, including ethanol and water as the extraction media at different temperatures and liquid/solid ratios. The antioxidant activity of extracts was tested for total phenolic compound (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2-thiobarbituric acid reactive substances (TBARS) using oil emulsion and raw/cooked meat systems. The DPPH radical scavenging activity of the ethanol extracts with heating (HEE) and without heating (CEE) were higher than that of the hot water extracts (WE). The highest DPPH value of HEE and CEE at 1000 ppm was 91.22% and 90.21%, respectively. In oil emulsion and raw/cooked systems, both the water and ethanol extracts had similar antioxidant effects to the positive control (BHA), but HEE and CEE extracts showed stronger antioxidant activities than WE extract. These results indicated that the ethanol extracts of coffee residue have a strong antioxidant activity and have the potential to be used as a natural antioxidant in meat.

In vitro antioxidant and mineral-chelating properties of natural and autocleaved ovotransferrin.

BACKGROUND: Egg white proteins can be excellent substrates for the development of functional foods and nutraceuticals. In this study, several in vitro antioxidant methods, namely the ß-carotene linoleate model system, the ferric thiocyanate method, the 2-thiobarbituric acid-reactive substances (TBARS) method and copper/calcium ion chelation, were used to determine the antioxidant capacity of natural and autocleaved ovotransferrin. RESULTS: Autocleaved ovotransferrin was prepared by reducing natural ovotransferrin with tris(2-carboxyethyl)phosphine (TCEP) for 6 h at 37 °C. Autocleaved ovotransferrin suppressed the discoloration of ß-carotene effectively and prevented the oxidation of linoleic acid during 5 days of storage at 4 °C. However, the concentration of autocleaved ovotransferrin had no influence on its antioxidant effect. Similarly, the highest TBARS values were obtained from autocleaved ovotransferrin (>90%) and the lowest value in natural ovotransferrin (24%) during incubation at 37 °C for 48 h. The hydrolysates obtained from autocleaved ovotranferrin showed better copper/calcium-solublilizing activity than those from natural ovotransferrin. CONCLUSION: The results indicated that autocleaved ovotransferrin has the potential to be used as a natural antioxidant in foods.

Cytotoxic and antigenotoxic activities of phosvitin from egg yolk.

Egg yolk phosvitin is one of the most phosphorylated proteins in nature, and thus has a strong metal-binding ability. The objective of this study was to evaluate the cytotoxic and antigenotoxic activities of phosvitin in vitro. Using the 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of phosvitin was evaluated in human cancer cell lines of various tissue origins, including the cervix (HeLa), breast (MCF-7), stomach (AGS), lung (A549 and SK-MES-1), liver (HepG2), and larynx (Hep-2). The growth of all cancer cell lines was inhibited in a dose-dependent manner by phosvitin. Among the cancer cell lines tested, MCF-7 and SK-MES-1 were the least sensitive and HeLa, AGS, and HepG2 were the most sensitive to phosvitin. The 50% inhibition of cell viability values of phosvitin were 5.38, 11.57, 4.78, 6.98, 11.82, 3.93, and 9.97 mg/mL for HeLa, MCF-7, AGS, A549, SK-MES-1, HepG2, and Hep-2, respectively. The protective effects of phosvitin against DNA damage in human leukocytes indicated that phosvitin showed protective effects against the oxidative stress-induced DNA damages in human leukocytes. These results suggested that phosvitin has a high potential to be used as an anticancer agent for humans.