Development and validation of a high performance liquid chromatography-tandem mass spectrometry method for the absolute analysis of 17 α D-amino acids in cooked meals

Stereochemistry of aminoacylated cardiolipins and phosphatidylglycerols from bacteria

Hydrophilic interaction liquid chromatography (HILIC) connected with electrospray high-resolution tandem mass spectrometry (MS) was used for the analysis of unusual amino acid (AA) substituted phosphatidylglycerols (PG) and cardiolipins (CL) in mesophilic and thermophilic bacteria. Individual peaks from the lipid class separation by HILIC were isolated and hydrolyzed to determine the absolute configuration of the aminoacyl side chain. The configuration of the aminoacyl side chain was assigned by indirect liquid chromatography (LC) enantiomer separation after the hydrolysis of the aminoacylated (aminoacyl) lipids using N-(4-nitrophenoxycarbonyl)-l-phenylalanine 2-methoxyethyl ester as chiral derivatizing agent and reversed phase LC-MS for analysis. When two chromatographic methods were combined, less common AAs, such as d-allo-Ile and d-allo-Thr, were identified. The taxonomic classification of bacteria showed that bacteria of the family Bacillaceae (Bacillus and Geobacillus) produce branched-chain AAs, that is, d-allo-Ile, d-Ile, and d-Leu. These AAs were present only in the genera Bacillus and Geobacillus and not in Alicyclobacillus acidoterrestris (family Alicyclobacillaceae). On the contrary, hydroxy AAs, that is, l- and d-Thr, and l- and d-allo-Thr, were identified as aminoacyl-PG and aminoacyl-CL in A. acidoterrestris and were not present in the genera Bacillus and Geobacillus. Therefore, the complete analysis made it possible to identify the stereochemistry of AAs in aminoacyl PGs and CLs and use this fact for chemotaxonomy.

A sensitive and economical method for simultaneous determination of D/L- amino acids profile in foods by HPLC-UV: Application in fermented and unfermented foods discrimination

This work described a sensitive and economical HPLC-UV method with FDAA derivatization to simultaneously detect 36 D/l-amino acids, which provides higher sensitivity and lower cost than other HPLC-based methods. It was validated for linearity range (8-1000 µmol/L), limits of detection (2.68-62.44 pmol/L), limits of quantification (2.93 to 208.13 pmol/L), intraday precision (0.30 % - 5.31 %), interday precision (1.96 % - 8.04 %) and accuracy (86.53 % - 121.46 %). This method was then applied in the determination of D/L- amino acids abundance in fermented and unfermented food materials and showed the characteristics of each type of foods. The method also demonstrated good performance in another application case for the discrimination of different types of food materials based on D/L- amino acids profile. It emphasizes the ability of the method to study the characteristics, distribution and abundance of d-amino acids in foods and their potential application in food quality control.

Bioconversion of bamboo shoot shells through the cultivation of the edible mushrooms Volvariella volvacea

Bamboo shoot shell (BSS), as agricultural waste, is mostly burned or discarded, causing serious environment pollution. In this study, the degradation and utilization of BSS by the edible fungus Volvariella Volvacea was investigated. The composition of V. volvacea fruit body was determined by HPLC-MS, GC-MS and ICP-OES. The activities of CMCase and xylanase were monitored by DNS (3,5-dinitrosalicylic acid) method. Laccase activity was assayed by the oxidation reaction of ABTS [2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)]. The degraded bamboo shoot shell powder was characterized by FTIR and SEM. The results showed that the mycelium of V. volvacea could degrade and utilize BSS for growth. The activities of carboxymethyl cellulase and laccase were increased during the cultivation. At the same time, the physical structure of the shell fiber becames porous and rough. Most of the products of decayed fibers contain alkanes, ethyl or methyl groups. Moreover, the biological efficiency (fruiting body yield) of V. volvacea cultivated on BSS was 1.52-fold higher than that of straw cultivation. The contents of total lipid, elaidic acid (C18:1n-9), total essential amino acids, total amino acids and iron in V. volvacea fruit bodies grown on BSS were 1.11, 1.66, 1.52, 1.60 and 1.30-fold higher than those of straw treatment, respectively. This study provides an effective method to solve the environmental pollution caused by BSS, and provides a new way for the potential utilization of BSS in edible fungi cultivation.