More and more studies are dedicated to termites and their symbionts, to better understand how they efficiently produce energy from lignocellulose. In that context, a powerful analytical method was developed to perform the detection, separation and identification of compounds in the 1 µL fluid volume of the gut of the termite Reticulitermes flavipes. Comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (TOFMS) was tested with three different column combinations: (1) low-polar/mid-polar; (2) polar/low-polar and (3) mid-polar/low-polar. The column set (3) offered the best separation and was chosen for further analysis and comparison study. Metabolites were detected in the samples, including amino acids, sugars, amines and organic acids. Samples collected from termites fed for 30 days on Avicel cellulose or xylan powder diets were analyzed and compared with the wood diet. Principal component analysis (PCA) of metabolite profiles demonstrated a separation of different clusters corresponding to the three different diets, with a similar trend for diets containing cellulose. The Analysis of variance (ANOVA) (one way-ANOVA and Tukey’s test) was used to compare compound levels between these three different diets. Significant differences were observed, including higher levels of aromatic derivatives in the wood diet and higher levels of sugar alcohols in the xylan diet. A higher accumulation of uric acid was observed with the artificial diets (cellulose and xylan), likely to be related to the nitrogen deficiency. The present study highlighted the capability of adaptation of the termite system to non-optimal carbon sources and the subsequent modification of the metabolite profile. These results demonstrate the potential interest to investigate metabolite profiling with state-of-the-art separation science tools, in order to extract information that could be integrated with other omics data to provide more insight into the termite-symbiont digestion system. Full article

Hindgut homogenates of the termite Reticulitermes santonensis were incubated with carboxymethyl cellulose (CMC), crystalline celluloses or xylan substrates. Hydrolysates were analyzed with matrix-assisted laser desorption/ionization coupled to time-of-flight mass spectrometry (MALDI-TOF MS). The method was first set up using acid hydrolysis analysis to characterize non-enzymatic profiles. Commercial enzymes of Trichoderma reesei or T. longibrachiatum were also tested to validate the enzymatic hydrolysis analysis. For CMC hydrolysis, data processing and visual display were optimized to obtain comprehensive profiles and allow rapid comparison and evaluation of enzymatic selectivity, according to the number of substituents of each hydrolysis product. Oligosaccharides with degrees of polymerization (DPs) ranging from three to 12 were measured from CMC and the enzymatic selectivity was demonstrated. Neutral and acidic xylo-oligosaccharides with DPs ranging from three to 11 were measured from xylan substrate. These results are of interest for lignocellulose biomass valorization and demonstrated the potential of termites and their symbiotic microbiota as a source of interesting enzymes for oligosaccharides production. Full article

Many studies have evidenced the main role of lipids in physiological and also pathological processes such as cancer, diabetes or neurodegenerative diseases. The identification and the in situ localization of specific low-abundant lipid species involved in cancer biology are still challenging for both fundamental studies and lipid marker discovery. In this paper, we report the identification and the localization of specific isobaric minor phospholipids in human breast cancer xenografts by FTICR MALDI imaging supported by histochemistry. These potential candidates can be further confirmed by liquid chromatography coupled with electrospray mass spectrometry (LC-ESI-MS) after extraction from the region of interest defined by MALDI imaging. Finally, this study highlights the importance of characterizing the heterogeneous distribution of low-abundant lipid species, relevant in complex histological samples for biological purposes. Full article