Capillary ion chromatography–mass spectrometry for simultaneous determination of glucosylglycerol and sucrose in intracellular extracts of cyanobacteria

Metabolite profiling of plant growth promoting cyanobacteria-Anabaena laxa and Calothrix elenkinii, using untargeted metabolomics

The metabolite profiles of two plant growth promoting cyanobacteria-Anabaena laxa and Calothrix elenkinii, which serve as promising biofertilizers, and biocontrol agents were generated to investigate their agriculturally beneficial activities. Preliminary biochemical analyses, in terms of total chlorophyll, total proteins, and IAA were highest at 14 days after inoculation (DAI). In A. laxa 20-25% higher values of reducing sugars, than C. elenkinii at both 14 and 21 DAI were recorded. Carbon and nitrogen assimilating enzyme activities-phosphoenol pyruvate carboxylase (PEPC), carbonic anhydrase (CA), and glutamine synthetase (GS) were highest at 14 DAI, albeit, nitrate reductase (NR) activity was higher by 0.73-0.84-fold at 21 DAI. Untargeted GC-MS (Gas chromatography-Mass spectrometric) analysis of metabolite profiles of 21d-old cyanobacterial cultures and characterization using NIST mass spectral library illustrated that A. laxa recorded highest number of metabolite hits in three chemical classes namely amino acid and peptides, nucleotides, nucleosides and analogues, besides other organic compounds. Based on the pathway analysis of identified metabolites, both A. laxa, and C. elenkinii were enriched in metabolites involved in aminoacyl-tRNA biosynthesis, and amino acid metabolism pathways, particularly lactose and glutamic acid, which are important players in plant-microbe interactions. Correlation-based metabolite network illustrated distinct and significant differences in the metabolic machinery of A. laxa and C. elenkinii, highlighting their novel identity and enrichment in C-N rich metabolites, as factors underlying their plant growth and soil fertility enhancing attributes, which make them valuable as inoculants.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03902-7.

Molecular Level Sucrose Quantification: A Critical Review

Sucrose is a primary metabolite in plants, a source of energy, a source of carbon atoms for growth and development, and a regulator of biochemical processes. Most of the traditional analytical chemistry methods for sucrose quantification in plants require sample treatment (with consequent tissue destruction) and complex facilities, that do not allow real-time sucrose quantification at ultra-low concentrations (nM to pM range) under in vivo conditions, limiting our understanding of sucrose roles in plant physiology across different plant tissues and cellular compartments. Some of the above-mentioned problems may be circumvented with the use of bio-compatible ligands for molecular recognition of sucrose. Nevertheless, problems such as the signal-noise ratio, stability, and selectivity are some of the main challenges limiting the use of molecular recognition methods for the in vivo quantification of sucrose. In this review, we provide a critical analysis of the existing analytical chemistry tools, biosensors, and synthetic ligands, for sucrose quantification and discuss the most promising paths to improve upon its limits of detection. Our goal is to highlight the criteria design need for real-time, in vivo, highly sensitive and selective sucrose sensing capabilities to enable further our understanding of living organisms, the development of new plant breeding strategies for increased crop productivity and sustainability, and ultimately to contribute to the overarching need for food security.

Anion Exchange Chromatography Coupled to Electrospray-Mass Spectrometry: An Efficient Tool for Food, Environment, and Biological Analysis

For over 50 years, ion chromatography has been demonstrated to be a successful technique used to quantify a wide range of ions and ionizable compounds, either organic or inorganic, in various matrices using conductimetric or electrochemical detection. It was only since 1996 that ion chromatography was coupled to electrospray-mass spectrometry, opening the field to new applications in complex matrices and the detection of compounds at trace levels. This review covers the recent developments of ion exchange chromatography and mass spectrometry. It focuses on the choice of mobile phases, column geometry, suppressors, make-up solvents and type of ionization sources reported in the literature. A brief overview of a large range of applications in food analysis, environmental analysis and bioanalysis is presented, and performances are discussed.

Simultaneous Detection of Anions and Carbohydrates in Cyanobacteria by Two-Dimensional Ion Chromatography

BACKGROUND

The simultaneous analysis of several anions and carbohydrates by one-dimensional chromatography with a single detector is often complicated by the presence of overlapping peaks. To overcome this problem, analytes are usually analyzed separately making analysis long and tedious.

OBJECTIVE

A method combining two-dimensional ion chromatography (2D-IC) and valve switching was developed for the simultaneous determination of anions (F-, Cl-, NO2-, SO42-, NO3-, and PO43-) and carbohydrates (glycerin, glucosyl glycerol, trehalose, mannose, glucose, galactose, fructose, ribose, and sucrose) in cyanobacteria.

METHOD

Interfering color compounds were removed by first passing the sample through graphitized carbon solid phase extraction (SPE) cartridges. Samples were applied to an AS11-HC column, which was used to separate the anions followed by quantification using a conductance detector. Carbohydrates eluted from the AS11-HC column were trapped and separated on a MA1 column and simultaneously quantified using electrochemical detection in the second dimension with valve switching.

RESULTS

The following parameters were established: LOD, 0.001-0.030 (mg/L); LOQ, 0.001-0.010 (mg/L); linearity (R2), 0.9940; repeatability, 0.39-3.02%; and spiked recovery, 90.1-107%.

CONCLUSIONS

The proposed method is adequately linear, accurate, and repeatable. The 2D-IC method provides fast, high-resolution, and completely automated procedure for the simultaneous determination of anions and carbohydrates without co-elution compared to the 1D ion chromatography method. This study provides application perspectives for use in biotechnology and other research fields.

HIGHLIGHTS

An accurate and effective 2D-IC method was developed for determining anions and carbohydrates in cyanobacteria. The method includes pre-treating samples with graphitized carbon SPE cartridges.

Determination of Intracellular Osmolytes in Cyanobacterial Cells

Most of the cyanobacteria accumulate osmolytes including sucrose, glucosylglycerol, in their cells in response to salt stress. Here we describe a protocol of our laboratory for extraction and quantification of cyanobacterial intracellular sucrose and glucosylglycerol. We have confirmed this protocol was applicable to at least four kinds of cyanobacteria, filamentous cyanobacterium Anabaena sp. PCC 7120, unicellular cyanobacterium Synechocystis sp. PCC 6803, Synechococcus elongatus PCC 7942 and halotolerant unicellular cyanobacterium Synechococcus sp. PCC 7002.