SpectraX: A Straightforward Tool for Principal Component Analysis-Based Spectral Analysis.

The analysis of complex spectra is an important component of direct/ambient mass spectrometry (MS) applications such as natural product screening. Unlike chromatography-based metabolomics or proteomics approaches, which rely on software and algorithms, the work of spectral screening is mostly performed manually in the initial stages of research and relies heavily on the experience of the analyst. As a result, throughput and spectral screening reliability are problematic when dealing with large amounts of data. Here, we present SpectraX, a MATLAB-based application, which can analyze MS spectra and quickly locate m/z features from them. Principal component analysis (PCA) is used to analyze the data set, and scoring plots are presented to help in understanding the clustering of data. The algorithm uses mass to charge (m/z) features to produce a list of potential natural products.

Hyperspectral Visualization-Based Mass Spectrometry Imaging by LMJ-SSP: A Novel Strategy for Rapid Natural Product Profiling in Bacteria.

Mass spectrometry imaging (MSI) has been widely used to discover natural products (NPs) from underexplored microbiological sources. However, the technique is limited by incompatibility with complicated/uneven surface topography and labor-intensive sample preparation, as well as lengthy compound profiling procedures. Here, liquid micro-junction surface sampling probe (LMJ-SSP)-based MSI is used for rapid profiling of natural products from Gram-negative marine bacteria Pseudoalteromonas on nutrient agar media without any sample preparation. A conductance-based autosampling platform with 1 mm spatial resolution and an innovative multivariant analysis-driven method was used to create one hyperspectral image for the sampling area. NP discovery requires general spatial correlation between m/z and colony location but not highly precise spatial resolution. The hyperspectral image was used to annotate different m/z by straightforward color differences without the need to directly interrogate the spectra. To demonstrate the utility of our approach, the rapid analysis of Pseudoalteromonas rubra DSM6842, Pseudoalteromonas tunicata DSM14096, Pseudoalteromonas piscicida JCM20779, and Pseudoalteromonas elyakovii ATCC700519 cultures was directly performed on Agar. Various natural products, including prodiginine and tambjamine analogues, were quickly identified from the hyperspectral image, and the dynamic extracellular environment was shown with compound heatmaps. Hyperspectral visualization-based MSI is an efficient and sensitive strategy for direct and rapid natural product profiling from different Pseudoalteromonas strains.

Crystal structure of (S)-sec-butyl-ammonium l-tartrate monohydrate.

The title hydrated mol-ecular salt, C4H12N+·C4H5O6-·H2O, was prepared by deprotonation of enanti-opure l-tartaric acid with racemic sec-butyl-amine in water. Only one enanti-omer was observed crystallographically, resulting from the combination of (S)-sec-butyl-amine with l-tartaric acid. The sec-butyl-ammonium moiety is disordered over two conformations related by rotation around the CH-CH2 bond; the refined occupancy ratio is 0.68 (1):0.32 (1). In the crystal, mol-ecules are linked through a network of O-H⋯O and N-H⋯O hydrogen-bonding inter-actions, between the ammonium H atoms, the tartrate hy-droxy H atoms, and the inter-stitial water, forming a three-dimensional supra-molecular structure.