Multiple fluorescence labeling and two dimensional FTIR-13C NMR heterospectral correlation spectroscopy to characterize extracellular polymeric substances in biofilms produced during composting.

Knowledge on the structure and function of extracellular polymeric substances (EPS) in biofilms is essential for understanding biodegradation processes. Herein, a novel method based on multiple fluorescence labeling and two-dimensional (2D) FTIR-(13)C NMR heterospectral correlation spectroscopy was developed to gain insight on the composition, architecture, and function of EPS in biofilms during composting. Compared to other environmental biofilms, biofilms in the thermophilic (>55 °C) and cooling (mature) stage of composting have distinct characteristics. The results of multiple fluorescence labeling demonstrated that biofilms were distributed in clusters during the thermophilic stage (day 14), and dead cells were detected. In the mature stage (day 26), the biofilm formed a continuous layer with a thickness of approximately 20-100 µm around the compost, and recolonization of cells at the surface of the compost was easily observed. Through 2D FTIR-(13)C NMR correlation heterospectral spectroscopy, the following trend in the ease of the degradation of organic compounds was observed: heteropolysaccharides > cellulose > amide I in proteins. And proteins and cellulose showed significantly more degradation than heteropolysaccharides. In summary, the combination of multiple fluorescence labeling and 2D correlation spectroscopy is a promising approach for the characterization of EPS in biofilms.

[Studies on the changes in rice straw composition in relay treatment of chemical-microbial process by FTIR spectroscopy].

Direct burning of crop straw in the field has given or is giving rise to a serious pollution of atmosphere. The difficult decomposing of the crop straw by soil microorganisms is one of the reasons the crop straw is not popularly used in agriculture. Fourier transform infrared spectroscopy (FTIR) was used to study the changes in straw composition during the relay treatment of chemical-microbial process. The results showed that the method of FTIR spectra could indicate the changes in straw composition during the treatment processes. After the relay treatment of chemical-microbial process, the contents of cellulose, semi-cellulose, and silicon, and C/N ratio were decreased significantly, while the water soluble substances were increased, which was in accordance with the results of chemical analysis. The method to treat crop straw proposed in this paper could provide a practicable way in agricultural utilization of crop straw.

Fate of biopolymers during rapeseed meal and wheat bran composting as studied by two-dimensional correlation spectroscopy in combination with multiple fluorescence labeling techniques.

Detailed knowledge of the molecular events during composting is important in improving the efficiency of this process. By combining two-dimensional Fourier transform infrared (FTIR) correlation spectroscopy and multiple fluorescent labeling, it was possible to study the degradation of biopolymers during rapeseed meal and wheat bran composting. Two-dimensional FTIR correlation spectroscopy provided structural information and was used to deconvolute overlapping bands found in the compost FTIR spectra. The degradation of biopolymers in rapeseed meal and wheat bran composts followed the sequence: cellulose, heteropolysaccharides, and proteins. Fluorescent labeling suggested that cellulose formed an intact network-like structure and the other biopolymers were embedded in the core of this structure. The sequence of degradation of biopolymers during composting was related to their distribution patterns.