Screening of cellulose-degrading yeast and evaluation of its potential for degradation of coconut oil cake

A simple three-dimensional microfluidic platform for studying chemotaxis and cell sorting

Microbial chemotaxis plays a key role in a diversity of biological and ecological processes. Although microfluidics-based assays have been applied to investigate bacterial chemotaxis, retrieving chemotactic cells off-chip based on their dynamic chemotactic responses remains limited. Here, we present a simple three-dimensional microfluidic platform capable of programmable delivery of solutions, maintaining static, stable gradients for over 20 hours, followed by active sorting and retrieval of bacteria based on their chemotactic phenotypes. Using this platform, we revealed the swimming features of individual E. coli cells in response to chemoattractant and observed rapid bacterial adaptation to the gradients. Furthermore, the robust performance of the platform allowed us to investigate complex natural microbial communities. Exemplified by sorting bacteria towards soluble cellulose and lignin compounds, we found only a small percentage (<20%) of chemotactic bacteria from a leaf mould microbiota exhibited cellulolytic or lignin-degradation abilities. These findings highlight that chemotaxis does not always align with degradation abilities. Interestingly, a new Erwinia aphidicola strain was discovered with substantial cellulose degradation capabilities. These results illustrate the strong potential of this microfluidic platform for investigating broad processes involving bacterial chemotaxis and for discovering functional microbes.

Characteristic of new Phaffia rhodozyma yeast strains isolated from birch slime fluxes in Poland

Three new strains of Phaffia rhodozyma yeast have recently been isolated in Poland. The aim of this study was to phenotypically characterize these strains and to compare them with the properties of the reference strain. The potential for carotenoid biosynthesis in these strains was also determined, depending on temperature, carbon, and nitrogen sources in the medium. Phaffia rhodozyma yeasts were also identified by MALDI-TOF MS. There were minor differences in cell morphology among the strains. All strains reproduced asexually by budding and formed spherical chlamydospores. No ability for sexual reproduction was observed. Physiological tests showed minor variations between the reference strain and the isolates, likely due to the geographical specificity of the habitat from which they were originally isolated. Analysis of protein spectra showed that the tested yeast isolates had seven common peaks of different intensities, with masses at 2200, 2369, 3213, 3628, 3776, 3921, and 4710 m/z. Moreover, additional strain-dependent spectra were found. The amount of synthesized carotenoids varied with the carbon and nitrogen sources used, as well as the temperature. The best producer of carotenoids was the P. rhodozyma CMIFS 102 isolate.

Identification of Cellulose-Degrading Bacteria and Assessment of Their Potential Value for the Production of Bioethanol from Coconut Oil Cake Waste

Bioconversion of lignocellulosic biomass is a highly promising alternative to rapidly reduce reliance on fossil fuels and greenhouse gas emissions. However, the use of lignocellulosic biomass is limited by the challenges of efficient degradation strategies. Given this need, Bacillus tropicus (B. tropicus) with cellulose degradation ability was isolated and screened from rotten dahlia. The strain efficiently utilized coconut oil cake (COC) to secrete 167.3 U/mL of cellulase activity. Electron microscopy results showed significant changes in the structure and properties of cellulose after treatment with B. tropicus, which increased the surface accessibility and the efficiency of the hydrolysis process. The functional group modification observed by Fourier transform infrared spectroscopy indicated the successful depolymerization of COC. The X-ray diffraction pattern showed that the crystallinity index increased from 44.8% to 48.2% due to the hydrolysis of the amorphous region in COC. The results of colorimetry also reveal an efficient hydrolysis process. A co-culture of B. tropicus and Saccharomyces cerevisiae was used to produce ethanol from COC waste, and the maximum ethanol yield was 4.2 g/L. The results of this work show that B. tropicus can be used to prepare biotechnology value-added products such as biofuels from lignocellulosic biomass, suggesting promising utility in biotechnology applications.