Identification of Soil Microbes Capable of Utilizing Cellobiosan

Approximately 100 million tons of anhydrosugars, such as levoglucosan and cellobiosan, are produced through biomass burning every year. These sugars are also produced through fast pyrolysis, the controlled thermal depolymerization of biomass. While the microbial pathways associated with levoglucosan utilization have been characterized, there is little known about cellobiosan utilization. Here we describe the isolation and characterization of six cellobiosan-utilizing microbes from soil samples. Each of these organisms is capable of using both cellobiosan and levoglucosan as sole carbon source, though both minimal and rich media cellobiosan supported significantly higher biomass production than levoglucosan. Ribosomal sequencing was used to identify the closest reported match for these organisms:Sphingobacterium multivorum, Acinetobacter oleivorans JC3-1, Enterobacter sp SJZ-6, andMicrobacterium sps FXJ8.207 and 203 and a fungal species Cryptococcus sp. The commercially-acquired Enterobacter cloacae DSM 16657 showed growth on levoglucosan and cellobiosan, supporting our isolate identification. Analysis of an existing database of 16S rRNA amplicons from Iowa soil samples confirmed the representation of our five bacterial isolates and four previously-reported levoglucosan-utilizing bacterial isolates in other soil samples and provided insight into their population distributions. Phylogenetic analysis of the 16S rRNA and 18S rRNA of strains previously reported to utilize levoglucosan and our newfound isolates showed that the organisms isolated in this study are distinct from previously described anhydrosugar-utilizing microbial species

Research on Distinguishing Fish Meal Quality Using Different Characteristic Parameters Based on Electronic Nose Technology

In this paper, a portable electronic nose, that was independently developed, was employed to detect and classify a fish meal of different qualities. SPME-GC-MS (solid phase microextraction gas chromatography mass spectrometry) analysis of fish meal was presented. Due to the large amount of data of the original features detected by the electronic nose, a reasonable selection of the original features was necessary before processing, so as to reduce the dimension. The integral value, wavelet energy value, maximum gradient value, average differential value, relation steady-state response average value and variance value were selected as six different characteristic parameters, to study fish meal samples with different storage time grades. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA), and five recognition modes, which included the multilayer perceptron neural network classification method, random forest classification method, k nearest neighbor algorithm, support vector machine algorithm, and Bayesian classification method, were employed for the classification. The result showed that the RF classification method had the highest accuracy rate for the classification algorithm. The highest accuracy rate for distinguishing fish meal samples with different qualities was achieved using the integral value, stable value, and average differential value. The lowest accuracy rate for distinguishing fish meal samples with different qualities was achieved using the maximum gradient value. This finding shows that the electronic nose can identify fish meal samples with different storage times

Study of AlGaN/GaN Vertical Superjunction HEMT for Improvement of Breakdown Voltage and Specific On-Resistance

A GaN-based vertical superjunction high electron mobility transistor (SJ HEMT) with a composite structure (CS-SJ HEMT) is proposed and analyzed by Silvaco TCAD to improve the breakdown voltage and specific on-resistance (RonA). In this paper, CS-SJ HEMT is compared with SJ HEMT with traditional structure (TS-SJ HEMT), SJ HEMT with only particular doping pillars (DP-SJ HEMT) and SJ HEMT with only special P-gate (SP-SJ HEMT). The particular doping pillars mean the doping concentration of n-pillar increases with a gradient from top to bottom, and the concentration of p-pillar is the same as the middle of n-pillar, which reduces the RonA by only 4%. The special P-GaN cap layer can reduce the RonA by 10%, and it can even increase the on-state current in the saturation region. The CS-SJ HEMT combines both doping pillars and special P-gate structures, and the RonA can be reduced by 14%. By the optimized design, the RonA can be reduced by 30% with BV = 2580 V, or the RonA can be reduced by 21% with BV = 2720 V. These results show that the composite structure of SJ HEMT contributes to improving the BV and RonA and propose a useful approach for improving the vertical HEMTs

Identification of Soil Microbes Capable of Utilizing Cellobiosan

Approximately 100 million tons of anhydrosugars, such as levoglucosan and cellobiosan, are produced through biomass burning every year. These sugars are also produced through fast pyrolysis, the controlled thermal depolymerization of biomass. While the microbial pathways associated with levoglucosan utilization have been characterized, there is little known about cellobiosan utilization. Here we describe the isolation and characterization of six cellobiosan-utilizing microbes from soil samples. Each of these organisms is capable of using both cellobiosan and levoglucosan as sole carbon source, though both minimal and rich media cellobiosan supported significantly higher biomass production than levoglucosan. Ribosomal sequencing was used to identify the closest reported match for these organisms:Sphingobacterium multivorum, Acinetobacter oleivorans JC3-1, Enterobacter sp SJZ-6, andMicrobacterium sps FXJ8.207 and 203 and a fungal species Cryptococcus sp. The commercially-acquired Enterobacter cloacae DSM 16657 showed growth on levoglucosan and cellobiosan, supporting our isolate identification. Analysis of an existing database of 16S rRNA amplicons from Iowa soil samples confirmed the representation of our five bacterial isolates and four previously-reported levoglucosan-utilizing bacterial isolates in other soil samples and provided insight into their population distributions. Phylogenetic analysis of the 16S rRNA and 18S rRNA of strains previously reported to utilize levoglucosan and our newfound isolates showed that the organisms isolated in this study are distinct from previously described anhydrosugar-utilizing microbial species.This article is from PLoS ONE 11(2): e0149336. doi:10.1371/journal.pone.0149336. Posted with permission.</p

16S rRNA gene-based identification of soil isolates and population analysis of 16S rRNA gene for five cellobiosan-utilizing bacterial isolates and four levoglucosan-utilizing bacterial isolates based on sequences of Iowa COBS soil microbial community.

<p>Isolates S1, S2, S3, S4, S5, and F6 utilize cellobiosan. Isolates 1, 2, 3 and 4 utilization levogluocsan. OTU: Operational taxonomic unit, here is defined as genes sharing 97% sequence similarity in the COBS dataset. Abundance: the relative abundance of OTU within COBS dataset.</p

Strains within the NCBI nr database sharing similarity to the isolates studied here.

<p>Strains were selected based on their reported ability to utilize levoglucosan. <i>Bacillus horikoshii</i>, <i>Bacillus korlensis</i> 1 and 2, and <i>Bacillus</i> sp 5138, were originally named bacterium levoglucosan 1, 2, 8, and 10, respectively, and were putatively identified in this work (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0149336#pone.0149336.t001" target="_blank">Table 1</a>).</p

Phylogenetic analysis.

<p>A maximum likelihood reconstruction of the phylogenetic analysis of 16S rRNA genes of our isolates (blue boxes) and of selected type strains. Isolates are more diverse than previously reported levogluosan-utilizing isolates (red box). The closest relative to isolates by 16S rRNA gene similarity in the RDP database is shown in parentheses.</p