Fig 1.
Overview of the anhydrosugar cycle and its relevance to the production of biorenewable fuels and chemicals.
Images are from creative commons.
Table 1.
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.
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.
Fig 2.
Isolation of microbes capable of using cellobiosan as sole carbon source.
(A) Aqueous soil extract, (B) Soil. Pure cultures of S1-S5 and F6. All plates consisted of M9 with 2.0 wt% cellobiosan and were grown at 30°C for 24 hours.
Fig 3.
Microbial growth on cellobiosan.
(A) Enterobacter DSM16657, (B) our soil isolates on M9 minimal medium with 2.0 wt% cellobiosan at 30°C, 200 rpm for 24 hours. Data is the average of 3 biological replicates, with error bars showing one standard deviation.
Fig 4.
Growth of our isolates on levoglucosan and cellobiosan.
Growth of isolates in M9 with 2.0 wt% levoglucosan (M9-LG), M9 with 2.0 wt% cellobiosan (M9-C), LB with no supplemental carbon (LB), LB with 2.0 wt% levoglucosan (LB-LG), and LB with 2.0 wt% cellobiosan (LB-C). Note that M9 is a mineral salts media and a supplemental carbon source must be provided to support microbial growth. Thus, M9 with no supplemental carbon is not feasible. Isolates were grown for 24 hours at 30°C, 200 rpm. Data is the average of three biological replicates and error bars indicate the standard deviation. P values were < 0.01 for all organisms in M9-LG versus M9-C and < 0.05 for all organisms in LB-LG vs. LB-C.
Fig 5.
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.
Table 2.
Strains within the NCBI nr database sharing similarity to the isolates studied here.
Strains were selected based on their reported ability to utilize levoglucosan. Bacillus horikoshii, Bacillus korlensis 1 and 2, and Bacillus sp 5138, were originally named bacterium levoglucosan 1, 2, 8, and 10, respectively, and were putatively identified in this work (Table 1).