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1.  Involvement of Two Latex-Clearing Proteins during Rubber Degradation and Insights into the Subsequent Degradation Pathway Revealed by the Genome Sequence of Gordonia polyisoprenivorans Strain VH2 
The increasing production of synthetic and natural poly(cis-1,4-isoprene) rubber leads to huge challenges in waste management. Only a few bacteria are known to degrade rubber, and little is known about the mechanism of microbial rubber degradation. The genome of Gordonia polyisoprenivorans strain VH2, which is one of the most effective rubber-degrading bacteria, was sequenced and annotated to elucidate the degradation pathway and other features of this actinomycete. The genome consists of a circular chromosome of 5,669,805 bp and a circular plasmid of 174,494 bp with average GC contents of 67.0% and 65.7%, respectively. It contains 5,110 putative protein-coding sequences, including many candidate genes responsible for rubber degradation and other biotechnically relevant pathways. Furthermore, we detected two homologues of a latex-clearing protein, which is supposed to be a key enzyme in rubber degradation. The deletion of these two genes for the first time revealed clear evidence that latex-clearing protein is essential for the microbial utilization of rubber. Based on the genome sequence, we predict a pathway for the microbial degradation of rubber which is supported by previous and current data on transposon mutagenesis, deletion mutants, applied comparative genomics, and literature search.
doi:10.1128/AEM.07969-11
PMCID: PMC3318801  PMID: 22327575
2.  Novel Family of Carbohydrate-Binding Modules Revealed by the Genome Sequence of Spirochaeta thermophila DSM 6192 ▿ †  
Applied and Environmental Microbiology  2011;77(15):5483-5489.
Spirochaeta thermophila is a thermophilic, free-living, and cellulolytic anaerobe. The genome sequence data for this organism have revealed a high density of genes encoding enzymes from more than 30 glycoside hydrolase (GH) families and a noncellulosomal enzyme system for (hemi)cellulose degradation. Functional screening of a fosmid library whose inserts were mapped on the S. thermophila genome sequence allowed the functional annotation of numerous GH open reading frames (ORFs). Seven different GH ORFs from the S. thermophila DSM 6192 genome, all putative β-glycanase ORFs according to sequence similarity analysis, contained a highly conserved novel GH-associated module of unknown function at their C terminus. Four of these GH enzymes were experimentally verified as xylanase, β-glucanase, β-glucanase/carboxymethylcellulase (CMCase), and CMCase. Binding experiments performed with the recombinantly expressed and purified GH-associated module showed that it represents a new carbohydrate-binding module (CBM) that binds to microcrystalline cellulose and is highly specific for this substrate. In the course of this work, the new CBM type was only detected in Spirochaeta, but recently we found sequences with detectable similarity to the module in the draft genomes of Cytophaga fermentans and Mahella australiensis, both of which are phylogenetically very distant from S. thermophila and noncellulolytic, yet inhabit similar environments. This suggests a possibly broad distribution of the module in nature.
doi:10.1128/AEM.00523-11
PMCID: PMC3147429  PMID: 21685171
3.  Formation of volatiles and fattyacids of therapeutic importance in the probiotic Lactobacillus plantarum LPcfr adapted to resist GIT conditions 
Probiotics are the microorganisms that impart therapeutic effect and promote health by preventing various diseases. In the present work, the volatile compounds were studied in the native isolate Lactobacillus plantarum (LP) and after adaptation to resist gastro intestinal tract (GIT) conditions, which was coded as LPcfr. A number of therapeutically important compounds were present in LPcfr like butanediol (2.5%) and propionic acid (2.8%), which were not found in LP. Hexadecane (3%), butanoic acid (2%), dodecanal (2%), hexanal (7.5%), hexadecanoic acid (4%) and heptanal (6%) were found in higher concentrations in LPcfr as compared to the parent strain LP. Production of oleic acid (LP-19.2%; LPcfr -33.5%), known for reducing blood cholesterol and linoleic acid (LPcfr 2.3%), and a conjugated fatty acid known as a novel beneficial functional lipid was noticed. Linoleic acid was absent in LP. These important fatty acids were found in larger quantities in the probiotic adapted culture strain LPcfr as compared to the parent strain LP.
doi:10.1007/s13197-010-0110-5
PMCID: PMC3551077  PMID: 23572725
Volatiles; Fattyacids; Lactobacillus plantarum
4.  Characterization of Plasmid pPO1 from the Hyperacidophile Picrophilus oshimae 
Archaea  2011;2011:723604.
Picrophilus oshimae and Picrophilus torridus are free-living, moderately thermophilic and acidophilic organisms from the lineage of Euryarchaeota. With a pH optimum of growth at pH 0.7 and the ability to even withstand molar concentrations of sulphuric acid, these organisms represent the most extreme acidophiles known. So far, nothing is known about plasmid biology in these hyperacidophiles. Also, there are no genetic tools available for this genus. We have mobilized the 7.6 Kbp plasmid from P. oshimae in E. coli by introducing origin-containing transposons and described the plasmid in terms of its nucleotide sequence, copy number in the native host, mode of replication, and transcriptional start sites of the encoded ORFs. Plasmid pPO1 may encode a restriction/modification system in addition to its replication functions. The information gained from the pPO1 plasmid may prove useful in developing a cloning system for this group of extreme acidophiles.
doi:10.1155/2011/723604
PMCID: PMC3177234  PMID: 21941462
5.  Genomic analysis reveals Lactobacillus sanfranciscensis as stable element in traditional sourdoughs 
Microbial Cell Factories  2011;10(Suppl 1):S6.
Sourdough has played a significant role in human nutrition and culture for thousands of years and is still of eminent importance for human diet and the bakery industry. Lactobacillus sanfranciscensis is the predominant key bacterium in traditionally fermented sourdoughs.
The genome of L. sanfranciscensis TMW 1.1304 isolated from an industrial sourdough fermentation was sequenced with a combined Sanger/454-pyrosequencing approach followed by gap closing by walking on fosmids. The sequencing data revealed a circular chromosomal sequence of 1,298,316 bp and two additional plasmids, pLS1 and pLS2, with sizes of 58,739 bp and 18,715 bp, which are predicted to encode 1,437, 63 and 19 orfs, respectively. The overall GC content of the chromosome is 34.71%. Several specific features appear to contribute to the ability of L. sanfranciscensis to outcompete other bacteria in the fermentation. L. sanfranciscensis contains the smallest genome within the lactobacilli and the highest density of ribosomal RNA operons per Mbp genome among all known genomes of free-living bacteria, which is important for the rapid growth characteristics of the organism. A high frequency of gene inactivation and elimination indicates a process of reductive evolution. The biosynthetic capacity for amino acids scarcely availably in cereals and exopolysaccharides reveal the molecular basis for an autochtonous sourdough organism with potential for further exploitation in functional foods. The presence of two CRISPR/cas loci versus a high number of transposable elements suggests recalcitrance to gene intrusion and high intrinsic genome plasticity.
doi:10.1186/1475-2859-10-S1-S6
PMCID: PMC3231932  PMID: 21995419
6.  Genome Sequence of the Polysaccharide-Degrading, Thermophilic Anaerobe Spirochaeta thermophila DSM 6192▿  
Journal of Bacteriology  2010;192(24):6492-6493.
Spirochaeta thermophila is a thermophilic, free-living anaerobe that is able to degrade various α- and β-linked sugar polymers, including cellulose. We report here the complete genome sequence of S. thermophila DSM 6192, which is the first genome sequence of a thermophilic, free-living member of the Spirochaetes phylum. The genome data reveal a high density of genes encoding enzymes from more than 30 glycoside hydrolase families, a noncellulosomal enzyme system for (hemi)cellulose degradation, and indicate the presence of a novel carbohydrate-binding module.
doi:10.1128/JB.01023-10
PMCID: PMC3008529  PMID: 20935097
7.  Hyperthermostable acetyl xylan esterase 
Microbial biotechnology  2009;3(1):84-92.
Summary
An esterase which is encoded within a Thermotoga maritima chromosomal gene cluster for xylan degradation and utilization was characterized after heterologous expression of the corresponding gene in Escherichia coli and purification of the enzyme. The enzyme, designated AxeA, shares amino acid sequence similarity and its broad substrate specificity with the acetyl xylan esterase from Bacillus pumilus, the cephalosporin C deacetylase from Bacillus subtilis, and other (putative) esterases, allowing its classification as a member of carbohydrate esterase family 7. The recombinant enzyme displayed activity with p‐nitrophenyl‐acetate as well as with various acetylated sugar substrates such as glucose penta‐acetate, acetylated oat spelts xylan and DMSO (dimethyl sulfoxide)‐extracted beechwood xylan, and with cephalosporin C. Thermotoga maritimaAxeA represents the most thermostable acetyl xylan esterase known to date. In a 10 min assay at its optimum pH of 6.5 the enzyme's activity peaked at 90°C. The inactivation half‐life of AxeA at a protein concentration of 0.3 µg µl−1 in the absence of substrate was about 13 h at 98°C and about 67 h at 90°C. Differential scanning calorimetry analysis of the thermal stability of AxeA corroborated its extreme heat resistance. A multi‐phasic unfolding behaviour was found, with two apparent exothermic peaks at approximately 100–104°C and 107.5°C. In accordance with the crystal structure, gel filtration analysis at ambient temperature revealed that the enzyme has as a homohexameric oligomerization state, but a dimeric form was also found.
doi:10.1111/j.1751-7915.2009.00150.x
PMCID: PMC3815950  PMID: 21255309
8.  Molecular and Biochemical Characterization of α-Glucosidase and α-Mannosidase and Their Clustered Genes from the Thermoacidophilic Archaeon Picrophilus torridus†  
Journal of Bacteriology  2006;188(20):7123-7131.
The genes encoding a putative α-glucosidase (aglA) and an α-mannosidase (manA) appear to be physically clustered in the genome of the extreme acidophile Picrophilus torridus, a situation not found previously in any other organism possessing aglA or manA homologs. While archaeal α-glucosidases have been described, no α-mannosidase enzymes from the archaeal kingdom have been reported previously. Transcription start site mapping and Northern blot analysis revealed that despite their colinear orientation and the small intergenic space, the genes are independently transcribed, both producing leaderless mRNA. aglA and manA were cloned and overexpressed in Escherichia coli, and the purified recombinant enzymes were characterized with respect to their physicochemical and biochemical properties. AglA displayed strict substrate specificity and hydrolyzed maltose, as well as longer α-1,4-linked maltooligosaccharides. ManA, on the other hand, hydrolyzed all possible linkage types of α-glycosidically linked mannose disaccharides and was able to hydrolyze α3,α6-mannopentaose, which represents the core structure of many triantennary N-linked carbohydrates in glycoproteins. The probable physiological role of the two enzymes in the utilization of exogenous glycoproteins and/or in the turnover of the organism's own glycoproteins is discussed.
doi:10.1128/JB.00757-06
PMCID: PMC1636218  PMID: 17015651

Results 1-8 (8)