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At least 1,189 records · Page 66Linked to original sources
PubMed1997

Microbulbifer hydrolyticus gen. nov., sp. nov., and Marinobacterium georgiense gen. nov., sp. nov., two marine bacteria from a lignin-rich pulp mill waste enrichment community.

Two numerically important bacteria in marine pulp mill effluent enrichment cultures were isolated. These organisms were gram-negative, rod-shaped, strictly aerobic bacteria. Isolate IRE-31T (T = type strain) produced hydrolytic enzymes for the breakdown of cellulose, xylan, chitin, gelatin, and Tween 80. It also utilized a variety of monosaccharides, disaccharides, amino acids, and volatile fatty acids for growth. Isolate KW-40T did not utilize natural polymers, but it could grow on a variety of monosaccharides, disaccharides, alcohols, and amino acids. It also utilized methanol and aromatic compounds. The surfaces of both organisms were covered by blebs and vesicles. 16S rRNA analyses placed both organisms in the gamma-3 subclass of the phylum Proteobacteria. They were related to Oceanospirillum linum, Marinomonas vaga, Pseudomonas putida, and Halomonas elongata, although a close association with any of these bacteria was not found. The guanine-plus-cytosine contents of strain IRE-31T and KW-40T were 57.6 and 54.9 mol%, respectively. On the basis of 16S rRNA sequence and phenotypic characterizations, these isolates were different enough so that they could be considered members of new genera. Thus, the following two new genera and species are proposed: Microbulbifer hydrolyticus, with type strain IRE-31 (= ATCC 700072), and Marinobacterium georgiense, with type strain KW-40 (= ATCC 700074).

Base Composition↗
PubMed1994

Isoenzymes of manganese-dependent peroxidase and laccase produced by the lignin-degrading basidiomycete Ceriporiopsis subvermispora.

The white-rot basidiomycete Ceriporiopsis subvermispora produces two families of ligninolytic enzymes, namely manganese-dependent peroxidases (MnPs) and laccases, when growing in liquid cultures of defined composition. In medium containing 11 p.p.m. of Mn(II), up to seven isoenzymes of MnP and four isoenzymes of laccase were resolved by isoelectrofocusing (IEF), with pI values in the range 4.10-4.60 and 3.45-3.65, respectively. Occasionally, a fifth laccase isoform of pI 4.70 was also detected. In cultures with 25 and 40 p.p.m. of Mn(II), mainly the MnPs with higher pI values are produced. The isoenzyme pattern of MnP is not altered throughout the growth period of the fungus. MnP and laccase are also produced by C. subvermispora when growing on wood chips of Pinus radiata. Highest levels of both enzymes were obtained during the first week of incubation. A second peak of MnP activity was observed during the fourth week, whereas very low levels of laccase were extracted from the chips after the second week of growth. IEF analysis showed that the pI values of these laccases are similar to those of laccases produced in liquid cultures, being in the range 3.45-3.65. In contrast, four isoforms of MnP were resolved during the first week of incubation on wood chips, with pI values of 4.40, 4.17, 4.04 and 3.53. This profile underwent a transition during the second week of growth, at the end of which isoforms of MnP with pI values of 3.53, 3.40, 3.30 and 3.20 were resolved by IEF.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1997

Molecular cloning of 4-coumarate:coenzyme A ligase in loblolly pine and the roles of this enzyme in the biosynthesis of lignin in compression wood.

Two genomic sequences encoding 4-coumarate:coenzyme A ligase (4CL; EC 6.2.1.12) in loblolly pine (Pinus taeda L.) were cloned. Both sequences contained three introns and four exons with identical coding sequences predicting 537 amino acids. Two of the three introns in these two clones were different both in sequence and in length. Sequences of both 4CL clones were found in all nine megagametophyte DNAs tested, providing genetic evidence that these two 4CL genomic sequences are nonallelic genes. Our analyses suggest that there are at least two distinct, intron-containing 4CL genes, at least one of which is transcribed into 4CL mRNA in developing xylem tissue of loblolly pine. The levels of 4CL gene transcription in xylem were influenced by compressional stress, resulting in an elevated 4CL enzyme activity with 4-coumaric acid. 4CL enzyme activity with ferulic acid remained unchanged, whereas with caffeic acid it was significantly inhibited. Exogenously applied trans-cinnamic acid in the protein extracts from normal wood xylem caused inhibition of 4CL activity toward caffeic acid similar to that under compressional stress. The implications of this cinnamic acid-modulated effect on 4CL enzyme activities toward different substrates in regulating monolignol synthesis in xylem under compressional stress are discussed.

Cloning, Molecular↗
PubMed1994

Differential expression of multiple exo-cellobiohydrolase I-like genes in the lignin-degrading fungus Phanerochaete chrysosporium.

The genome of Phanerochaete chrysosporium strain ME446 contains multiple, non-allelic, cellobiohydrolase I (CBHI)-like sequences, at least two of which are expressed in a cellulose-dependent manner. Each of the expressed genes contains two identically positioned introns within its coding region. The lengths and sequences of these introns are different and one is not excised from all transcripts, raising the possibility that subtly different protein products may be expressed from a common gene. Introns are also present upstream of both genes but these differ in number and position, as well as sequence and length. Endoglucanase-like sequences could not be identified and it is suggested that variant CBHI-like proteins may provide endoglucanase activity in this fungus.

Amino Acid Sequence↗
PubMed2006

Identification of cold acclimation-responsive Rhododendron genes for lipid metabolism, membrane transport and lignin biosynthesis: importance of moderately abundant ESTs in genomic studies.

We have previously analysed expressed sequence tags (ESTs) from non-acclimated (NA) and cold-acclimated (CA) Rhododendron leaves, and identified highly abundant complementary DNAs (cDNAs) possibly involved in cold acclimation. A potentially significant, but relatively unexplored, application of these EST data sets is the study of moderately abundant cDNAs, such as those picked only 1-3 times from each Rhododendron EST library containing approximately 430 ESTs. Using statistical tests and Northern blots, we established that the probability of differential expression of moderately abundant cDNAs based on the EST data is, indeed, a reasonably accurate predictor of their 'true' upregulation or downregulation as 11 out of 13 cDNAs (85%) studied fit this criterion. The analyses also revealed four aspects of cold acclimation in Rhododendron leaf tissues. Firstly, the concomitant upregulation of long-chain acyl-coenzyme A (acyl-CoA) synthetase, CTP:cholinephosphate cytidylyltransferase and delta-12 fatty acid desaturase in CA leaf tissues suggests that phospholipid biosynthesis and desaturation are important components of cold hardening in Rhododendron. Secondly, upregulation of plastidic nicotinamide adenine dinucleotide phosphatemalic enzyme (NADP-ME) in CA tissues suggests that malate is an important source of acetyl-CoA used for fatty acid biosynthesis during cold acclimation. Thirdly, down-regulation of plasma membrane intrinsic protein (PIP)2-1 aquaporin and upregulation of gated outward rectifying K+ channel (GORK) in CA tissues may be associated with the protection of overwintering leaves from freeze-induced cellular dehydration. Fourthly, upregulation of coumarate 3-hydroxylase may be associated with cell wall thickening in CA tissues. Physiological implications of these results, which reveal potentially novel regulations of cold acclimation in overwintering woody evergreens, are discussed. This work highlights the importance of also investigating low/moderately abundant ESTs (in addition to highly abundant ones) in genomic studies, in that it offers an effective strategy for identifying stress-related genes, especially when large-scale cDNA sequencing/microarray studies are not possible.

Acclimatization↗
PubMed1979

Enzymic synthesis of lignin precursors. Further studies on cinnamyl-alcohol dehydrogenase from soybean-cell-suspension cultures.

Isoenzyme 2 of cinnamyl-alcohol dehydrogenase from soybean suspension cultures was purified about 3800-fold to apparent homogeneity by an improved purification procedure involving biospecific elution of the enzyme from a NADP+-agarose column. On sodium dodecylsulfate gels the dehydrogenase showed only one protein band with Mr 40 000 +/- 500. The enzyme is strongly inhibited by thiol reagents. Various metal chelators as well as the nonchelating 7,8-benzoquinoline also inhibited enzyme activity. Inhibition by 10 mM 1,10-phenanthroline could be partially reversed by addition of Zn2+. 1,10-Phenanthroline and 7,8-benzoquinoline are non-competitive inhibitors with respect to NADP+. The presence of zinc in the dehydrogenase was proved by atomic absorption spectroscopy and by specific incorporation of 65Zn into the enzyme. In steady-state kinetics inhibition patterns were obtained which are consistent with an ordered bi-bi mechanism in which NADP(H) is the first substrate to bind and the last product released. The cinnamyl-alcohol dehydrogenase belongs to the A-specific dehydrogenases and removes the pro-R hydrogen from coniferyl alcohol. The enzyme shows many similarities with alcohol dehydrogenases from horse and rat liver and from yeast.

Alcohol Oxidoreductases↗
PubMed1992

Degradation of azo dyes by the lignin-degrading fungus Phanerochaete chrysosporium.

Under nitrogen-limiting, secondary metabolic conditions, the white rot basidiomycete Phanerochaete chrysosporium extensively mineralized the specifically 14C-ring-labeled azo dyes 4-phenylazophenol, 4-phenylazo-2-methoxyphenol, Disperse Yellow 3 [2-(4'-acetamidophenylazo)-4-methylphenol], 4-phenylazoaniline, N,N-dimethyl-4-phenylazoaniline, Disperse Orange 3 [4-(4'-nitrophenylazo)-aniline], and Solvent Yellow 14 (1-phenylazo-2-naphthol). Twelve days after addition to cultures, the dyes had been mineralized 23.1 to 48.1%. Aromatic rings with substituents such as hydroxyl, amino, acetamido, or nitro functions were mineralized to a greater extent than unsubstituted rings. Most of the dyes were degraded extensively only under nitrogen-limiting, ligninolytic conditions. However, 4-phenylazo-[U-14C]phenol and 4-phenylazo-[U-14C]2-methoxyphenol were mineralized to a lesser extent under nitrogen-sufficient, nonligninolytic conditions as well. These results suggest that P. chrysosporium has potential applications for the cleanup of textile mill effluents and for the bioremediation of dye-contaminated soil.

Azo Compounds↗