Biodegradation of the herbicide Diuron in soil by indigenous actinomycetes

Three actinomycete strains isolated from soil treated with 2,4-D were able to degrade the herbicide Diuron in vitro. Strain CCT 4916 was the most efficient, degrading up to 37% of applied Diuron (100 mg Kg(-1) soil) in 7 days, as measured by HPLC and UV/VIS spectroscopy. All strains showed protease and urease activity; intracellular activity of metapyrocatechase and pyrocatechase were not found. Actinomycete strain CCT 4916 produced manganese peroxidase, which could be potentially related to degradation of Diuron. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.37354154

J. C. R. Dow: The Management of the British Economy 1945-60. Cambridge University Press, London 1964, XIX+443 sider, $ 11,50.

Phylogenetic and statistical analyses of 16S rRNA gene libraries were used for the investigation of actinobacterial communities present in two tropical estuarine sediments (Santos-Sao Vicente estuary, Brazil). The libraries were constructed from samples collected at the brackish end of the estuary, highly hydrocarbon-contaminated, and at the marine end, uncontaminated. Clones from the marine end of the estuary were all related to sequences from non-cultured Actinobacteria and unidentified bacteria recovered from a wide range of environmental samples, whereas clones from the brackish end were mainly related to sequences from cultured Actinobacteria. Statistical analyses showed that the community recovered from the hydrocarbon-contaminated sediment sample, at the brackish end, was less diverse than the uncontaminated one, at the marine end, and that the communities from the two libraries were differently structured, suggesting that these may have not originated from the same community. The recognition of the spatial pattern of actinobacterial distribution in a natural environment is a first step towards understanding the way these communities are organized, providing valuable data for further investigations of their taxonomic and functional diversity.86431732

Isolation and characterization of alachlor-degrading actinomycetes from soil

Alachlor (2-cloro-N-(methoxymethyl)-N-(2,6-diethylphenyl)-acetamide) is an extremely toxic and highly mobile herbicide that is widely used for pre-emergence control of grasses and weeds in many commercial crops in Brazil. In order to select soil actinomycetes able to degrade this herbicide, fifty-three actinomycete strains were isolated from soil treated with alachlor using selective conditions and subjected to in vitro degradation assays. Sixteen isolates were shown to be tolerant to high concentrations of the herbicide (up to 720 mg L-1), and six of these were able to grow and degrade >= 50% alachlor (72 mg L-1) in mineral salts medium. Morphological and phylogenetic analysis enabled the assignment of the alachlor-degrading strains to the genus Streptomyces. Strain LS151 was related to the type strains of Streptomyces capoamus/Streptomyces galbus, whereas strains LS143 and LS153 were related to Streptomyces bikiniensis. The remaining strains, LS166, LS177 and LS182, were similar in morphological features and recovered in a single cluster based on 16S rDNA sequence analysis, but shown to be distinct on the, basis of genomic fingerprint data (rep-PCR). Though a definitive taxonomic assignment of alachlor-degrading strains was not possible, these data indicate that ability to degrade this pesticide was detected in different Streptomyces taxa.872818

Characterization of selected strains of Mucorales using fatty acid profiles

The fatty acid profiles of several fungi of the order Mucorales (Zygomycetes), including Backusella lamprospora (Lendner) Benny and R.K. Benj., Benjaminiella youngii P.M. Kirk, Circinella simplex van Tieghem, Cunninghamella blakesleeana Lendner, Mortierella ramanniana (Moller) Linnem., Mucor circinelloides f. janssenii (Lendner) Schipper, Mycotypha microspora Fenner, Rhizomucor miehei (Cooney and R. Emerson) Schipper and Rhizomucor pusillus (Lindt) Schipper, and of Volutella sp. Fr., from the class Ascomycetes, were qualitatively analysed by gas-liquid chromatography in order to determine the taxonomic value of these chemotaxonomic markers. The fatty acids present in all strains were palmitic (16:0), oleic (18:1), linoleic (18:2) and gamma-linolenic (18:3) acid, with the exception that the latter was not found in Volutella sp. Chemotaxonomic markers for some species and genera were obtained, including a non-identified fatty acid, FAME8 (minimum and maximum retention times of 27.92 and 28.28 minutes) for Rhizomucor miehei CCT 2236 and Rhizomucor pusillus CCT 4133, and FAME3 (minimum and maximum of 16.53 and 16.61 minutes) for Benjaminiella youngii CCT 4121. The chemotaxonomic marker of the order Mucorales was the fatty acid 18:3 omega 6, confirming previous data from literature. The results of the present study suggest that qualitative fatty acid analysis can be an important chemotaxonomic tool for the classification of fungi assigned to the order Mucorales (Zygomycetes).29427628

Networking the microbial diversity information

The Internet, the electronic global network of computers, has expanded significantly over the last few years, connecting segments from academia, industry and the private sector, The use of the Internet by researchers has diversified substantially from the primordial exchange of electronic messages to the current use of highly developed graphic interfaces capable of accessing images, sounds and retrieving information from databases in different computers around the world, The reduced costs for data storage and ease of connection to the net have nourished a steady exponential growth in the number of sites, Microbiologists now benefit from a wealth of databases and Web sites with microbiological information, ranging from culture collection data, information on microbial diversity, taxonomic and phylogenetic data, biotechnological applications and taxonomic expertise. Efforts are required to stimulate the integration of complex molecular and image databases with more traditional information resources, such as bibliographic, strain data, compendia of species descriptions and metabolic products databases. Coordinating and linking mechanisms are needed in order to promote the development of protocols, guidelines and minimal standards to ensure data quality, Future challenges to the scientific use of Internet resources include the setting up of clearing-house mechanisms and virtual libraries for the organization of the microbiological resources on the network.174179549850

Acyl-homoserine lactones from Erwinia psidii R. IBSBF 435(T), a guava phytopathogen (Psidium guajava L.)

The phytopathogen Erwinia psidii R. IBSBF 435(T) causes rot in branches, flowers, and fruits of guava (Psidium guajava L.), being responsible for crop losses, and has no effective control. It was demonstrated that this strain produces two compounds [S-(-)-N-hexanoyl and N-heptanoyl-homoserine lactone], both belonging to the class of quorum-sensing signaling substances. A protocol using gas chromatography-flame ionization detection with chiral stationary phase is described for the absolute configuration determination of a natural acyl-homoserine lactone. Biological assays with specific reporter and synthesis of identified substances are also described. This is the first report on the N-heptanoyl-homoserine lactone occurrence in the Erwinia genus.53166262626

STUDIES OF THE GENETIC EXPRESSION OF 31A-FIMBRIAE BY 2 BOVINE SEPTICEMIC ESCHERICHIA-COLI STRAINS

Using transposon tnphoA, classical bacterial genetic assays, SDS-PAGE and Western blot of superficial proteins, we have studied the expression of the 31A fimbriae of two bovine wild-type septicaemic Escherichia coli strains. The genes responsible for encoding colonization factor 31A were located in both the plasmid (strain BZ2468) and the chromosome (strain BZ43). The results obtained using HeLa cell cultures led us to believe that the BZ43 strain could have another colonization factor besides 31A, since one mutant, which did not express fimbriae, was still able to adhere to HeLa cells.17436537

Biodegradation of alachlor by soil streptomycetes

Streptomycetes resistant to the herbicide alachlor [2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide] were used in degradation assays to characterize the products of alachlor biodegradation. Of six strains tested, Streptomyces sp. LS166, LS177, and LS182 were able to grow at an alachlor concentration of 144 mg l(-1) and degraded approximately 60-75% of the alachlor in 14 days, as evaluated by high performance liquid chromatography. The alachlor biodegradation products were identified by gas chromatography-mass spectrometry based on mass spectral data and fragmentation patterns. All compounds detected in these assays were similar for all streptomycetes strains tested, and involved dechlorination with subsequent N-dealkylation and cyclization of the remaining N-substituent with one of the ethyl groups to produce indole and quinoline derivatives. The enzymatic pathway used by Streptomyces sp. LS182 did not generate DEA (2',6'-diethylaniline), a carcinogenic derivative of alachlor reported in other studies. Given the high degradation rates observed here, the Streptomyces strains tested may be useful in the degradation/detoxification processes of alachlor.64571271

First evaluation of the Brazilian microorganisms biocatalytic potential

The biocatalytic potential of two novel Brazilian strains of Aspergillus niger and Rhodotorula glutinis, revealed enantioselective epoxide hydrolase activity in the asymmetrization of meso-epoxide and monosubstituted epoxides respectively. These two types of oxirane derivatives are not usually good substrates for biocatalytic enantioselective conversion. (C) 1999 Elsevier Science Ltd. All rights reserved.38102237224

Diversity of a Xylella fastidiosa population isolated from Citrus sinensis affected by Citrus variegated chlorosis in Brazil

Diversity of a population of Xylella fastidiosa isolated from sweet orange plants showing citrus variegated chlorosis (CVC) symptoms was assessed by PCR-based techniques. Thirty-seven strains were isolated throughout the 1997 year in the orange belt of Sao Paulo State, Brazil. Strains isolated from coffee, grape, oleander and plum were also included as outgroup reference strains. PCR amplification of the spacer sequence between the 16-23S rDNA yielded one fragment of 1.2 kb. Digestion with restriction enzymes, DdeI, HinfI or Sau3AI generated identical RFLP patterns for citrus and coffee strains, which could be distinguished from the strains isolated from the other hosts. Eight RAPD primers were also used and the results showed similarity from 80 to 100% within the CVC population. Three prevalent haplotypes comprising 24 CVC strains showed a high level of similarity (95%). Strains from the other hosts clustered apart from CVC strains, forming distinct groups.21459359