Phenol metabolism by two microorganisms isolated from Amazonian forest soil samples

Two microorganisms isolated from Amazonian forest soil samples and identified as Candida tropicalis and Alcaligenes faecalis were capable of degrading phenol (16 and 12 mM, respectively) at high salt concentrations (15% and 5.6%, respectively). Chromatographic and enzymatic studies revealed that each microorganism cleaved phenol at the ortho position with total phenol mineralization. ¹⁴C-phenol mineralization assays showed that both microorganisms assimilated about 30% of the total label. No phenol degradation metabolite (i.e., catechol, cis, cis-muconic acid) was detected in the intercellular medium. The presence of phenol hydroxylase (EC 1.14.13.7) and catechol 1,2-dioxygenase (EC 1.13.11.1) extracellular activity suggested that these microorganisms may secrete these enzymes into the extracellular medium. Journal of Industrial Microbiology & Biotechnology (2000) 24, 403–409. Received 02 November 1999/ Accepted in revised form 08 March 2000     

Factors determining rock phosphate solubilization by microorganisms isolated from soil

Forty two soil isolates (31 bacteria and 11 fungi) were studied for their ability to solubilize rock phosphate and calcium phosphate in culture medium. Eight bacteria and 8 fungi possessed solubilizing ability. Pseudomonas cepacia and Penicillium purpurogenum showed the highest activity. There was a correlation between final pH value and titratable acidity (r=–0.29 to –0.87) and between titratable acidity and soluble phosphate (r=0.22 to 0.99). Correlation values were functions of insoluble phosphate and of the group of microorganisms considered. A high correlation was observed between final pH and soluble phosphate only for the rock phosphates inoculated with the highest concentration of solubilizing bacteria (r=–0.73 to –0.98).     

Antibiotic activity of fungi isolated from soil samples from Indonesia

Two hundred and thirteen fungal cultures were recovered from 88 soil samples from different parts of Indonesia; 39.4% belonged to the genusPenicillium, 19.7% to the genusAspergillus, 9.9% to the genusFusarium and the rest to different systematic groups. One hundred and fifty two cultures were antibiotically active; 80% of these were antagonists ofBacillus subtilis, 55% ofEscherichia coli, 20% ofSaccharomyces cerevisiae and 37% ofCandida pseudotropicalis. In agreement with previous observations it was found that the activity spectrum of antagonists was related to the altitude above sea level at which they were found. As the altitude increased, the incidence of antagonists with both antibacterial and antifungal activity decreased, but the incidence of antagonists with only antibacterial or only antifungal activity increased. Fungi of the generaPenicillium andAspergillus were the most frequent antibiotic producers. The incidence of penicillin producers was much lower than in collections of fungi isolated in higher latitudes (China, Bulgaria, Slovakia).     

Intergeneric coaggregation of strains isolated from phenol-degrading aerobic granules

This work aims at exploring the intergeneric coaggregation of the pairs of strains, Acinetobacter calcoaceticus I6 and Bacillus thuringiensis I2 or Candida tropicalis I9 (with GenBank accession numbers EU250016, EU036759, and DQ515822) isolated from phenol-degrading aerobic granules. The I2 and I6 are functionally similar stains, while the I6 and I9 are functionally dissimilar strains. The lectin-saccharide interaction controlled the coaggregation of both the I2+I6 and I6+I9 pairs, with the protein adhesin being associated with the strain I6, and the complementary galactosamine-like or fucose-like sugar receptor with the strain I2 or I9, respectively. The rod-like I2 cells bridged the clusters of I2 or I6 cells to form aggregates, while the small I6 cells attached on and modified the surface of I9 to form aggregates.     

2,4-Dichlorophenoxyacetic acid degradation in methanogenic mixed cultures obtained from Brazilian Amazonian soil samples

Biodegradation - 2,4-Dichlorophenoxyacetic acid (2,4-D) is the third most applied pesticide in Brazil to control broadleaf weeds in crop cultivation and pastures. Due to 2,4-D’s high mobility...     

Immunomodulators isolated from microorganisms

Microbial products are surveyed that have an immunoregulatory activity, both from the realm of low-molar-mass compounds and from the group of naturally occurring polymers. The data include in most cases the producer organism or source, a brief chemical characteristic and biological activity. Various groups of substances are compared, the drawbacks attendant on their acquisition and application are pointed out and their advantageous properties are specified. Translated by K. Sigler     

生物冶金中耐盐浸矿微生物的研究进展

耐盐浸矿微生物是指在发挥矿物浸出功能时对所处的含盐环境具有一定耐受能力的一类浸矿微生物。耐盐浸矿微生物因其可以适应不同浓度的氯化钠等盐,因而在淡水资源缺乏地区的生物冶金中具有广泛的应用价值。本文从耐盐浸矿微生物的种类、耐盐机制及其在矿物生物浸出中的应用现状进行了系统性综述,为耐盐浸矿微生物的研究和应用提供参考。     

Physiological traits of bacterial strains isolated from phenol-degrading aerobic granules

The physiological characteristics of ten bacterial strains isolated from phenol-degrading aerobic granules were evaluated in order to identify competitive traits for dominant growth in aerobic granules. The ten strains showed a wide diversity in specific growth rates and oxygen utilization kinetics, and could be divided into four catabolic types of phenol degradation. While some strains degraded phenol mainly via the meta pathway or the ortho pathway, other strains degraded phenol via both these pathways. The ten strains also exhibited high levels of autoaggregation and coaggregation activity. Within the collection of ten strains, 36.7% of all possible strain pairings displayed a measurable degree of coaggregation. Strain PG-08 possessed the strongest autoaggregation activity and showed significant coaggregation (coaggregation indices of 67% to 74%) with PG-02. The three strains PG-01, PG-02 and PG-08 belonging to dominant groups in the granules possessed different competitive characteristics. Microcosm experiments showed the three strains could not coexist at the high phenol concentration of 250 mg L(-1), but could coexist at lower phenol concentrations in a spatially heterogeneous environment. This study illustrated that the spatial heterogeneity provided by the aerobic granules led to niche differentiation and increased physiological diversity in the resident microbial community.     

Molecular characterization of phenol-degrading bacteria isolated from different Egyptian ecosystems

Twelve selected phenol-degrading bacterial isolates were obtained on phenol agar plates using culture enrichment technique. Molecular identification of the isolates was performed using eubacterial 16S rRNA PCR specific primers. Based on 16S rDNA sequence analysis, the results revealed that the majority of the isolates (8 out of 12) are affiliated to the g-subdivision of Proteobacteria. Four out of the eight isolates are closely related to the genus Acinetobacter. Molecular heterogeneity among the phenol-degrading isolates was further investigated by using rep-PCR chromosomal fingerprinting and correlated with plasmid and antibiotic profile analysis. Rep-PCR results strongly confirmed that the bacterial isolates from different environmental sites produced different fingerprinting patterns. The mineralization of phenol by all isolates was evaluated using 14C-labeled phenol assay. Phenol mineralization ranged from 55% (W-17) to 0.4% (Sea-9). This was further confirmed by the detection of several monoaromatic and polyaromatic degrading genes, e.g., pheA, MopR, XylE, and NahA. In addition, catalytic enzymes such as catalase and dioxygenase were also monitored.     

Degradation of vanillic acid and production of guaiacol by microorganisms isolated from cork samples

The presence of guaiacol in cork stoppers is responsible for some cases of cork taint causing unpleasant alterations to wine. We have performed a characterization of the cork-associated microbiota by isolating 55 different microorganisms: eight yeast, 14 filamentous fungi or molds, 13 actinomycetes and 20 non-filamentous bacteria. A screening for degradation of vanillic acid and guaiacol production showed that none of the filamentous fungi could achieve any of these processes. By contrast, five of the eight yeast strains isolated were able to degrade vanillic acid, although it was not converted to guaiacol. Guaiacol production was only detected in four bacterial strains: one isolate of Bacillus subtilis and three actinomycetes, Streptomyces sp. A3, Streptomyces sp. A5 and Streptomyces sp. A13, were able to accumulate this compound in both liquid media and cultures over cork. These results suggest that guaiacol-mediated cork taint should be attributed to the degradative action of vanillic acid by bacterial strains growing on cork.     

PCR-based identification of Bacillus thuringiensis isolated from soil samples in Nigeria

Six isolates of Bacillus thuringiensis isolated from soil samples confirmed to be toxic to mosquito larvae were differentiated using a PCR-Based technique. Three of these isolates initially identified using a serological technique were further differentiated with the PCR amplification of the delta-endotoxin target sequences. Using the total DNA of isolates as template, at least four isolates yielded amplicons one or all the crystal protein genes, cryI a, b, c, or II with sizes ranging from 238-1070 bp. None of these isolates yielded an amplicon for any of Cry IV A, B and D tested. Of the four isolates identified by PCR technique one isolate remained unidentified by serology.     

Horizontal arsC gene transfer among microorganisms isolated from arsenic polluted soil

The study of recent evolution of the arsC genes amplified from microorganisms inhabiting a Colombian oil-polluted soil with high concentrations of arsenic was performed through the isolation of 26 bacterial morphotypes resistant to 10 mM of arsenate. A 353 bp fragment of the gene coding for arsenate-reductase enzyme (i.e. arsC), and a 500 bp 16S rDNA partial sequence were sequenced for 16 morphotypes of the 26 previously isolated. arsC sequences clustered on the same clade with previously reported arsC chromosomal genes of Escherichia coli and Shigella sp.; while 16S rDNA sequences grouped within the genus Pseudomonas and Bacillus. The GC content and the Codon Adaptation Index (CAI) were calculated and statistically compared, both supported the previous results. The Isolation-Migration model (IM model) was applied to calculate the genetic flux between each clade defined by the phylogenetic analysis. In general, the existence of recent horizontal gene transfer (HGT) events was confirmed, and the presence of the arsC gene in Bacillus sphaericus is reported for the first time.     

Isolation and selection of phenol-degrading microorganisms from industrial wastewaters and kinetics of the biodegradation

Among 22 species of microorganisms isolated from phenol-containing wastewaters, Candida parapsilopsis was found to be capable of growth on a medium with 1 g/L phenol. Kinetic parameters of phenol biodegradation in a batch reactor were determined by measuring biomass growth rates and phenol concentration as a function of fermentation time. The Haldane equation described cell growth adequately, with kinetic constants mumax = 0.174/h, KS = 11.2 mg/L and Ki = 298 mg/L.     

Quantitative field testing Rotylenchulus reniformis DNA from metagenomic samples isolated directly from soil

A quantitative PCR procedure targeting the β-tubulin gene determined the number of Rotylenchulus reniformis Linford & Oliveira 1940 in metagenomic DNA samples isolated from soil. Of note, this outcome was in the presence of other soil-dwelling plant parasitic nematodes including its sister genus Helicotylenchus Steiner, 1945. The methodology provides a framework for molecular diagnostics of nematodes from metagenomic DNA isolated directly from soil.     

Perchlorate-reducing microorganisms isolated from contaminated sites

An extensive microcosm survey of perchlorate-contaminated sites was undertaken to assess the ability of indigenous microorganisms to degrade perchlorate. Samples from 12 contaminated sites and from one pristine location were analysed. Perchlorate was degraded to below detection limit in all electron donor-amended microcosms. Perchlorate-reducing microorganisms (PRMs) were numerous at most of these sites. Sixteen distinct PRMs were isolated that were phylogenetically related to either Dechloromonas in the Beta Proteobacteria (9/16 isolates) or to Azospirillum in the Alpha Proteobacteria (7/16 isolates). The majority of previously isolated PRMs are in the Beta Proteobacteria related to Dechloromonas or Dechlorosoma. This study indicates that PRMs of the genus Azospirillum may be more prevalent at contaminated sites than the current record of isolates suggests. Cell yields, electron donor to perchlorate ratios and maximum specific growth rates were similar among the isolates and similar to the few previously published values. However, the Monod half-saturation constants for perchlorate for the two Azospirillum isolates characterized were lower than those measured for other genera, suggesting that they may be more effective at low concentrations of perchlorate. These results extend the current understanding of PRMs from diverse environments and provide added confidence that microbial perchlorate reduction is ubiquitous, even at highly contaminated sites, and can be harnessed effectively for bioremediation.     

Isolation of polyacrylamide-degrading microorganisms from soil

Two polyacrylamide-degrading bacterial strains, No. 2 and No. 11, were isolated from soil, and identified asBacillus sphaericus No. 2 andAcinetobacter sp. No. 11, respectively. Both strains grew on medium containing polyacrylamide as sole carbon and nitrogen sources.B. sphaericus No. 2 andA. sp. No. 11 reduced by 16% and 19% of the initial polyacrylamide concentration, respectively. Optimal pH and temperature in growth ofAcinetobacter sp. No. 11 were 8.0 and 37°C, respectively. After 14-day cultivation ofA. sp. No. 11, the average molecular weight of polyacrylamide has been shifted from 2.3×10⁶ to 0.5×10⁶.