Degradation of Bromoxynil Octanoate by Strain Acinetobacter sp. XB2 Isolated from Contaminated Soil

Bromoxynil octanoate (BOO), the most widespread herbicide applied to maize, is potentially toxic to both animals and humans. In this article, a highly effective BOO-degrading bacterial strain, XB2, was isolated from the soil of a herbicide factory. The strain was identified as an Acinetobacter sp. based on its 16S rRNA gene sequence analysis, morphological, physiological, and biochemical properties. This strain could use BOO as its sole carbon source and could degrade 100?mg?l(-1) BOO to non-detectable levels in 72?h (h). The optimal pH and temperature for strain XB2's growth and degradation of BOO in MSM are 7.0 and 30°C, respectively. We propose the following pathway of BOO degradation by strain XB2: the first step is the scission of the ester bond to form bromoxynil, bromoxynil then transformed to 3,5-dibromo-4-hydroxybenzoic acid?due to the hydrolysis of nitriles, and debromination finally results in the formation of 3-bromo-4-hydroxybenzoic acid. Inoculating BOO-treated soil samples with strain XB2 resulted in a higher rate of BOO degradation than in non-inoculated soil, regardless of whether the soil had previously been sterilized.     

Acinetobacter refrigeratorensis sp. nov., Isolated from a Domestic Refrigerator

A Gram-negative bacterial strain, designated WB1^T, was isolated from a domestic refrigerator in Guangzhou, PR China. Cells of strain WB1^T were oxidase-negative, catalase-positive, strictly aerobic, non-spore-forming and non-motile coccobacilli with peritrichous fimbriae-like structures. The strain was able to grow at 10–40 °C with optimum growth at 28–30 °C, pH 6.0–8.0 (optimum, pH 7.0) and 0–6 % NaCl (w/v, optimum, 0.5 %). Phylogenetic analyses based on 16S rRNA gene and rpoB gene sequences revealed that strain WB1^T belonged to the genus Acinetobacter and was most closely related to A. indicus DSM 25388^T (97.2 % 16S rRNA gene sequence similarity) and A. radioresistens NBRC 102413^T (96.8 %). The DNA G + C content of strain WB1^T was 46.74 ± 0.04 mol % and the major fatty acids comprised summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), C_18:1 ω9c, C_16:0 and C_12:0. The predominant respiratory quinone was identified as Q-9 and the polar lipids as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and an unidentified phospholipid. Phenotypic, phylogenetic and chemotaxonomic data, including low DNA–DNA relatedness with closely related type strains, supported that strain WB1^T represents a distinct novel species in the genus Acinetobacter, for which the name Acinetobacter refrigeratorensis sp. nov. was proposed. The type strain is WB1^T (=GIMCC 1.663^T = CCTCC AB 2014197^T = KCTC 42011^T).     

Nitratireductor shengliensis sp. nov., Isolated from an Oil-Polluted Saline Soil

Two Gram-negative, non-motile, short-rod-shaped bacterial isolates, designated 110399^T and 110248, were isolated from an oil-polluted saline soil in Shengli Oilfield, Eastern China. The two strains shared 99.9 % 16S rRNA gene sequence similarity with the DNA–DNA relatedness value being 80.0 %. They were both capable to grow at 20–40 °C, pH 7–9, and 1–9 % (w/v) NaCl with the optimum growth happened at 30 °C, pH 8, and 2–6 % (w/v) NaCl. The phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains were members of Nitratireductor and most closely related to Nitratireductor pacificus pht-3B^T and N. basaltis J3^T with the 16S rRNA gene sequence similarities being 97.1 and 97.0 %. The DNA–DNA relatedness between the novel strains and two type strains were below 27 ± 7 %. The strains 110399^T and 110248 also differed from N. pacificus and N. basaltis in nitrate reduction, salt tolerance, enzyme activities, and utilization of carbon sources. The major cellular fatty acids of strain 110399^T were C_19:0ω8c cyclo (10.5 %) and Summed Feature 8 (C_18:1ω7c and/or C_18:1ω6c, 41.5 %) which are typical in the genus Nitratireductor. The predominant ubiquinone was Q-10. The genome DNA G+C content of strain 110399^T and 110248 was 61.1 and 61.7 mol%. On the basis of genetic, phenotypic, and chemotaxonomic analyses, strains 110399^T and 110248 represent a novel species within the genus Nitratireductor, for which the name Nitratireductor shengliensis sp. nov. is proposed. The type strain is 110399^T (=CGMCC 1.12519^T = LMG 27405^T).     

Hydrolytic dehalogenation of 4-chlorobenzoic acid by an Acinetobacter sp

Acinetobacter sp. strain ST-1, isolated from garden soil, can mineralize 4-chlorobenzoic acid (4-CBA). The bacterium degrades 4-CBA, starting with dehalogenation to yield 4-hydroxybenzoic acid (4-HBA) under both aerobic and anaerobic conditions, suggesting that the dehalogenating enzyme in the strain is not an oxygenase; the enzyme may catalyze halide hydrolysis. To identify the oxygen source of the C(4)-hydroxy groups in the dehalogenation step, we used H(2)(18)O as the solvent under anaerobic conditions. When resting cells were incubated in the presence of 4-CBA and H(2)(18)O under a nitrogen gas stream, the hydroxy group on the aromatic nucleus of the 4-HBA produced was derived from water, not from molecular oxygen. This dehalogenation was hydrolytic, because analysis of the mass spectrum of the trimethylsilyl derivative of one of the metabolites, (18)O-labeled 4-HBA, showed that 80% of the C4-hydroxy groups were labeled with (18)O. Hydrolytic dehalogenation of 4-CBA in intact cells has not been reported earlier. To identify substrate specificity, we next examined the ability of the strain to dehalogenate 4-CBA analogues and dichlorobenzoic acids. The results of metabolite analysis by high-pressure liquid chromatography showed that the strain dehalogenated 4-bromobenzoic acid and 4-iodobenzoic acid, yielding 4-HBA, suggesting that these compounds could be further degraded and mineralized by the strain via the beta-ketoadipate pathway, as occurs with 4-CBA. This strain, however, did not dehalogenate 4-fluorobenzoic acid, 2- and 3-chlorobenzoic acids, or 2,4-, 3,4-, and 3,5-dichlorobenzoic acids during 4 days of incubation, implying that the dehalogenating enzyme of the strain has high substrate specificity.     

4-Hydroxybenzoate Uptake in Klebsiella planticola Strain DSZ1 Is Driven by ΔpH

Klebsiella planticola strain DSZ1 has the ability to degrade different aromatic compounds such as benzoate and organochlorinated as propachlor and alachlor. DSZ1 strain cells mineralised 4-hydroxybenzoate (4HBA) through a meta-cleavage pathway, yielding protocatechuate as dihydroxylated intermediate, with a specific rate of CO₂ formation 0.12 × 10⁻⁶ (cpm/OD) h⁻¹, and a rate of 4-HBA utilisation of 0.75 mmol h⁻¹. Aerobically the 4HBA transport system is driven by gradient of protons (ΔpH), but is not ATP-driven. Under anaerobic conditions, the system can use the nitrate reduction as a final electron acceptor in respiration. A kinetic analysis of the 4HBA transport system revealed a K_t value of 16 μM with a V_max value of 25 nmol/min.mg at pH 7. Received: 28 March 2001/Accepted: 14 May 2001     

Regulation of the 4-hydroxyphenylacetic acid meta-cleavage pathway in an Acinetobacter sp

Lactate-grown cultures of $\text{Acinetobacter}$ sp. strain 3B-1 synthesize constitutively all enzymes except the 4-hydroxyphenylacetic acid-3-hydroxylase. All enzymes are further synthesized when strain 3B-1 is grown with 4-hydroxyphenylacetic acid. Induction studies with two mutant strains, one defective in the 3-hydroxylase, and the other defective in the dehydrogenase, indicate that 4-hydroxyphenylacetic acid induces the 3-hydroxylase only, and the second metabolite 3,4-dihydroxyphenylacetic acid appears to induce 3,4-dihydroxyphenylacetic acid-2,3-dioxygenase and subsequent enzymes. Thus, the enzymes of the 4-hydroxyphenylacetic acid $\text{meta}$-cleavage pathway are synthesized following at least two sequential inductive events.     

Pedobacter hainanensis sp. nov., Isolated from Seaside Soil

A Gram-negative, aerobic, rod-shaped, motile, non-spore-forming bacterial strain, designated 13-Q^T, was isolated from seaside soil under the stacks of the red algae in Hainan province in China. Identification was carried out on the basis of polyphasic taxonomy. Phylogenetic analysis of 16S rRNA gene sequences showed that strain 13-Q^T belonged to the genus Pedobacter, and the highest similarity was 94.4 % with Pedobacter terricola KCTC 12876^T. Strain 13-Q^T was able to grow at 10–40 °C, in pH 5.0–10.0, in the presence of 0–2.0 % NaCl. The major fatty acids were iso-C_15:0 (40.4 %), summed feature 3 (comprising iso-C_15:0 2-OH and/or C_16:1 ω7c) (18.9 %) and iso-C_17:0 3-OH (18.4 %). The predominant menaquinone was MK-7. The G+C content of the genomic DNA was 42.7 mol%. Strain 13-Q^T could be distinguished from the nearest phylogenetic neighbors by various chemotaxonomic and phenotypic properties. The results of the polyphasic analyses suggested that strain 13-Q^T should be considered to represent a novel species of the genus Pedobacter, for which the name Pedobacter hainanensis sp. nov. is proposed. The type strain is 13-Q^T (=CCTCC AB 2012076^T = NRRL B-59850^T).     

Adelphamoeba galeacystis n. g., n. sp., an Amoeboflagellate Isolated from Soil*

SYNOPSIS. An amoeboflagellate isolated from common soil is described. The amoeboid stage is typically limax and contains a well differentiated uroid region. The flagellate has 2 flagella, which emerge anteriorly and are equal in length. It has a ventral cytostome near the anterior border. The cyst is helmet-shaped and without opercula. Polar masses are present during nuclear division.     

Pontibacter humi sp. nov., Isolated from Mountain Soil

A Gram-negative, aerobic, non-motile, rod-shaped bacterial strain, designated as SWU8^T, was isolated from a mountain soil collected in Seoul Women’s University campus at South Korea. Phylogenic analysis, using 16S rRNA gene sequence of the new isolate, showed that strain SWU8^T belongs to the genus Pontibacter. The highest sequence similarities were 96.2 % with Pontibacter saemangeumensis GCM0142^T, 95.5 % with Pontibacter toksunensis ZLD-7^T, 95.3 % with Pontibacter roseus DSM 17521^T, and 95.1 % with Pontibacter odishensis JC130^T. Chemotaxonomic data showed that the most abundant fatty acids were summed feature 4 (comprising iso-C_17:1 I/anteiso-C_17:1 B; 26.9 %), iso-C_15:0 (25.6 %), and iso-C_17:0 3OH (10.6 %), and major polar lipid was phosphatidylethanolamine. The DNA G+C content of strain SWU8^T was 48.5 mol%. Together, the phenotypic, phylogenetic, and chemotaxonomic data supported that strain SWU8^T presents a novel species of the genus Pontibacter, for which the name Pontibacter humi sp. nov. is proposed. The type strain is SWU8^T (=KEMC 9004-131^T = JCM 19178^T).     

Cohnella humi sp. nov., Isolated from Russian Soil

A Gram-positive, catalase and oxidase positive, rod-shaped bacteria, and spore-forming, designated as J20-3^T was isolated from a peat soil, collected near a coal mine at Prokopyevsk, (GPS; N53°52′51″, E86°43′39″) Kemerovo Oblast, Russia. A polyphasic taxonomy study using phenotypic, phylogenetic, and genotypic method was performed to characterize strain J20-3^T. Comparative 16S rRNA gene sequence analysis indicated that strain J20-3^T represented a novel subline within the genus Cohnella in the family Paenibacillaceae. According to 16S rRNA gene sequence, strain J20-3^T showed 93.7–97.2 % similarity levels with other Cohnella species. Strain J20-3^T exhibited relatively low level of DNA–DNA hybridization value with type strains KACC 11643^T (40 %), KACC 11771^T (37.5 %), and KACC 15372^T (30.5 %). The strain showed typical chemotaxonomic characteristic of the genus Cohnella, with the presence of predominant respiratory quinone MK-7; major fatty acids are C_15:0, C_16:0, iso, and C_16:0. The DNA G+C content of the strain J20-3^T was 56.3 mol%. The polar lipid profile of the strain J20-3^T included major amount of diphosphatidylglycerol, phosphatidylglycerol, and phosphoatidylethanolamine. On the basis of its phenotypic and genotypic properties, and its phylogenetic distinctiveness, strain J20-3^T should be classified as a novel species in the genus Cohnella, for which the name Cohnella humi sp. nov. is proposed.     

Oceanobacillus halophilum sp. nov. Isolated from a Mangrove Forest Soil

A halophilic, aerobic bacterium, designated GD01^T, was isolated from a mangrove forest soil near the South China Sea. Cells of strain GD01^T were Gram staining positive, oxidase positive, and catalase positive. The strain was rod shaped and motile by means of peritrichous flagella and produced ellipsoidal endospores. The strain was able to grow with NaCl at concentrations of 0.5–12 % (optimum 3–5 %, w/v), at temperatures of 20–50 °C (optimum 30 °C), and at pH 6.0–8.5 (optimum pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain GD01^T formed a cluster with O. profundus DSM 18246^T (96.4 % 16S rRNA gene sequence similarity), O. caeni KCTC 13061^T (95.4 %), and O. oncorhynchi JCM 12661^T (94.5 %). The G+C content of strain GD01^T was 38.7 mol%. The major respiratory quinone was MK-7. The major cellular fatty acids (>5 %) were anteiso-C_15:0, iso-C_16:0 (13.7 %), anteiso-C_17:0 (12.6 %), iso-C_15:0 (9.9 %), iso-C_14:0 (9.5 %), and C_16:0 (5.0 %). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, glycolipid, four unknown lipids, and four unknown phospholipids. Based on phenotypic characteristics, chemotaxonomic features, and phylogenetic analysis based on 16S rRNA gene sequences, the strain was identified to represent a distinct novel species in the genus Oceanobacillus, and the name proposed is Oceanobacillus halophilum sp. nov. with type train GD01^T (=CCTCC AB 2012863^T = KCTC 33101^T).     

Rhizobium halotolerans sp. nov., Isolated from Chloroethylenes Contaminated Soil

The strain designated as AB21^T was isolated from chloroethylenes contaminated soil. Cells are gram-negative, aerobic, non-spore-forming, and motile rods. Phylogenetic analysis based on 16S rRNA gene sequence showed that it belonged to the genus Rhizobium, and was closely related to Rhizobium sullae IS 123^T (97.4 %), Rhizobium yanglingense SH 22623^T (97.2 %), Rhizobium gallicum R 602sp^T (97.1 %), Rhizobium alamii GBV 016^T (97.0 %), and Rhizobium monogolense USDA 1844^T (97.0 %). It showed less than 97 % identity with the remaining Rhizobium species. This novel isolate grew optimally at 25–37 °C (optimum, 30 °C) and pH 6–9 (optimum, pH 8.0). It grew in the presence of 0–4 % (w/v) NaCl, tolerating a 4 % (w/v) NaCl. DNA–DNA hybridization experiment shows less than 53 % binding with closely related Rhizobium. Predominant quinone is ubiquinone (Q-10). The major fatty acids were summed feature 8 (composed of C_18:1 ω7c/C_18:1 ω6c), C_19:0 cyclo ω8c, and C_16:0. The G+C molar content is 62.5 mol%. Based on the polyphasic analysis, strain AB21^T is referred to be a novel species of the genus Rhizobium for which the name Rhizobium halotolerans sp. nov. is proposed. The type strain is AB21^T (=KEMC 224-056^T = JCM 17536^T).     

Characterization of Sphingomonas sp. Ant 17, an Aromatic Hydrocarbon-Degrading Bacterium Isolated from Antarctic Soil

Sphingomonas sp. strain Ant 17 was isolated from fuel-contaminated soil collected at Scott Base, Ross Island, Antarctica. We anticipated that Ant 17 would be a good model organism for studying cold climate bioremediation, and therefore determined its biodegradation capabilities and tolerance of potentially growth-limiting environmental conditions. Sphingomonas sp. Ant 17 degrades the aromatic fraction of several different crude oils, jet fuel, and diesel fuel at low temperatures and without nutrient amendment. It utilizes or transforms a broad range of pure aromatic substrates, including hydrocarbons, heterocycles, and aromatic acids and alcohols. Ant 17 grows at temperatures of 1 degree C to 35 degrees C and mineralizes radiolabeled phenanthrene over a range of more than 24 degrees C. This psychrotolerant isolate appears to utilize hydrocarbons more efficiently at low temperatures than would be predicted by mesophilic enzyme kinetics. The optimum pH for growth was 6.4 at 22 degrees C, with extended lag phases observed in more alkaline media. However, there was less effect of pH on lag phase at lower temperatures. Ant 17 displayed greater tolerance to UV irradiation and freeze-thaw cycles than the hydrocarbon-degrading isolate Sphingomonas sp. WPO-1, which may reflect adaptation to its Antarctic soil environment. However, it was more sensitive than expected to desiccation and to low concentrations of NaCl and CaCl(2). Ant 17 was phenotypically stable and lacked detectable plasmids, suggesting a chromosomal location for genes encoding aromatic degradation enzymes. Its broad aromatic substrate range and tolerance of low and fluctuating temperature and low nutrients make Sphingomonas sp. Ant 17 a valuable microbe for examining fuel spill bioremediation in cold soils.     

Enzymic Dehalogenation of 4-Chlorobenzoyl Coenzyme A in Acinetobacter sp. Strain 4-CB1

[This corrects the article on p. 1386 in vol. 58.].