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1.
Biocontrol Sci ; 22(4): 187-203, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29279576

RESUMO

 Natural biodegradation of heavy oil in the marine environment can be accelerated by the addition of nutrients or seeding of pre-selected microorganisms. In this study, a microcosm experiment was conducted to investigate the effects of inorganic nutrient supplementation (biostimulation) and bacterial consortium amendment (bioaugmentation) on the natural degradative processes of artificially contaminated sediment. Our results revealed that the addition of nutrients had greater effect on remediation than the addition of bacterial cells. Supplementation of inorganic nutrients promoted and sustained the growth of oil-degrading and heterotrophic bacteria throughout the experimental period. Highest reduction in the total petroleum hydrocarbons, and of their components, n-alkanes, polycylic aromatic hydrocarbons (PAHs) and alkyl PAHs, were obtained in the biostimulated microcosms. Changes in the bacterial community were monitored by the PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) method targeting the 16S rDNA gene. Results revealed different responses of the bacterial community to the addition of heavy oil and remediation agents. Shifts in the bacterial communities in the seawater were more dynamic than in the sediment. Results of this study showed that addition of remediation agents significantly enhanced the natural biodegradation of heavy oil in a sediment-seawater microcosm trial.


Assuntos
Bactérias/metabolismo , Biodegradação Ambiental , Sedimentos Geológicos/microbiologia , Hidrocarbonetos/metabolismo , Poluição por Petróleo , Bactérias/classificação , Bactérias/genética , Cromatografia Gasosa-Espectrometria de Massas , Microssomos , RNA Ribossômico 16S/genética , Água do Mar/microbiologia , Microbiologia da Água , Poluentes Químicos da Água
2.
Biocontrol Sci ; 21(3): 173-7, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27667522

RESUMO

Antifungal bacteria (AB) in root rot fungus (RRF)-contaminated sweet potato farms were isolated, and seven strains were initially chosen as antagonistic candidates. An antagonistic test by using the mycelial disk placement method revealed that one AB strain by itself could inhibit the RRF growth. This AB strain was identified as Bacillus polyfermenticus based on phylogeny of 16S ribosomal RNA genes. Two AB strains (Bacillus aerophilus) displayed high levels of antifungal activity when paired with photosynthetic bacterial strain A (a purple nonsulfur photosynthetic bacterium Rhodopseudomonas faecalis). The results suggest the possible use of the isolates as agents for the biological control of the RRF infection of agricultural products in fields of cultivation.


Assuntos
Antibiose , Bactérias , Fenômenos Fisiológicos Bacterianos , Fungos/fisiologia , Fotossíntese , Raízes de Plantas/microbiologia , Bactérias/classificação , Bactérias/genética , Filogenia , RNA Ribossômico 16S/genética
3.
Biocontrol Sci ; 19(1): 11-22, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24670614

RESUMO

We examined the effectiveness of cocopeat and rice hull powder obtained from agricultural wastes as biocarriers for an oil-degrading bacterial consortium. Scanning electron microscopy revealed colonization and strong attachment of bacterial cells on the surface of both carriers. Results of a 60-day in vitro seawater bioremediation trial showed significant oil reduction and high cultivable bacterial counts in treatments augmented with the carrier-attached bacterial consortia compared to treatments supplemented with the same consortium in free living and encapsulated forms. Significant degradations in both aliphatic and aromatic fractions were obtained in treatments augmented with carrier-immobilized consortia. The developed immobilized cells showed sustained activities and viabilities during storage for six months. Results of this study demonstrated that inexpensive waste materials can be utilized as biocarriers of an oil-degrading consortium and that immobilization on biocarriers can enhance the bioremediation of oil-contaminated seawater.


Assuntos
Bactérias/metabolismo , Recuperação e Remediação Ambiental/métodos , Oryza/microbiologia , Água do Mar/microbiologia , Poluentes Químicos da Água/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biodegradação Ambiental , Hidrocarbonetos/metabolismo , Petróleo/análise , Poluição por Petróleo , Água do Mar/química , Resíduos/análise
4.
Biocontrol Sci ; 18(1): 29-40, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23538849

RESUMO

The physicochemical properties and bacterial community in sediments of Lake Shiraishi, a lake with brackish water, were characterized to elucidate the influence of oyster farming and seawater and freshwater inflow. Physicochemical analyses suggested the marine origin of the sediment at the mouth of the lake, while higher organic matter load and the resultant anaerobic, reductive condition of the sediments of the inner part were observed. The bacterial community in the sediments reflects these sediment environments: the bacterial community in the vicinities of oyster farms included sulfate-reducing bacteria (SRB) , although sulfur-oxidizing bacteria (SOB) were found at all the sampling sites. In addition, similarity of the band profiles obtained with 16S ribosomal RNA gene (16S rDNA) -denaturing gradient gel electrophoresis (DGGE) decreased in proportion to the distance from the mouth of the lake to the oyster farms in the inner part. This study was able to characterize the microbial community shift in brackish lake sediments with an oyster aquaculture system through the molecular fingerprinting technique, DGGE, in relation to their physicochemical characteristics.


Assuntos
Aquicultura , Bactérias/classificação , Sedimentos Geológicos/microbiologia , Lagos/microbiologia , Ostreidae , Animais , Bactérias/genética , Biodiversidade , Carbono/química , Ecossistema , Sedimentos Geológicos/química , Geologia , Japão , Lagos/química , Nitrogênio/química , Ostreidae/crescimento & desenvolvimento , Filogenia , RNA Ribossômico 16S/genética , Sulfetos/química , Enxofre/química
5.
Biocontrol Sci ; 18(1): 41-51, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23538850

RESUMO

The effect of an oxygen-releasing compound (ORC) magnesium peroxide (MgO(2)) on the changes in the bacterial community in organically polluted sediment of aquaculture farms was tested in a microcosm experiment. The sediment, to which fish feed was added, was treated with 1% or 5% MgO(2). The addition of fish feed induced a highly reduced environment with low redox potential, high total sulfides, and abundance of sulfate-reducing bacteria (SRB) . Although the sediment remained highly reduced at 1% MgO(2), there was a significant reduction of total sulfides, increase of redox potential, and resultant reduction of SRB. The bacterial community clearly changed with the treatments according to denaturing gradient gel electrophoresis (DGGE) analysis of 16S ribosomal RNA gene (16S rDNA) . Aerobes disappeared in the fish feed-added sediment, and some SRB emerged in place of these aerobes. On the other hand, the SRB disappeared in the ORC-amended sediment due to its highly oxic condition. This study revealed the bacterial community in the sediments was affected mainly by the redox potential and resultant sulfides produced by SRB, but total organic carbon and nitrogen were not determinants of the microbial population.


Assuntos
Aquicultura , Bactérias/classificação , Peixes , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Compostos de Magnésio/química , Peróxidos/química , Animais , Bactérias/genética , Biodiversidade , Ecossistema , Meio Ambiente , Filogenia , RNA Ribossômico 16S/genética , Sulfetos/química
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