Biodegradation of methyl tert-butyl ether by Kocuria sp.

Methyl tert-butyl ether (MTBE) has been used to replace the toxic compounds from gasoline and to reduce emission of air pollutants. Due to its intensive use, MTBE has become one of the most important environment pollutants. The aim of this paper is isolation and identification of the bacteria from wastewater sample of “HIP Petrohemija” Pančevo (Serbia), capable of MTBE biodegradation. The results of the investigation showed that only the bacterial isolate 27/1 was capable of growth on MTBE. The result of sequence analyzes of 16S rDNA showed that this bacterial isolate belongs to the Kocuria sp. After the incubation period of 86 days, the degradation rates of initial MTBE concentration of 25 and 125 μg/ml were 55 and 36%, respectively. These results indicated that bacteria Kocuria sp. is successfully adapted on MTBE and can be potentially used in bioremediation of soils and waters contaminated with MTBE

Degradacija različitih koncentracija MTBE-a pomoću Mucor hiemalis

In the last twenty years there has been increased usage of metil tertiary butil eter (MTBE) which led to it's high presence in the environment. Environmental Protection Agency (EPA) has characterized MTBE as potentially cancerogenic substance and proposed the methods for it's removal from natural sources. Bioremediation represents the world trend in developing remediation technologies, and is a complex process which assumes using different microorganisms. The etheric bond in MTBE's molecule is persistent in the environment. Still, microorganisms are capable for using this organic compaund as carbon and energy source due to their various enzyme systems and transform it into non toxic products. The objective of this research is investigation of biodegradability of various concentrations of MTBE (76, 100 438 and 746 ppm) by Mucor hiemalis 139ž. This strain has been isolated from the soil of NIS Oil Raffinery Pančevo, contaminated with organic pollutants. The degradation process was observed during 8 days of incubation in aerobic conditions. The MTBE’s degradation was detected by gas chromatography with flame ionizing detector (GC/FID). After 12 hours of incubation the concentration of MTBE was reduced. The MTBE’s reduction ranging form 47 to 76% from the initial concentration was detected after 8 days. The degradation level depended on the starting concentration of MTBE. These results indicate the possibility for using the authentic strain Mucor hiemalis in the bioremediation processes of soils and waters, as ecologically, economically and energetically sustainable remediation methods.Poslednjih 20 godina intenzivna upotreba metil tercijarnog butil etra (MTBE) dovela je do povećanja njegovog prisustva u čovekovoj sredini. Agencija za zaštitu čovekove sredine (EPA) okarakterisala je MTBE kao potencijalno kancerogeno jedinjenje i predložila metode za njegovo uklanjanje iz prirodnih sredina. Bioremedijacija predstavlja svetski trend u razvoju tehnologija remedijacije i sastoji se od kompleksa procesa koji podrazumevaju korišćenje različitih vrsta mikroorganizama. Mikroorganizmi su, zahvaljujući svojim fermentnim sistemima, sposobni da koriste različita organska jedinjenja kao jedinstven izvor ugljenika i energije i transformišu ih do netoksičnih produkata. Cilj rada bio je ispitivanje degradacije različitih koncentracija MTBE-a (76, 100, 438 i 746 ppm) pomoću Mucor hiemalis 139ž. Ovaj izolat izolovan je iz zemljišta NIS Rafinerije nafte Pančevo, kontaminiranog organskim zagađivačima. Proces degradacije praćen je u toku 8 dana inkubacije pri aerobnim uslovima. Degradacija MTBE-a praćena je pomoću gasnog hromatografa sa plamen jonizujućim detektorom (GC/FID). Posle 12 sati inkubacije došlo je do smanjenja koncentracije MTBE-a. Stepen degradacije MTBE-a posle 8 dana se kretao u intervalu od 47-76% od početne koncentracije. Stepen degradacije zavisio je od početne koncentracije MTBE-a. Ovi rezultati ukazuju na mogućnost primene autohtonog izolata Mucor hiemalis 139ž u procesima bioremedijacije zemljišta i voda, kao ekološki, ekonomski i energetski prihvatljiv metod remedijacije

Soja i mešane bakterijske populacije

The beneficial effect of soybean inoculation with bradyrhizobia is well known. The aim of this research was to determine the effect of inoculation of soybean seed with mixed population of Bradyrhizobium japonicum. Bacillus megaterium, Bacillus circulons, and Azotobacter chroococcum, on the number of microorganisms and yield of soybean. The experiment was conducted on chernozem at the experimental field of Maize Research Institute, Zemun Polje. Soybean seeds were inoculated before seeding. Bacterial mixture has contained equal amounts of the bacteria in the peat. Humate is added to peat in order to prolong bacteria survive. The control variant was inoculated with Bradyrhizobium japonicum. The study showed that seed inoculation with bacterial mixtures caused an increase in microbial activity in the soil rhizosphere (total bacterial number, number of ammonifiers, azotobacters and dehydrogenase). The highest yield of soybean was obtained by inoculation with B. japonicum, B. megaterium and Bacillus circulons (4.5tlha).Povoljan efekat inokulacije soje kvržičnim bakterijama odavno je poznat. Cilj ovih istraživanja bio je determinisanje efekta inokulacije semena soje mešanim populacijama Bradyrhizobiumjaponicum, Bacillus megaterium, Bacillus circulons i Azotobacter chroococcum na brojnost mikroorganizama i prinos soje. Ogled je postavljen na černozemu na oglednim poljima Instituta za kukuruz Zemun Polje. Seme soje je inokulisano neposredno pre setve. Bakterijske smeše sadržale su podjednake količine bakterija u tresetu. Humat je dodat tresetu radi stimulacije rasta bakterijskih populacija. Kontrolna varijanta bila je inokulisana sa Bradyrhizobium japonicum. Ispitivanja su pokazala da inokulacija semena bakterijskim smešama povećava mikrobiološku aktivnost zemljišne rizosfere (ukupan broj bakterija, amonifikatori azotobakter i dehidrogenaza). Najveći prinos soje dobijen je pri inokulaciji sa B. japonicum, B. megaterium i Bacillus circulons (4.5t/ha)

Filamentous fungi isolated from grape marc as antagonists of Botrytis cinerea

In this paper we report on the isolation and identification of three filamentous fungi from grape marc, and antifungal effect of their cell-free culture filtrates on the growth of Botrytis cinerea, causal agent of gray mold. Grape marc is a waste material that has been used as soil amendment in sustainable agriculture. Isolates originating from grape marc were identified on the basis of morphological features and internal transcribed spacer rDNA or β-tubulin gene sequencing. The presence of three different species, Penicillium paneum, Penicillium chrysogenum and Aspergillus fumigatus has been detected expressing different effect on the growth of B. cinerea. The effect of crude culture filtrates of selected fungi on B. cinerea growth was tested. Heat sensitivity of the established inhibition effect was examined by autoclaving the crude culture filtrate prior to testing. Additional aim was to determine whether antifungal effect was influenced by previous exposure to B. cinerea in dual liquid cultures. Crude culture filtrate of A. fumigatus K16/2 showed the lowest suppression of B. cinerea growth. A maximal percentage inhibition achieved within the study was 38.2%, 39.8% and 23.8 for crude filtrates of P. paneum K7/1, P. chrysogenum K11/1 and A. fumigatus K16/2, respectively. Presence of B. cinerea in dual liquid culture induced significant increase in antifungal capacity of the culture filtrates in comparison to pure culture filtrates of the chosen isolates. The antifungal activity of all of the isolates’ culture filtrates retained after heat treatment suggesting the presence of some thermostable antifungal metabolites. The results indicate the complexity and specificity of the interaction between filamentous fungi and B. cinerea. Grape marc is a good source for isolation od B. cinerea fungal antagonists and their antifungal metabolites. Specificity of fungal-fungal interactions suggests that further research on the antagonistic mechanisms and factors affecting them should be studied separately for each pair of antagonists. [Projekat Ministarstva nauke Republike Srbije, br. TR 31080 and III 43001, i FP7 Project AREA 316004

Isolation and characterization of bacteria and yeasts from contaminated soil

Plant growth promoting (PGP) bacteria and yeasts play an important role in bioremediation processes. Thirty bacterial and ten yeast isolates were obtained from PAH and PCB contaminated soil with an aim of determining the presence of PGP mechanisms (production of ammonia, indoleacetic acid, siderophores and solubilization of inorganic phosphate). As a result, three bacterial (Serratia liquefaciens, Micrococcus sp. and Serratia sp.) and two yeast isolates (Candida utilis and Candida tropicalis) were recognized as PGP strains. Among them, Serratia sp. showed the highest indole production (25.5 μg/ml). Analyses of metal tolerance (Cu+2, Cr+6 and Ni+2) revealed that Serratia liquefaciens, Micrococcus sp., Serratia sp. and Candida tropicalis were capable to tolerate significant concentration of metals. As a result of this study several bacterial and yeast strains were attributed as potential plant growth promoters which can be applied in future remediation activities and environmental quality improvements. [Projekat ministarstva nauke Republike Srbije, br. TR 31080 i FP-7 project AREA (316004)