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Characteristics of rhizobacteria in potential hyperaccumulator vegetation and their resistance to gold mine tailing stress

Aminatun Tien, Rakhmawati Anna, Atun Sri, Idrus Arifudin, Simbolon Doly Risdo, Restele Laode

Journal of Water and Land Development

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2024

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no. 60

209--218

EN

The use of local bacteria is preferred in bioleaching as an environmental-friendly alternative technology in gold mining. In a preliminary study, rhizobacteria were isolated and cultured from three types of hyperaccumulator vegetation from the Ratatotok gold mine, Indonesia, namely Pteris vittata L., Syzygium aromaticum L., and Swietenia mahagoni Jacq. These rhizobacteria still need to be characterised and identified. This study is aimed to cover bacterial phenotypic characterisation, assessment of bacteria resistance to tailing, and identification of bacterial strains the exhibit the highest resistance to tailings. The assessment was carried out across a spectrum of tailing concentrations, selecting the three most robust strains for molecular identification. The process involved genotypic characterisation to determine the species name by analysing the 16S rRNA gene. The results reveal that the phenotypic characteristics of the bacteria isolates vary, but all of them are the indole acetic acid (IAA) hormone producers. The highest IAA producer is the isolate from the rhizosphere of S. aromaticum. Based on the genotypic characterisation test, three most resistant isolates to tailing stress are the following strains Pseudomonas aeruginosa (RTKP1) and Stenotrophomonas geniculata (RTKP2), both from the rhizosphere of P. vittata; as well as Bacillus cereus (RTKS) from the rhizosphere of S. aromaticum. These three strains need to be further tested for their bioleaching capability to recover gold from tailings. Additionally, this study recommends that gold recovery using biological agents can combine the role of hyperaccumulator plants in phytomining and rhizobacteria in bioleaching.

2

Biological Control as an Alternative Method of Protecting Crops Against Fungal Pathogens

Kisiel Anna

Rocznik Ochrona Środowiska

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2019

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Tom 21, cz. 2

1366--1377

EN

Progressive degradation of the environment caused, among others, by the excessive use of chemical pesticides forces us to look for alternative methods of protecting crops against pathogens. Definitely beneficial for the environment, but also, as confirmed by numerous studies, the use of biological control mechanisms can be an effective solution. The bacteria can inhibit the growth of fungi through the production of enzymes that lyse their cell walls, such as chitinases and glucanases, but also by limiting the availability of microelements important to growth, such as iron, by chelating them to siderophores, and finally producing antibiotics and secondary metabolites, like 2,4-DAPG. The present study examined 16 strains of bacteria isolated from Medicago sativa rhizosphere for their suitability for the control of fungal pathogens such as Fusarium culmorum and Phoma medicaginis. Among of bacteria were strains belonging to the family Bacillaceae (genus Bacillus, Lysinibacillus and Paenibacillus), the family Pseudomonadaceae (genus Pseudomonas), the family Xantomonadaceae (genus Stenotrophomonas) of the Enterobacteriaceae family (genus Citrobacter, Leclercia and Raoultella) and of the family Rhizobiaceae (genus Sinorhizobium). In vitro, both on solid and liquid media, all bacterial strains were able to limit the growth of Fusarium culmorum and Phoma medicaginis. The effective inhibitors of Fusarium culmorum Cul-3 were Roultella planticola KK 8a, Pseudomonas corrugata KK 12, and both strains belonging to Stenotrophomonas maltophilia KK 8b and KK 9b. Limiting the development of the second Medicago pathogen, Phoma medicaginis, was the most effective after the use of Pseudomonas corrugata KK 7, Leclercia adecarboxylata KK 6 and Pseudomonas brassicacearum KK 5. By studying the mechanisms that may be potential for bacteria to inhibit the growth of fungi was tested production of lytic enzymes the cell walls, and siderophores. All bacterial strains showed β-1,3-glucanase activity in the range of 2.3 to 72.5 μmol glucose /mg protein/min. Five strains showed chitinolytic activity, with Stenotrophomonas maltophilia KK 8b being the most active. Thirteen of the 16 analyzed strains of rhizobacteria were able to produce iron chelating compounds, siderophores. In addition, the presence of the phlD gene was confirmed in Pseudomonas brassicacearum KK 5 and P. corrugata KK 12, which may indicate the production of 2,4-DAPG. The results obtained indicate that the bacteria isolated from the rhizosphere have the potential for biological control of fungal pathogens, which limit the plant cultivation, using various mechanisms. The use of rhizobacteria as biopesticides is an environmentally friendly alternative to chemical plant protection products.

PL

Postępująca degradacja środowiska spowodowana między innymi nadmiernym wykorzystywaniem chemicznych środków ochrony roślin zmusza nas do poszukiwania alternatywnych metod zabezpieczania upraw przed patogenami. Zdecydowanie korzystnym dla środowiska ale również, jak potwierdzają liczne badania, skutecznym rozwiązaniem może być wykorzystanie mechanizmów zwalczania biologicznego. Bakterie mogą ograniczyć rozwój patogenów grzybowych poprzez produkcję enzymów lizujących ich ściany komórkowe, takich jak chitynazy i glukanazy ale także poprzez ograniczenie dostępności ważnych dla ich wzrostu mikroelementów, jak żelazo, chelatując je do sideroforów, czy wreszcie produkując grzybobójcze antybiotyki i metabolity wtórne, jak 2,4-DAPG.W niniejszych badaniach przeanalizowano 16 szczepów bakterii wyizolowanych z ryzosfery Medicago sativa pod kątem ich przydatności do zwalczania patogenów grzybowych takich jak Fusarium culmorum i Phoma medicaginis. Wśród bakterii były szczepy należące do rodziny Bacillaceae (rodzaju Bacillus, Lysinibacillus i Paenibacillus), z rodziny Pseudomonadaceae (rodzaju Pseudomonas), z rodziny Xantomonadaceae (rodzaju Stenotrophomonas), z rodziny Enterobacteriaceae (rodzaju Citrobacter, Leclercia i Raoultella) oraz z rodziny Rhizobiaceae (rodzaju Sinorhizobium). W warunkach in vitro zarówno na pożywkach stałych jak i płynnych wszystkie analizowane szczepy bakterii były zdolne do ograniczenia wzrostu Fusarium culmorum oraz Phoma medicaginis. Do skutecznych inhibitorów rozwoju Fusarium culmorum Cul 3 należy zaliczyć szczepy Roultella planticola KK 8a, Pseudomonas corrugata KK 12, oraz oba szczepy należące do Stenotrophomonas maltophilia KK 8b i KK 9b. Ograniczenie rozwoju drugiego patogena Medicago, tj. grzyba Phoma medicaginis było najskuteczniejsze po zastosowaniu szczepów Pseudomonas corrugata KK 7, Leclercia adecarboxylata KK 6 i Pseudomonas brassicacearum KK 5. Badając mechanizmy, które mogą stać za potencjałem bakterii do hamowania wzrostu grzybów sprawdzono produkcję enzymów lizujących ściany komórkowe oraz sideroforów. Wszystkie szczepy bakterii wykazywały aktywność β-1,3-glukanazy w zakresie od 2,3 do 72,5 μmol glukozy/mg białka/min. Pięć szczepów wykazało aktywność chitynolityczną, największą aktywnością charakteryzował się szczep Stenotrophomonas maltophilia KK 8b. Trzynaście z 16 analizowanych szczepów ryzobakterii było zdolnych do produkcji związków chelatujących żelazo, sideroforów. Ponadto u Pseudomonas brassicacearum KK 5 i P. corrugata KK 12 potwierdzono obecnośc genu phlD, co może świadczyć o produkcji 2,4-DAPG. Jak wynika z przeprowadzonych badań bakterie izolowane z ryzosfery posiadają potencjał do zwalczania patogenów grzybowych ograniczających uprawy, wykorzystując do tego szereg mechanizmów. Zastosowanie ryzobakterii jako biopestycydy jest przyjazną dla środowiska alternatywą dla chemicznych środków ochrony roślin.

3

Growth and heavy metals uptake by Vicia faba in mining soil and tolerance of its symbiotic rhizobacteria

El Alaoui Abdelkhalek, Bechtaoui Noura, Benidire Loubna, El Gharmali Abdelhay, Achouak Wafa, Daoui Khalid, Imziln Boujamaa, Oufdou Khalid

Environment Protection Engineering

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2019

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Vol. 45, nr 1

83--96

EN

Faba bean plants in the 1/8 mixture with soil had the ability to accumulate Pb, Zn and Cu. 95% of the absorbed Pb were in the roots, and Cu and Zn were found in the shoots by 35% and 45%, respectively. There was a decrease in the root hairs and the number of cell layers of the root cortex alongside epidermis lesions. From the 50 tested rhizobacterial strains, 20 were able to grow at 150 mg/dm3 of Pb, 6 were resistant to 150 mg/dm3 of Zn and 8 resisted to 20 mg/dm3 of Cu. Best four strains had adsorption potentials and the biosorption was higher for Cu. These strains were capable of producing auxin and exopolysaccharides. The most tolerant strains (FD1 and FD2) isolated near the mining site produced siderophores and high amounts of exopolysaccharides. The use of such strains and V. faba could be of important biotechnological value in decreasing heavy metal pollution of mining soils.

4

Selekcja bakterii ryzosferowych usprawniających procesy fitoremediacji gleb zawierających związki metali ciężkich

Dąbrowska G., Hrynkiewicz K., Kłosowska K., Goc A.

Ochrona Środowiska

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2011

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Vol. 33, nr 2

53-58

PL

Wiele spośród bakterii ryzosferowych charakteryzuje się wysoką opornością na jony metali ciężkich i odgrywa ważną rolę w promowaniu wzrostu roślin w ich obecności. W badaniach przeanalizowano szczepy bakterii Bacillus sp. (ML 1-2), Bacteroidetes bacterium (RI 116-1), Flavobacterium sp. (RI 111-11), Pseudomonas fluorescens (LI C1), Serratia entomophila (RI 111-21) i Variovorax sp. (ML 3-12), wyizolowane z gleb skażonych związkami metali ciężkich lub zdegradowanych antropogenicznie. W warunkach in vitro wyselekcjonowano bakterie oporne na jony wybranych metali ciężkich (Cd, Cu, Zn i Pb). Wykazano, że S. entomophila (RI 111-21) i P. fluorescens (LI C1) należą do bakterii o najwyższym stopniu oporności na obecność jonów metali ciężkich w podłożu, zwłaszcza cynku i ołowiu. Szczepami o najwyższej wrażliwości na przeanalizowane jony metali cięż-kich okazały się B. bacterium (RI 116-1) i Flavobacterium sp. (RI 111-11). Stwierdzono, że na wzrost i rozwój siewek rzepaku negatywnie wpływały jony metali ciężkich uszeregowane w kolejności: Pb>Zn>Cu>Cd. Inokulacja rzepaku ozimego (Brassica napus L. odmiana Kronos) wykazała, że niektóre bakterie promowały wzrost i rozwój siewek w obecności jonów metali ciężkich, zwłaszcza miedzi i kadmu. Szczepy Bacillus sp. (ML 1-2) i B. bacterium (RI 116-1) najsilniej promowały wzrost siewek rzepaku w środowisku zawierającym jony metali ciężkich, stąd też wydają się mieć największy potencjał w procesach fitoremediacji gleb.

EN

Many soil bacteria show a high tolerance to heavy metals and play a vital role in promoting plant growth in a heavy-metal-contaminated environment. In the study reported on in this paper the bacterial strains being analyzed included Bacillus sp. (ML 1-2), Bacteroidetes bacterium (RI 116-1), Flavobacterium sp. (RI 111-11), Pseudomonas fluorescens (LI C1), Serratia entomophila (RI 111-21), and Variovorax sp. (ML 3-12), which had been isolated from soils contaminated by heavy metal compounds, or degraded due to anthropogenic activity. Under in-vitro conditions selected were bacteria tolerant to Cd, Cu, Zn and Pb. It has been demonstrated that among the strains examined S. entomophila (RI 111-21) and P. fluorescens (LI C1) are endowed with the highest tolerance to the heavy metals in the substrate, specifically to Zn and Pb, whereas B.?bacterium (RI 116-1) and Flavobacterium sp. (RI 111-11) display the highest vulnerability to heavy metals. Taking into account their negative influence on the growth and development of rape seedlings, the four heavy metals have been listed in the following order: Pb>Zn>Cu>Cd. Inoculation of winter rape (Brassica napus L. var. Kronos) has shown that some of the bacterial strains promote the growth and development of seedlings in the presence of heavy metals, especially copper and cadmium. The strains Bacillus sp. (ML 1-2) and B. bacterium (RI 116-1), which were parti-cularly active in promoting rape seedling growth in an environment containing heavy metals, seem to have the greatest potential for the phytoremediation of soils.

5

The application of plant growth promoting rhizobacteria (PGPR) in low input and organic cultivation of graminaceous crops; potential and problems

Cummings S. P.

Environmental Biotechnology

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2009

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Vol. 5, No. 2

43-50

EN

Although the uses of plant growth stimulating bacteria (PGPR) to improve the yield of graminaceous crops have been studied for over seventy years the utility of the technology remains uncertain. Increases in crop yield have often been inconsistent, reflecting a lack of understanding of the mechanisms by which PGPR exert their effects. Because PGPR are able to fix N2, this was initially assumed to boost crops by supplementing soil N. However, it is now clear, that for most free living PGPR, other mechanisms affecting root development, and nutrient uptake can account for the observed increase in crop yields. Here we review the current state of our understanding of PGPR in graminaceous crop cultivation, identifying their potential contribution to more sustainable agricultural practices but also highlighting issues that need to be addressed before this technology can be appropriately assessed as a replacement for inorganic N addition.