Search

Increased soil salinity has numerous negative effects on plant growth and poses a significant threat to agricultural productivity worldwide. The diversity of endophytic bacterial communities found in various indigenous halophytes such as Salicornia europaea, Suaeda maritima, and Camphorosma annua, may reveal beneficial bacteria with various plant growthpromoting (PGP) properties. Members of Halomonas, the largest genus of the family Halomonadaceae, are rod-shaped, gram-negative, moderately halophilic bacteria that have been increasingly isolated from various saline environments, including halophyte tissues. As part of the halophytic microbiota, halotolerant plant growth-promoting endophytic bacteria can contribute to plant host growth, productivity, and fitness under abiotic and biotic stresses. The use of halotolerant PGP bacteria represents a good alternative strategy to mitigate the effects of salt stress in crops and to recover saline soils. The aim of this study was to isolate halotolerant bacteria from halophyte roots, and evaluate their PGP ability and their effect on germination parameters of selected crops. The endophytic bacterial communities in the roots of halophytes from natural saline soil in Slano Kopovo (Serbia) were analyzed using culture-dependent techniques. The genus Halomonas was the predominant among the halotolerant root-associated bacteria of analyzed halophytes. We have isolated seven Halomonas sp. strains, six of which were closely related (>99,86% similarity) to Halomonas songnenensis, a moderately halophilic bacterium from saline and alkaline soils. Obtained isolates were tested at different sodium chloride concentrations for a range of PGP traits at different concentrations of sodium chloride. The selected strains were used to inoculate seeds iand monitor of the germination process of barley, sunflower, and wheat under conditions of elevated salinity. Most of the isolates tolerate the NaCl concentration up to 18% and showed multiple PGP

Microbial degradation, compared with many other degradation processes, is the most important pathway for the depletion of triazine herbicides in soil. The aim of this study was to determine the growth potential of Pseudomonas sp. CY in the presence of atrazine and additional carbon (sodium citrate) and nitrogen (ammonium-nitrate) sources. The experiment was performed with five treatments: i) 100 mg/L atrazine (control); ii) One hundred mg/L atrazine + sodium citrate (0.3 %,w/v); iii) One hundred mg/L atrazine + sodium citrate (0.3 %, w/v) + ammonium nitrate (0.6 %, w/v);iv) Atrazine (300 mg/L) + sodium citrate (0.3 %, w/v) and v) Atrazine (500 mg/L) + sodium citrate (0.3 %, w/v). The bacterial count was determined after incubation (7 days at 30°C) using the agar plate method, while atrazine degradation was determined by measuring the optical density at 221 nm. Pseudomonas sp. CY can partially utilize atrazine as the sole source of carbon and energy. The highest values of the bacterial count were determined at the highest initial atrazine concentrations; however, bacterial growth was not detected in these treatments. A significant impact of citrate on bacterial growth and atrazine degradation was observed, while the addition of nitrate decreased the atrazine degradation rate. This study confirmed that Pseudomonas sp. CY can be used as a prominent candidate for the remediation of atrazine-affected environments.

Prikazano tehničko rešenje predstavlja inovaciju u obliku novog tehnološkog postupka – proizvodnje biofortifikatora na bazi Trichoderma spp. obogaćene selenom predviđenog za primenu u održivoj poljoprivredi. Primenom novog tehnološkog postupka dobijena je biomasa T. harzianum i T. citrinoviride gljiva sa visokim sadržajem selena, za biofortifikaciju prehrambenih useva u Republici Srbiji selenom, koja se smatra selenom deficitarnim područjem. Pri izboru gljiva u ovom tehničkom rešenju, vodilo se računa da se odaberu one gljive koje imaju biokontrolnu i ulogu u stimulaciji rasta biljaka, čijim obogaćenjem selenom je dobijen proizvod sa dodatom vrednošću. Dobijeni rezultati pokazuju da obogaćivanje biomase selenom u određenoj meri modifikuje odlike same gljive. T. harzianum i T. citrinoviride obogaćene selenom, u većini konfrontacijskih testova, zadržale su visoko antagonističko delovanje prema testiranim biljnim patogenima. Obogaćivanje biomase T. citrinoviride selenom dovelo je do porasta antagonističkog delovanja prema Botrytis sinerea. Zabeležen je i porast koncentracije indolsirćetne kiseline nakon obogaćivanja biomase selenom, što je značajan rezultat imajući u vidu ulogu indolsirćetne kiseline u rastu i razvoju biljaka.

Eksploatacija rude, i pored benefita za ljudsko društvo, dovodi do pogoršanja kvaliteta životne sredine. Kao posledica eksploatacije, dolazi do deponovanja otpadnog materijala i stvaranja jalovina sa nepovoljnim fizičkim, hemijskim i biološkim osobinama. Imajući u vidu značaj mikroorganizama u oštećenim ekosistemima, cilj ovog rada bio je ispitivanje mikrobnog diverziteta jalovine; na jednom delu jalovine izvršena je setva semena crvenog vijuka uz dodatak organskog i mineralnog đubriva (CVF), na drugom setva istog semena bez đubrenja (CV), dok je treći deo, bez setve i đubrenja, predstavljao kontrolu (KON). Mikrobni diverzitet ispitan je metodom agarnih ploča, pri čemu je određen ukupan broj bakterija, amonifikatora i gljiva, kao i prisustvo vrsta iz rodova Pseudomonas sp. i Azotobacter sp. Dobijeni rezultati ukazuju na nizak ukupan broj bakterija, amonifikatora i gljiva, dok vrste iz rodova Pseudomonas sp. i Azotobacter sp. nisu detektovane. Slaba zastupljenost mikrobnih populacija je posledica niskog sadržaja hranljivih supstanci i visoke koncentracije teških metala. Đubrenje je uticalo na povećanje mikrobiološke aktivnosti, kao i na promenu odnosa fungalnih i bakterijskih populacija, što ukazuje na oporavak oštećenog ekosistema.

Biopriming is a pre-sowing seed inoculation technique based on beneficial microorganisms. The aim of the study was to estimate biopriming potential of microbial consortium on soybean seeds. Obtained results showed a stimulative effect of biopriming resulting in 8% higher germination percentage. Inoculated seeds were characterised as more vigorous according to vigor I, vigor II and electrical conductivity results. Accelerated aging test decreased germination percentage of both treatments to approximately 66±2%. Inoculated seeds were marked as more vigorous according to vigor I index. Biopriming of soybean seeds resulted in an increase of germination parameters that suggest stimulative effects on seed quality.

One of the major problems in agriculture are Fusarium species which cause fusariosis in wheat, corn, tomato, melon, watermelon, onion, peas, and beans. Also, Fusarium can synthesize thermostable mycotoxins which can lead to certain diseases if they were found in food. Currently, chemical fungicides are mostly used to prevent the occurrence of fusariosis disease, but the resistance of pathogens to such treatment is being more and more widespread. Soil microorganisms help in plant defense and growth. The rhizosphere fungi have an important role in the mutual exchange of nutrients with plants and they can establish specific interactions with plants. Such rhizosphere fungi are known as plant growth-promoting (PGP). These PGP fungi affect the better plant growth through the synthesis of certain phytohormones but they also have the function as biocontrol agents. They can inhibit the growth of phytopathogens through direct mechanisms of antibiosis, mycoparasitism, and competition. The goal of this research was an investigation of the antagonistic effect of Trichoderma harzianum TR1 and Trichoderma citrinoviride 1V on Fusarium oxysporum and Fusarium graminearum. The antagonistic effect was examined through two tests: Dual culture test (DUAL test) and the effect of volatile organic compounds (VOCs) of Trichoderma strains on the growth of Fusarium strains. Also, the cell-wall degrading enzymatic activity of T. citrinoviride and T. harzianum was examined. The results showed that antagonistic activity of Trichoderma strains varies from moderate to high. Mycelial growth inhibition by T. citrinoviride was 44% for F. graminearum and 67% for F. oxysporum. T. harzianum inhibited F. gramminearum growth for 59% and F. oxysporum for 66%. Based on the results, it was concluded that T.harzianum and T.citrinoviride can be considered biocontrol agents for F. oxysporum and F. graminearum.

This study assesses the effects of Azotobacter biopriming on the early development of sugar beet. Azotobacter chroococcum F8/2 was screened for plant growth promoting characteristics and biopriming effects were estimated through germination parameters and the structural changes of the root tissues. A. chroococcum F8/2 was characterized as a contributor to nitrogen, iron, and potassium availability, as well as a producer of auxin and 1-aminocyclopropane-1-carboxilic acid deaminase. Applied biopriming had reduced mean germination time by 34.44% and increased vigor I by 90.99% compared to control. Volatile blend comprised 47.67% ethanol, 32.01% 2-methyl-propanol, 17.32% 3-methyl-1-butanol, and a trace of 2,3-butanedione. Root micromorphological analysis of bioprimed sugar beet revealed a considerable increase in primary, secondary xylem area, and vessels size. Obtained results determine A. chroococcum F8/2 as a successful biopriming agent, and active participant in nutrient availability and hormonal status modulation affecting root vascular tissue. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

Different priming methods were developed to improve seed germination and the early growth of seedlings. This study aimed to examine the combined effect of bacterial inoculation and static magnetic field on white mustard (Sinapis alba L.) germination. A plant growth‐promoting bacterial strain Bacillus amyloliquefaciens D5 ARV was used for biopriming. The static magnetic field of 90 mT was applied for 5 and 15 min. Analyses of abscisic acid, chlorophyll, anthocyanins, flavonoids content, nitrogen balance index, and bacterial indole‐3‐acetic acid were used to explain observed effects. Bacterial inoculation improved seed germination, whereas exposure to 90 mT for 15 min suppressed germination. Such an unfavorable effect was neutralized when the treatment with the static magnetic field was combined with bacterial inoculation. The highest germination percentage was a result of synergistic action of B. amyloliquefaciens D5 ARV and 15 min long exposure to 90 mT, which induced an increase of 53.20% in the number of germinated seeds. The static magnetic field induced the increase of bacterial indole‐3‐acetic acid production threefold times. Biomagnetic priming caused a metabolic shift from primary to secondary metabolism in the white mustard seedlings. An adequate combination of biological priming and static magnetic field treatment can be successfully used in old seed revitalization and germination improvements.

Crop yields are highly depended on germination and early stages of plant growth. Numerous priming techniques are being developed aimed to improve germination. Biopriming represents a sustainable approach based on seed treatment in bacterial suspension of selected plant growth promoting strains. One of the most promising plant growth promoting bacteria is Azotobacter chroococcum. The aim of the research was to evaluate the effects of A. chroococcum F8/2 as a biopriming agent on germination of various cultivable plants: basil, white mustard, cucumber, tomato, wheat, canola, and soybean. After surface sterilization, seeds were bioprimed in the bacterial suspension (107CFU/ml). Uninoculated seeds represented control treatment. Germination test was conducted with 100 seeds per treatment and the germination was monitored for 7 days. Following germination parameters were determined: germination percentage, germination index, mean germination time, vigor I, vigor II, length and dry biomass of the seedlings. The bacterial inoculation caused higher germination percentages of cucumber, tomato, wheat and soybean. The highest increase in germination index was observed in wheat (an increase of 19.8%). Tomato and basil were the only plants where vigor I was not increased by inoculation. Generally, the most favorable effects of A. chroococcum biopriming were observed in wheat where vigor I was increased more than twice, and vigor II was higher by 75.4% in inoculated seeds. The results indicate a significant potential for A. chroococcum use in biopriming. The observed effects of seed priming on germination parameters were crop-specific, with the most prominent potential in wheat biopriming.

Good microbiological quality of irrigation water has a great importance for health-safety agricultural production. In order to avoid microbiological contamination of crops, the microbiological quality of the water supplying the crops should be monitored. The aim of this paper is investigation of the microbiological quality of the water from 5 channels and one pool from the municipality of Surcin which can potentially be used for irrigation, as well as determination the microbiological quality of the vegetables which are irrigated from the pool. Microbiological parameters of water and vegetables quality are determined by the standard methods prescribed by the Rulebook on parameters of surface waters (MPN method) and Rulebook of food hygiene of production of Republic of Serbia. The values of the tested parameters in one of the five investigated channels, Surcin channel water, were higher in relation to the limit values of the Rulebook. The increased levels of total and fecal coliforms, Escherichia coli, Salmonella, and Shigella were found. The Surcin channel water requires appropriate treatment before its use for crop irrigation. The values of other tested waters did not go beyond the limit values prescribed by the Rulebook, but for the safer agricultural production their treatment is recommended. Microbiological analyzes of vegetables were also done. The total and fecal coliform bacteria, as well as E. coli, Salmonella sp. and Shigella sp., were not detected in the tested vegetable samples.

Surface mining activities, despite their benefits, lead to the deterioration of local and regional environmental quality and play a role in global ecosystem pollution. This research aimed to estimate the culturable microbial population structure at five locations near the opencast coal mine “Kakanj” (Bosnia and Herzegovina) via agar plate and phospholipid fatty acids (PLFA) method and to establish its relationship to the physical and chemical properties of soil. Using the ICP-OES method, the heavy metal pollution of all examined locations (overburden, former grass yard, forest, arable soil, and greenhouse) was observed. Substantial variations among the sites regarding the most expressed indicators of heavy metal pollution were noted; Cr, Pb, Ni, and Cu content ranged from 63.17 to 524.47, 20.57 to 349.47, 139.13 to 2785.67, and 25.97 to 458.73 mg/kg, respectively. In the overburden sample, considerable low microbial activity was detected; the bacterial count was approximately 6- to 18-fold lower in comparison with the other samples. PLFA analysis showed the reduction of microbial diversity, reflected through the prevalence of normal and branched saturated fatty acids, their ratio (ranged from 0.92 to 7.13), and the absence of fungal marker 18:2ω6 fatty acid. The principal component analysis showed a strong negative impact of heavy metals Na and B on main microbial and PLFA profiles. In contrast, stock of main chemical parameters, including Ca, K, Fe, and pH, was positively correlated with the microbial community structure.

Red clover (Trifolium pratense L.) seeds were inoculated with several plant growth-promoting bacteria (PGPB) and sown in the substrate contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organometallic derivatives of tin (OT). The aim was to determine if selected PGPB strains can promote the growth of red clover in the substrate contaminated with several organic pollutants. The influence of bacteria on red clover growth (height, root length and biomass) was monitored during the three-month experimental period. The most significant improvements of seedling height were noted in the treatment with Bacillus amyloliquefaciens D5 ARV and Pseudomonas putida P1 ARV. Root growth was positively affected by Serratia liquefaciens Z-I ARV. The same isolates significantly affected biomass production. Those isolates caused total biomass increases of 70%, 48% and 33% compared to control. Bacterial strains used in this study were already confirmed as PGPB by biochemical testing, as well as by an in vivo test of mixed inoculums on several woody plants grown in the coal-mine overburden site. This work is the first-time record on their individual effects on one plant species. Obtained results confirmed that inoculation with several PGPB strains can enhance red clover growth in polluted soil., Seme crvene deteline (Trifolium pratense L.), inokulisno sa nekoliko bakterija stimulatora biljnog rasta (PGPB), posejano je u supstrat kontaminiran policikličnim aromatičnim ugljovodonicima (PAHs), polihlorovanim bifenilima (PCBs) i organometalnim derivatima kalaja (OT). Cilj je bio da se utvrdi da li selektovane PGPB mogu promovisati rast crvene deteline u supstratu kontaminiranom sa nekoliko organskih zagađujućih materija. Uticaj bakterija na rast crvene deteline (visina, dužina korena i biomasa) praćen je tri meseca. Najveća visina je zabeležena kod biljaka inokulisanih sa Bacillus amyloliquefaciens D5 ARV i Pseudomonas putida P1 ARV. Rast korena je stimulisan od strane Serratia liquefaciens Z-I ARV. Ovi izolati su značajno uticali i na produkciju biomase. Ukupna biomasa dobijena tokom celog ogleda je za 70%, 48% i 33% veća u odnosu na kontrolu. Bakterijski sojevi korišćeni u ovoj studiji su prethodno potvrđeni kao PGPB kroz biohemijske i in vivo testove mešanog inokuluma na nekoliko drvenastih vrsta gajenih u jalovini. Ovaj rad prvi put beleži njihove pojedinačne efekte na jednu biljnu vrstu. Dobijeni rezultati potvrđuju da inokulacija sa nekoliko PGPB sojeva može ubrzati rast crvene deteline u zagađenom zemljištu.

BACKGROUND Determination of the halophytic microbiome diversity is the basis for understanding the mechanisms that enable halophytes to tolerate the increased salt concentration. This report provides new data regarding the bacterial halophyte community and diversity of the endorhizosphere of the halophytic Hordeum hystrix Roth. Hordeum hystrix Roth. (Poaceae) is an annual plant of seasonally flooded saline lands and consequently, plant samples were collected from the area of the naturally formed saline lands, Slano Kopovo. OBJECTIVES In addition to the analysis of microbiome diversity, the aim of this study was to characterize isolates of halophilic endophytic bacteria and their plant growth promoting ability. METHODS The metagenomic approach based on 16s rRNA gene sequencing was used to gain insight into the composition of the endophyte bacterial community at different taxonomic levels. The endophytic isolates were initially selected for the maximum salt concentration tolerance and the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. Selected strains were tested on eight PGP traits at different NaCl concentrations. RESULTS Most isolates could tolerate the NaCl concentration over a range from 3-20%. Two strains showed positive results related to all eight tested PGP traits. At the high NaCl concentrations, the same strains retained seven positive PGP features. Our results indicate that the endorhizosphere of the halophytes is a source of halophilic PGP bacteria that, in addition to its beneficial effects on the host, have the possibility of their potential application in sustainable agriculture.

Hexavalent chromium, Cr(VI), one of the major pollutants from industrial facilities, is very toxic and harmful for human health and environmental quaky. Due to the lack of conventional methods, bioremediation was recommended as an environmentally friendly and effective technique. The aim of this paper was the isolation, identification and selection of the microorganisms which are capable of Cr(VI) reduction in vitro. Heavy metal concentration, detected in four soil samples, within and around the former bicycle factory Wog" (Republic . of Slovenia), was measured using the ICP-OES method. Bacteria were isolated and tested for chromium tolerance using LB agar supplemented with various Cr(VI) concentrations, whilst Cr(VI) reduction and bacterial growth was determined using the LB liquid medium. From 53 bacterial isolates, five of them showed a tolerance of 1000 mg/L of Cr(VI). Those five isolates showed the capability of growth under various Cr(VI) concentrations (50-1000 mg/L). Initial Cr(VI) concentrations ranging from 50 to 100 mg/L were completely reduced by four bacterial isolates, whilst 500 to 1000 mg/L by Bacillus safensis 342-9. Using 16S rDNA and tuf gene sequence analyses, isolates 270-9R and 342-9 were identified as Bacillus safensis, isolates 351-9 and 270-9C as Bacillus subtilis subsp. subtilis, and 212-9 as Bacillus thuringiensis. These results indicated that these bacteria may be promising tools for remediation of metal-polluted sites.

Mnogobrojne industrijske aktivnosti, osim koristi za ljudsku populaciju, imale su za posledicu povećanje sadržaja teških metala i promene diverziteta živih organizama u životnoj sredini. Cilj ovog rada bio je ispitivanje uticaja visokih koncentracija teških metala na mikrobni diverzitet zemljišta i mogućnosti primene ekoremedijacionih tehnologija u cilju saniranja posledica industrijske aktivnosti. Istraživanja su obavljena na području bivše fabrike “Rog” (Ljubljana, Republika Slovenija). Ispitivanje mikrobnog diverziteta obavljeno je primenom standardnih metoda. Rezultati istraživanja ukazuju da je brojnost hrom-rezistentnih bakterija i gljiva bila različita i zavisila je od koncentracije hroma u podlozi, pH vrednosti podloge i lokacije uzorkovanja. Iz kontaminiranih uzoraka zemljišta, ukupno su izolovana 53 izolata hrom-rezistentnih bakterija. Među njima dominiraju gram-pozitivne štapićaste sporogene bakterije. Morfološkom i molekularnom identifikacijom bakterijski izolati su svrstani u rod Bacillus sp. Rast hrom-rezistentnih gljiva je zavisio od istih faktora kao i kod hrom-rezistentnih bakterija. Gljive su morfološki identifikovane i svrstane u rodove Alternaria sp., Fusarium sp. i Penicillium sp. Stepen redukcije Cr(VI) zavisio je od njegove početne koncentracije, bakterijskih izolata i vremena inkubacije. Svi bakterijski izolati su bili sposobni za kompletnu ili delimičnu redukciju različitih početnih koncentracija Cr(VI). Precizno morfološki okarakterisane i molekularno identifikovane mikrobne populacije u interakciji sa biljkama tolerantnim na prisustvo metala, predstavljaju nezamenljive karike bioremedijacionih tehnologija. Rezultati ove doktorske disertacije imaju, osim naučnog, i aplikativni značaj i mogu se primeniti u remedijaciji zemljišta kontaminiranih industrijskim otpadom., The numerous industrial activities, except of the benefits for the human population, resulted in an increase in the content of heavy metals and a change in the diversity of living organisms in the environment. The aim of this disertation was to examine the influence of high concentrations of heavy metals on the microbial diversity of the soil and the possibility of applying ecoremediation technologies in order to remedy the consequences of industrial activity. The research was carried out on the location of the former factory "Rog" (Ljubljana, Republic of Slovenia). Examination of microbial was carried out with using of standard methods. The results of the study indicate that the number of chromium-resistant bacteria and fungi was different and it depended on the concentration of chromium in the substrate, substrate pH and sampling location. From contaminated soil samples, 53 isolates of chromium-resistant bacteria were isolated. Among them, gram-positive rod-shaped spore-forming bacteria dominate. By morphological and molecular identification, bacterial isolates are classified into the genus Bacillus sp. The growth of chromium resistant fungi depend on the same factors as for chromium-resistant bacteria. Fungi have been morphologically identified and classified into the genus Alternaria sp., Fusarium sp. and Penicillium sp. The degree of reduction Cr (VI) depended on its initial concentration, bacterial isolates and incubation times. All bacterial isolates were capable of complete or partial reduction of different initial concentrations of Cr (VI). Precisely morphologically characterized and molecularly identified microbial populations interacting with plants tolerant to the presence of metals are irreplaceable players in bioremediation technologies. The results of this dissertation have scientific and applicative significance, and can be applied in the remediation of soil contaminated with industrial waste.