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The objective of this research was to isolate bacteria belonging to the genus Bacillus from the nettle rhizosphere, conduct biochemical and plant-growth-promoting (PGP) characterization of isolates, and examine their biostimulatory effects on the seeds of medicinal plants. Microorganisms were isolated using the agar plate method for bacterial isolation. Biochemical characterization involved evaluating the isolates’ ability to produce enzymes such as lipase, amylase, pectinase, protease, cellulose, urease and gelatinase. Plant-growth-promoting (PGP) characterization included evaluation of indole-3-acetic acid (IAA), siderophore and hydrogen cyanide (HCN) production, as well as the ability to mineralize organic phosphorus compounds and solubilize phosphate. The impact of isolates on seed germination and plant growth was studied using summer savory (Satureja hortensis L.) and parsley (Petroselinum crispum L.) seeds. The experiment was conducted under laboratory conditions. The number of germinated seeds, the shoot and root length of seedlings, vigor index and root and shoot length of the plant were measured. According to the morphological description of the colony and cells, five Bacillus bacteria (denoted as Bac4, Bac5, Bac6, Bac7, Bac8) were selected for further examination. All isolates showed good PGP potential. The isolates that stand out are isolates Bac5, Bac7 and Bac8. The best effect on the seed germination was exerted by B5 and Bac8 isolates. Isolates Bac7 and Bac8 had the greatest stimulatory effect on seedling and plant growth. Having great PGP traits, these isolates may represent a biological alternative for the application of harmful pesticides and chemical fertilizers in the production of summer savory and parsley.

The significance of employing Plant Growth Promoting (PGP) microorganisms holds immense value in the cultivation of medicinal plants, where the attainment of high-quality plant biomass is indispensable. Therefore, it becomes imperative to isolate and identify a diverse array of microorganisms from the rhizosphere of various plants and assess their efficacy in enhancing the growth of medicinal plants. The primary aim of this research was to isolate and characterize bacteria belonging to the Bacillus, Streptomyces, and Azotobacter genera from the rhizosphere of nettle (Urtica dioica L.). Additionally, the study explored the influence of the bacterial isolates on the germination of oregano (Origanum vulgare L.) and marjoram (Origanum majorana L.) seeds. Isolation, physiological characterization (the growth of isolates at different temperatures, levels of acidity and concentrations of NaCl, and resistance of isolates to Cd and Pb), biochemical characterization (the production of lipase, amylase, pectinase, and cellulase), and PGP characterization of isolates were performed. The impact of isolates on seed germination was monitored under controlled conditions. The count of sprouted seeds was assessed at 7-and 10-day intervals. The results of this study reveal that the isolated rhizospheric bacteria of nettle have multiple physiological, biochemical and PGP properties. All isolates showed good PGP potential, but the isolates Azotobacter A1 and Streptomyces Ac1 stood out. The applied isolates had a positive effect on the seed germination of oregano and marjoram, the best effect being exhibited by Bacillus B2 and Azotobacter A1 on the seed germination of oregano and by Bacillus B1 and Streptomyces Ac1 on that of marjoram.

Having in mind food security and the fact that basil (Ocimum basilicum L.) is used as fresh seasoning, the development of innovative technologies for its cultivation is required. This study aimed to isolate and characterize plant growth-promoting rhizobacteria (PGPR) isolates from basil rhizospheric soil and monitor the effects of their application on basil growth under different water stress conditions. Isolation, determination of isolates biochemical and PGP properties, evaluation of isolates influences on seed germination and parameters of growth of basil plant, growing under well-watered conditions (70% water holding capacity, WHC), under water deficit stress (35% WHC), and flooded conditions (95% WHC), were done. A total of five representative bacterial isolates were selected: Two Azotobacter isolates (A13, A14), one Pseudomonas isolate (P57), and two Bacillus isolates (B79, B82). The results of this experiment revealed that rhizospheric bacteria of O. basilicum L. var. minimum have multiple biochemical and PGP properties. The most intensive reactions on tested abiotic stressors - drought (higher total phenolics, reduced glutathione, and malondialdehyde content) and flooding (higher superoxide dismutase activity) - were from basil plants inoculated with Pseudomonas sp. P57 isolate, yet along with Azotobacter sp. isolate A13. The highest number of germinated seeds was obtained with the A13 isolate (96.0%), while the highest response for vigour index was observed with Azotobacter isolates (7200.0% and 5628.0%). In well-watered conditions, basil mass inoculated with P57 was 34.2% higher than control. In drought-stressed conditions, plant mass inoculated with A13 isolate was 90% higher than control. In flooded-stressed conditions, the plant mass inoculated with Azotobacter and Pseudomonas isolates increased by more than 100%. [ABSTRACT FROM AUTHOR]

The objective of the present paper was to isolate microorganisms (Pseudomonas sp., Bacillus sp. and Azotobacter sp.) from the rhizospheric soil of rosemary (Rosmarinus officinalis L.) and investigate their biostimulatory (plant growth-promoting – PGP) and biocontrol potential. The bacteria isolated from the rhizosphere of rosemary included 15 bacteria of the genus Pseudomonas, 20 of the genus Bacillus, and 11 of the genus Azotobacter. Based on the morphological characteristics of colonies and cells, representative isolates of each genus were chosen (marked as Pseudomonas sp. P42, P43, P44; for Bacillus isolates B83, B84, B85, B92, B93; and for Azotobacter isolates A15 and A16) for different physiological and biochemical examination. The study included in vitro screening of the bacterial isolates for their PGP and biocontrol properties. Pseudomonas isolates showed the ability to live at low temperature (10ºC) and high pH (9), and to use different sources of carbon. All Pseudomonas isolates produced lipase, siderophore, hydrogen cyanide, and utilized organic and inorganic phosphorus, while only isolate P42 produced amylase, pectinase and cellulase. Only Bacillus isolates could grow at 45 ºC (all Bacillus isolates), pH 5 (isolates B83), and on a medium containing NaCl 5 and 7% (all isolates). Isolates denoted as B83 and B93 produced lipase, amylase, and pectinase. All isolates had the ability to solubilize phosphate, produce siderophores (except B85) and hydrogen cyanide, while only two isolates (B84 and B85) produced IAA. Azotobacter isolates had the optimal growth at 37ºC and minimal growth on a medium with pH 6 and 9. All Azotobacter isolates used all carbohydrates as a source of carbon and produced lipase, amylase, and hydrogen cyanide. The best result in suppressing the growth of pathogenic fungi Fusarium oxysporum was achieved by using isolate B92. Application of isolate B83 led to the greatest growth suppression of Sclerotinium sclerotiorum.

Biofertilizers and biostimulators have become alternative sources of plant nutrients. Biofertilizers derived from microalgae represent a new approach in plant production. The aim of the study was to examine the capacity of the microalgal cell suspension to improve germination and initial growth (root and shoot length) of white Icicle Radish (Raphanus sativus) and Kohlrabi (Brassica oleracea var. gongylodes). By applying soil microalgal biofertilizer, initial growth was improved. Compared to the control, the root length of white radish was increased by 64.24% and 41.32%, using Chlorella sp. and Dictyosphaerium sp. cell suspension, respectively. Kohlrabi root growth was stimulated by application of Chlorella sp. and Dictyosphaerium sp. suspension by 60.97% and 55.02%, respectively. A significant difference in the shoot length was recorded, as well.

A large amount of agricultural organic matter (AOM) comes into soil every day, through organic remains, and it is decomposed by bacteria, fungi and actinomycetes (Ugarković et al, 2011). The aim of this research was to select isolates of bacteria with the most organic matter degrading potential, by isolating the bacteria from five different types of soil. Isolation of bacteria was conducted from five types of soil - luvisol, cambisol, chernozem, forest land and meadow. Characterization of bacterial isolates was conducted based on morphological, physiological and biochemical features. Isolates with the most organic matter degrading potential could be used in the near future for conceptualizing microbiological preparation. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31027]

The purpose of this study is to investigate the microbial activity and the number of different groups of microorganisms in the soil under organic agricultural systems.

Gastro-intestinal nematodes (GIN) of sheep are one of major constraints in grazing production systems worldwide. Control is commonly achieved using anthelmintics, but global occurrence of anthelmintic resistance to different drugs and the emergence of multi-resistant GIN species seriously limit the efficiency of their use. Therefore, integrated parasite management is widely recommended, with nematophagous fungi as one of control tools. Duddingtonia flagrans is one of the most used species, with various effect of different isolates. In previously performed coproculture assay, we showed low efficacy of D. flagrans MUCL 9827 against infective larvae (L3) of sheep GIN. The aim of current experiment was to reevaluate its nematophagous potential, using the medium where direct interaction between the fungus and L3 could be observed. Nematophagous activity was tested on 2% water agar with addition of chloramphenicol on three series of plates seeded with 500 and 1000 chlamidospores and agar blocks with 7 days old mycelium. At Days 0 and 5, 500 L3 of sheep GIN were added to test the trapping activity. The cultures, including control plates with only L3, were incubated at 25°C for 10 days, followed by evaluation of their number and reduction percentage. Nematophagous activity of D. flagrans MUCL 9827 against L3 was clearly demonstrated. However, the overall efficacy was poor since trapping was observed only in one out of nine plates containing fungal material. Potential reasons for such poor performance of the isolate of fungal species, otherwise known as successful in trapping animal parasitic nematodes, are discussed.

The aim of this research was to investigate the microbial activity in forest soil from different sites under deciduous and coniferous trees in Serbia. One site on Stara planina was under beech trees (Fagus sp.) while another under mixture of spruce (Picea sp.) and Douglas fir (Pseudotsuga sp.). The site on Kopaonik was under mixture of beech (Fagus sp.) and spruce (Picea sp.) trees. The site on Tara was dominantly under fir (Abies sp.), beech (Fagus sp.) and spruce (Picea sp.). The total number of bacteria, the number of actinobacteria, fungi and microorganisms involved in N and C cycles were determined using standard method of agar plates. The activities of dehydrogenase and ß-glucosidase enzymes were measured by spectrophotometric methods. The microbial activity was affected by tree species and sampling time. The highest dehydrogenase activity, total number of bacteria, number of actinobacteria, aminoheterotrophs, amylolytic and cellulolytic microorganisms were determined in soil under beech trees. The highest total number of fungi and number of pectinolytic microorganisms were determined in soil under spruce and Douglas fir trees. The correlation analyses proved the existence of statistically significant interdependency among investigated parameters.

The aim of this research was to evaluate the effect of green algae Chlorella vulgaris on the initial growth of wheat, maize, bean and lettuce and the microbiological activity of rhizospheric soil. The experiment was conducted in controlled conditions. The inocula were applied as foliar fertilizer by spraying. Plant material was taken 30 days after plant emergance. Chlorella vulgaris affected positively the length (28.5% increase) and fresh mass (17.9% increase) of maize root, stem length of wheat (24.2% increase) and stem mass of lettuce (56.34% increase). Application of Chlorella vulgaris led to the increase of the total number of bacteria and the number of aminoheterotrophs in the maize rhizosphere, total bacterial number in the wheat rhizosphere, and the number of fungi in the rhizosphere of bean. The number of other investigated groups of microorganisms did not change significantly. The activity of dehydrogenase enzyme was not affected by inoculation with green algae.

Because of their huge biodiversity and metabolic capabilities, the application of microorganisms as bioremediation agents is a way to enhance pollutant degradation. The aim of this research was to investigate the potential of five strains of Pseudomonas sp. as possible bioremediation agents. Strains are from the Collection of the Microbiology Department, Faculty of Agriculture, Novi Sad. Bacterial strains were cultivated in King’s B liquid medium and incubated in shak­er at 28°C. Starter culture was obtained after 24h, CFU 108. This 24h old bacterial culture was used for the analysis of influence of five different natural naphthenic acids. Bacterial growth was determined spectrophotometrically through optical density, after 24h and 48h of growth. Our results showed that two bacterial strains (PS V1 and PS2) had better growth after 48h as they used C from the petroleum derivates. The growth of these strains was increased by 72% and 25% with deri­vates concentration of 10-5 mol/cm3 and 10-6 mol/cm3, respectively. The results of this research showed the potential of certain bacterial strains as bioremediators. [Projekat Ministarstva nauke Republike Srbije, br. TD 31027 i br. III 043002]

Growth and development of forest plants depend mostly on the soil microbial activity since no mineral or organic fertilizers are applied. Microbial processes can be activated and conditions for plants development improved with the introduction of selected microorganisms in the soil. With the aim of obtaining quality planting material in a shorter period of time, the effects of Azotobacter chroococcum and Streptomyces sp. on the early growth of black locust (Robinia pseudoacacia), Siberian elm (Ulmus pumila) and silver-leaf maple (Acer dasycarpum) were investigated in this study. Microorganisms were applied individually and in a mixture (1:1). Plant height was measured on the 90th, 120th and 180th day after planting. Plant diameter, as well as the number of actinomycetes and azotobacters was measured at the end of the vegetation period (180 days after planting). Applied microorganisms had a positive effect on the seedling height in all three plant species, with the best effect found in the black locust. Effectiveness of applied microorganisms on seedling diameter was the highest in the silver-leaf maple. The largest number of azotobacters was found in the rhizosphere of black locust. Number of microorganisms from both groups was increased in the inoculated variants. [Projekat Ministarstva nauke Republike Srbije, br. III 43002]

The dynamics of phosphorus and sulphur in soil is closely related to the dynamics of the biological cycle in which microorganisms play a central role. There is not much microbiological activity in acid soils because aerobes are scarce, rhizosphere is restricted to the shallow surface layer, and the biomass of microorganisms decreases with higher acidity. The aim of the research was to investigate the number of microorganisms, which decompose organic and inorganic phosphorus compounds and organic sulphur compounds in calcocambisol, luvisol, and pseudogley. The following parameters were determined in the soil samples: pH in H2O and in 1MKCl; the content of CaCO3 (%); humus content (%), nitrogen content (%); the content of physiologically active phosphorus and potassium (mg P2O5/100g of soil; mg K2O/100g of soil). The number of microorganisms was determined by the method of agar plates on appropriate nutrient media: the number of microorganisms solubilizing phosphates on a medium by Muramcov; the number of microorganisms that decompose organic phosphorus compounds on a medium with lecithin; and the number of microorganisms that transform organic sulphur compounds on a medium by Baar. All three types of soil are acid non-carbonate soils with a low level of available phosphorus and a more favorable amount of potassium, nitrogen, and humus. The largest number of bacteria, which transform organic phosphorus compounds, was found in calcocambisol. The largest number of phosphate solubilizing bacteria was recorded in pseudogley, whereas the largest number of phosphate solubilizing fungi was recorded in calcocambisol. The largest number of bacteria, which transform organic sulphur compounds, was recorded in pseudogley.

The effect of co-inoculation on the microbiological properties of rhizospheric soil and yield of maize was investigated in field conditions. The total number of microorganisms (TNM) was largest in variant where Plant Growth Promoting Bacteria (PGPB), Phosphorus Solubilizing Bacteria (PSB) and Arbuscular Mycorrhiza (AM) were applied. TNM was 418.10x107/g soil. The largest number of fungi was achieved in the variant with PGPM (29.65 x104/g soil). The joint use of PGPB, PSB and AM resulted in the largest number of phosphomineralizers (PM) (31.67x104/g soil). Dehydrogenase activity (DHA) increased only in the variant where all the microorganisms were introduced (924μg TPF/10 g soil). The co-inoculation led on average to the increased activity of acid phosphatase (ACP) and alkaline phosphatase (ALP). The highest yield of maize was achieved in the variant with PGPB (15.33 t/ha). Correlation analysis proved a high degree of interdependence between microbiological activity and maize yield.

Background: Various microorganisms that can have a positive or negative effect on plant development are present in the rhizospheric soil of alfalfa. The research aimed to investigate the impact of two nitrogen-fixing bacteria and two species of the phytopathogen fungus Colletotrichum on the abundance of aminoheterotrophs, nitrifying and denitrifying bacteria in the rhizosphere of three cultivars of alfalfa. Methods: The experiment was carried in vegetation pots as three factorial, where the first factor was alfalfa cultivar (Affinity+Z, K-28 and Perry), the second was the isolate of phytopathogen fungus Colletotrichum: C. trifolii (isolate Coll 4) and C. destructivum (two isolates: Coll-11 and Coll 657); and the third was the variant of bacterial inoculation (Azotobacter chroococcum and Sinorhizobium meliloti). The number of microorganisms was determined by introducing a diluted soil suspension into proper media and counted per one gram of absolutely dry soil. Result: According to the Fisher test applied inoculation microbial inoculation with nitrogen-fixing bacteria and phytopathogen fungus had different effects on the abundance of examined microorganisms in rizospheric soil of different alfalfa cultivars. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the effect of organic and conventional production on yield parameters of bean (Phaseolus vulgaris) as well as on the number of rhizospheric microorganisms. Studies were conducted at two sites on chernosem soil. Organic production was conducted on the field in the village Pivnice, while conventional production was conducted in the village Čurug, Serbia during 2014. Varieties of Balkan, Zlatko, Belko, Sremac, Slavonac, Maksa, and 20-tica were used. Before sowing, the bean seeds were inoculated by biofertilizers NS-Nitragin for beans and faba beans. NS-Nitragin contains a mixture of selected strains of symbiotic bacteria Rhizobium leguminosarum bv. phaseoli. Laboratory measurements were performed in microbiological laboratories of Faculty of Agriculture, Novi Sad and in the Institute of Field and Vegetable Crops, Novi Sad. The height and mass of the plant, the number and weight of the bean seeds per plant as well as the number of microorganisms in its rhizosphere (the total number, number of azotobacter, actinomycetes and fungi) were determined. In this research, the average values of all examined parameters of plant yields were lower in the organic production compared to conventional, except for variety Slavonac. In this case it was obtained a statistically significant increas of plant mass, number and weight of seeds per plant in organic production compared to conventional. Those results indicate that the variety Slavonac should be grown in organic production. The results showed that inoculation can have a positive effect on the number of microorganisms in the rhizosphere of the bean. The number of the investigated groups of microorganisms, apart from actinomycetes, increased in the organic production, where microbiological fertilizers were applied. In average, statistical analises showed that inoculation did not have a statistically significant impact on the number of the investigated groups of microorganisms. [ABSTRACT FROM AUTHOR]

The aim of this study was the isolation and characterization of actinomycetes (Streptomyces sp.) with PGP traits in the rhizosphere of perennial ryegrass, and monitoring the impact of their use on the parameters of the English ryegrass (Lolium perenne) yield and microbiological activity in its rhizosphere. The isolates had different growth characteristics. All three isolates produced a greater amount of indole-acetic acid (IAA) in the medium with added L-tryptophan. Isolate A3 produced siderophors and hydrogen cyanide, while isolates A1 and A2 utilized organic phosphorus. All isolates were produced cellulase, urease and gelatinase but not amylase. Isolates A1 and A3 produced lipase while A2 produced a protease. Isolate A3 was chosen for the examination of the isolate impact on plant yield. When evaluated on English Ryegrass in the field, during the first year of experiment, the isolate A3 affected positively the yield of fresh and dry mass, root and stem length. During the second year, the isolate A3 statistically significant enhanced the measured parameters over the control. In relation to Trichoderma asperellum, application of isolate A3 had a better effect on the plant yield. The number of investigated group of microorganisms and dehydrogenase activity in the inoculated variant increased in comparison with the control. [ABSTRACT FROM AUTHOR]