The effect of inoculation with Pseudomonas fluorescens and Bacillus subtilis on the yield of fresh and dry mass of English ryegrass (Lolium perenne L.) as well as on the number of rhizospheric microorganisms was studied. The microorganisms were introduced into the soil before sowing. The control plots were not inoculated. The number of microorganisms was determined after the third mowing. The yield was determined after the first, second and third mowing. In comparison with the control, after the first and second mowing, there was a statistically significant increase in the fresh and dry mass in both inoculated variants whereas after the third mowing, a statistically significant increase in the yield of fresh mass was recorded only in the variant with B. subtilis. The use of B. subtilis had a better effect on the total yield of the fresh and dry mass of English ryegrass. The number of the investigated groups of microorganisms, apart from actinomycetes, increased in the inoculated variants. Inoculation of P. fluorescens affected the increase of total number of bacteria and aminoheterotrophs whereas inoculation of B. subtilis affected the increase of the number of azotobacter and fungi.

The contemporary food production requires the preservation of soil productivity with the simultaneous maintenance of the yield level accomplished with the appropriate fertilizing. The maize and soybean production is unimaginable without fertilizers and the application of information within the filed of nitrogen fixation. The application of fertilizers has been increasing. Diazotrophs are microorganisms with the ability to fix atmospheric nitrogen and to convert it in forms available to plants. Therefore, effects of different rates of mineral nitrogen (80, 120 and 160 kg N ha-1 in maize and half of the mentioned rates in soybean), as well as, maize seed bacterisation with the associative species (Azotobacter chroococcum, Azospirillum lipoferum, Klebsiella planticola, Beijerinckia derxi) and soybean with the symbiotic species (Bradyrhizobium japonicum) and their mixture on soil biogeny and yield quality and quantity were studied. The studied parameters in maize had higher values under conditions of bacterisation and fertilization with 80 kg N ha-1, while the mixture of diazotrophs and fertilization with 40 kg N ha-1 resulted in higher values of studied parameters in soybean. It is possible to produce organic/healthy food with the maintenance of soil biogeny if diazotrophs are incorporated into the soil with lower rates of mineral nitrogen. This possibility is a basic prerequisite for sustainable agriculture

The aim of the study was to investigate ability of Pseudomonas sp. Q4b, Bacillus sp. Q5a and Azotobacter chroococcum strain 8 to enrich a population of plant growth promoting rhizobacteria (PGPR) in rhizosphere and thus enhance maize growth (Zea mays L.). Experiments were carried out under greenhouse and field conditions, on a chernozem soil. In vitro screening for PGP properties showed significant difference between indole-3-acetic acid (IAA) and siderophores production and phosphosolubilization between Pseudomonas sp. Q4b and Bacillus sp. Q5a. Pseudomonas was estimated as a better producer of hydrogen cyanide (HCN) and siderophores than Bacillus. Bacterial treatments had a significant effect on the number of investigated microbial groups in rhizosphere, and maize growth and yield. Co-inoculation had an advantage compared to single inoculation, while in case of single strains, better effects were achieved in Pseudomonas and Azotobacter treatments. Inoculation increased the number of azotobacters (103.25%), pseudomonads (82.29%) and aerobic spore-forming bacteria (52.65%) as well as height (17.15%) and dry weight (35.48%) of maize plants. The highest plant height was recorded in treatment with Pseudomonas and Bacillus. The highest dry weight and yield were recorded in the treatment with mixture of these three strains.

Antibiotic production by plant-associated microorganisms represents an environmentally compatible method of disease control in agriculture. However, a vide application of bacterial strains needs careful selection and genetic characterization. In this investigation, selected Pseudomonas strains were characterized by rep-PCR methods using ERIC and (GTG)5 primers, and partial 16S rDNA sequence analysis. None of strains produced homoserine lactones (C4, C6, C8) as quorum sensing signal molecules. Very poor production of phenazines and no significant fungal inhibition was observed for PS4 and PS6 strains. High amount of phenazines were produced by Pseudomonas sp. strain PS2, which inhibited mycelial growth of 10 phytopatogenic fungi in percent of 25 (Verticillium sp.) to 65 (Fusarium equiseti). Genetic characterization of the Pseudomonas sp. PS2 and evaluation of phenazines production, as the main trait for growth inhibition of phytopathogenic fungi, will allow its application as a biosafe PGPR for field experiments of plant disease control. [Projekat Ministarstva nauke Republike Srbije, br. III 46007: New indigenous bacterial isolates Lysobacter and Pseudomonas as an important sources of metabolites useful for biotechnology, plant growth stimulation and disease control: From isolates to inoculants

Izvod: Mikroorganizmi učestvuju u stvaranju plodnosti zemljišta, kako potencijalne tako i efektivne. Mikroorganizmi omogućavaju odvijanje procesa humifikacije i dehumifikacije i zauzimaju centralno mesto u kruženju neophodnih hranljivih makro i mikroelemenata. Zona zemljišta koja okružuje korenov sistem biljaka i pod uticajem je njegovih izlučevina može se definisati kao rizosfera. Svojim korenskim izlučevinama kukuruz može značajno da utiče na sastav i brojnost mikroorganizama u rizosferi. Biofertilizatori su mikrobiološka đubriva koja sadrže selekcionisane visoko efektivne sojeve bakterija, algi i gljiva izolovane iz zemljišta. Njihovim unošenjem u zemljište aktiviraju se odgovarajući mikrobiološki procesi koji omogućavaju bolje i ravnomernije snabdevanje biljaka azotom, fosforom i kalijumom, kao i nekim mikroelementima. Primenom biofertilizatora koji sadrže rizobakterije promotore biljnog rasta -PGPR (Plant Growth Promoting Rhizobacteria) smanjuje se upotreba skupih azotnih đubriva, omogućava se biljci lakše usvajanje fosfora i utiče na pravac i dinamiku mikrobioloških procesa.

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Inorganic phosphates, taken as NaH2PO4 or KH2PO4, stimulated the production of pectinolytic enzymes and enhanced by up to two‐fold the growth of Aspergillus niger in submerged liquid culture of apple pomace. Production of extracellular enzymes of endo‐ and exo‐ types, showed a different response to concentrations of phosphate in the medium.