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Within this paper, the potential of Streptomyces hygroscopicus in biocontrol of two isolates of Fusarium avenaceum isolated from apple fruits in the storage was tested. Production of S. hygroscopicus biocontrol agent was performed in 3 l stirred tank bioreactor at an aeration rate of 1.5 vvm and mixing speed of 150 rpm. Bioprocess was realized at 26 ±1°C for 168 hours. The activity of bioagents production was tested using in vitro diffusion method with wells. Also, residual glycerol, residual nitrogen content, and cell biomass were determined to analyze bioprocess parameters. The results showed that the highest production of bioagents was observed in 96h of cultivation when the largest zone diameters were formed against F. avenaceum KA12 and KA13 of 40.67±1.15 and 43.33±0.58 mm, respectively. The activity of the produced bioagents was confirmed in in planta research, where the difference between necrosis diameter of treated and control samples were 2.79 (for KA12) and 2.17 (for KA13) times smaller.

Within this paper, the potential of Streptomyces hygroscopicus in biocontrol of two isolates of Fusarium avenaceum isolated from apple fruits in the storage was tested. Production of S. hygroscopicus biocontrol agent was performed in 3 l stirred tank bioreactor at an aeration rate of 1.5 vvm and mixing speed of 150 rpm. Bioprocess was realized at 26 ±1°C for 168 hours. The activity of bioagents production was tested using in vitro diffusion method with wells. Also, residual glycerol, residual nitrogen content, and cell biomass were determined to analyze bioprocess parameters. The results showed that the highest production of bioagents was observed in 96h of cultivation when the largest zone diameters were formed against F. avenaceum KA12 and KA13 of 40.67±1.15 and 43.33±0.58 mm, respectively. The activity of the produced bioagents was confirmed in in planta research, where the difference between necrosis diameter of treated and control samples were 2.79 (for KA12) and 2.17 (for KA13) times smaller.

Influence of a modified media on Hexaene H-85 and Azalomycine B production by Streptomyces hygroscopicus CH-7 was investigated. The amino acid L-tryptophan, as a nitrogen source, was replaced with isatin-3-thiosemicarbazone and its complexes with some divalent metal ions. Isatin-3-thiosemicarbazone was synthesized in crude glycerol obtained as a byproduct in biodiesel production from sunflower oil. The complexes were charac-terized by elemental microanalysis and magnetic susceptibility, as well as, by Atomic absorption(AA), Fourier-transform infrared (FTIR) and Ultraviolet–visible (UV/VIS) spectro-scopic methods. The spectral studies indicated an octahedral geometry for the Mn(II), Fe(II) and Ni(II) complexes and a tetrahedral one for the Zn(II) complex. Comparing to the basal medium, isatin-3-thiosemicarbazone (ITC) and its metal complexes in the concentration of 0.5 g dm-3 showed better results in the antibiotics production. Use of medium supple-mented with the Fe(II) complex resulted in the maximum Hexaene H-85 and Azalomycine B concentrations of 306 μg cm-3 and 127 μg cm-3, respectively. Addition of ITC and its complexes changed the morphology of S. hygroscopicus CH-7 from filaments to pellets as a dominant shape in media resulting in higher antibiotic production., У раду је испитиван утицај модификованих хранљивих подлога на производњу антибиотика Hexaene H-85 и Azalomycine B помоћу Streptomyces hygroscopicus CH-7. Аминокиселина L-триптофан, као извор азота, замењена је изатин-3-тиосемикарбазоном (синтетисаним у сировом глицеролу који се добија као нуспродукт у производњи биодизела из сунцокретовог уља) и његовим комплексима са неким двоалентним металним јонима. Комплекси су карактерисани елементарном микроанализом, магнетном сусцептибилнош-ћу, атомском аспорпцијом (A), инфрацрвеним (IR) и ултравиолетним (UV/VIS) спектроскопским методама. Спектралне анализе показале су октахедралну геометрију комплекса Мn(II), Fе(II) и Ni(II) и тетраедарску за комплекс Zn(II). Изатин-3-тиосемикарбазон и његови комплекси са металима (0,5 g dm-3) утичу на повећање продукције антибиотика у поређењу са основном подлогом. Највеће концентрације антибиотика Hexaene H-85 и Azalomycine B су остварене у хранљивој подлози са Fe(II) комплексом (306 и 127 μg cm-3, редом). Комплекси ИТС и изатин 3-тиосемикарбазон утичу и на морфологију тестираног соја. Streptomyces hygroscopicus CH-7 растe у облику филамената и пелета, у подлогама у којима је остварена највећа продукција антибиотика.

Plodovi jabuke su tokom čitave godine prisutni u ishrani beba, dece i odraslih ljudi zbog čega je kvalitet i zdravstevena bezbednost ovih namirnica od izuzetnog značaja. Veliki broj fitopatogenih gljiva su prouzrokovači bolesti jabuka međutim, među značajnim prouzrokovačima bolesti jabuka u skladištima spominju se gljive iz rodova Alternaria i Fusarium. Smatra se da su zdravstveno bezbedni plodovi jabuke pre svega zdravi plodovi, bez prisustva fitopatogenih gljiva i bez ostataka fungicida. Sve veća briga oko primene sintetičkih fungicida zbog njihove toksičnosti, razvoja rezistentnosti patogena na fungicide i štetnih efekata na životnu sredinu i zdravlje ljudi, doveli su do potrebe za pronalaženjem alternative hemijskoj zaštiti, a jedno od mogućih se ogleda upravo u primeni biotehnološkim postupkom proizvedenih agenasa. Budući da su visoki troškovi biotehnološke proizvodnje osnovna prepreka za širu primenu ovih agenasa, optimizacija uslova izvođenja biosinteze predstavlja najvažniji korak ka njenom prevazilaženju. Stoga je kao cilj istraživanja u okviru ove doktorske disertacije definisana optimizacija biosinteze antagonista skladišnih patogena jabuke primenom Streptomyces hygroscopicus na nivou laboratorijskog bioreaktora u pogledu odabira izvora ugljenika i azota i količina izvora ugljenika, azota i fosfora u hranljivoj podlozi za biosintezu željenih antagonističkih agenasa, kao i parametara biosinteze sa posebnim osvrtom na intenzitet primenjene aeracije i mešanja. Analizom dobijenih rezultata zaključeno je da se podloga za kultivaciju S. hygroscopicus koja je sadržala glicerol i pored već prisutnog azota u podlozi nije sadržala dodatni izvor azota, pokazala kao najpogodnija za produkciju željenih antagonističkih agenasa efikasnih protiv izolata vrsta A. alternata i F. avenaceum. Rezultati optimizacije sastava hranljive podloge ukazuju da se primenom definisanih optimalnih vrednosti ispitivanih faktora, koje su: sadržaj glicerola od 20 g/l, sadržaj (NH4)2SO4 od 0, Apple fruits are available on the market all year round and their safety is of great importance for the consumers. Unfortunately, many phytopathogenic fungi can cause apple diseases but fungi from the genera Alternaria and Fusarium are listed among important storage pathogens of apple fruits. It is considered that health-safe apple fruits are primarily healthy fruits, without the presence of phytopathogenic fungi and without the remains of fungicides. Excessive use of pesticides in modern agriculture, including those used for control of fungal phytopathogens, has led to several problems related to pollution, environmental degradation and emergence of resistant strains. Biological control of plant pathogens by means of microorganisms is considered as an attractive alternative to chemical-based treatments, with minimal impact on the environment. The main lack of biotechnology production of the antifungal agents are the high costs, so the optimization of the biosynthesis conditions is the most important step towards its overcoming. Therefore, the aim of this research is to optimize the medium composition and process conditions (agitation and aeration rate) of the antagonists of storage apple pathogens biosinthesis by Streptomyces hygroscopicus in laboratory-scale bioreactor. Based on the obtained results, it can be concluded that the S. hygroscopicus cultivation medium containing glycerol as a carbon source, with no additional nitrogen source, proved to be the most suitable for the production of the A. alternate and F. avenaceum antagonistic agents. The results of the optimization of medium for biosynthesis of the antagonists of storage apple pathogens using S. hygroscopicus indicated the following optimal values of the examined factors: the content of glycerol of 20 g/l, (NH4)2SO4 of 0.25 g/l and K2HPO4 of 1.41 g/l. By applying the defined optimal values and using the appropriate mathematical models, the following responses are predicted: residual glycerol of 5.3418 g

Plodovi jabuke su tokom čitave godine prisutni u ishrani beba, dece i odraslih ljudi zbog čega je kvalitet i zdravstevena bezbednost ovih namirnica od izuzetnog značaja. Veliki broj fitopatogenih gljiva su prouzrokovači bolesti jabuka međutim, među značajnim prouzrokovačima bolesti jabuka u skladištima spominju se gljive iz rodova Alternaria i Fusarium. Smatra se da su zdravstveno bezbedni plodovi jabuke pre svega zdravi plodovi, bez prisustva fitopatogenih gljiva i bez ostataka fungicida. Sve veća briga oko primene sintetičkih fungicida zbog njihove toksičnosti, razvoja rezistentnosti patogena na fungicide i štetnih efekata na životnu sredinu i zdravlje ljudi, doveli su do potrebe za pronalaženjem alternative hemijskoj zaštiti, a jedno od mogućih se ogleda upravo u primeni biotehnološkim postupkom proizvedenih agenasa. Budući da su visoki troškovi biotehnološke proizvodnje osnovna prepreka za širu primenu ovih agenasa, optimizacija uslova izvođenja biosinteze predstavlja najvažniji korak ka njenom prevazilaženju. Stoga je kao cilj istraživanja u okviru ove doktorske disertacije definisana optimizacija biosinteze antagonista skladišnih patogena jabuke primenom Streptomyces hygroscopicus na nivou laboratorijskog bioreaktora u pogledu odabira izvora ugljenika i azota i količina izvora ugljenika, azota i fosfora u hranljivoj podlozi za biosintezu željenih antagonističkih agenasa, kao i parametara biosinteze sa posebnim osvrtom na intenzitet primenjene aeracije i mešanja. Analizom dobijenih rezultata zaključeno je da se podloga za kultivaciju S. hygroscopicus koja je sadržala glicerol i pored već prisutnog azota u podlozi nije sadržala dodatni izvor azota, pokazala kao najpogodnija za produkciju željenih antagonističkih agenasa efikasnih protiv izolata vrsta A. alternata i F. avenaceum. Rezultati optimizacije sastava hranljive podloge ukazuju da se primenom definisanih optimalnih vrednosti ispitivanih faktora, koje su: sadržaj glicerola od 20 g/l, sadržaj (NH4)2SO4 od 0, Apple fruits are available on the market all year round and their safety is of great importance for the consumers. Unfortunately, many phytopathogenic fungi can cause apple diseases but fungi from the genera Alternaria and Fusarium are listed among important storage pathogens of apple fruits. It is considered that health-safe apple fruits are primarily healthy fruits, without the presence of phytopathogenic fungi and without the remains of fungicides. Excessive use of pesticides in modern agriculture, including those used for control of fungal phytopathogens, has led to several problems related to pollution, environmental degradation and emergence of resistant strains. Biological control of plant pathogens by means of microorganisms is considered as an attractive alternative to chemical-based treatments, with minimal impact on the environment. The main lack of biotechnology production of the antifungal agents are the high costs, so the optimization of the biosynthesis conditions is the most important step towards its overcoming. Therefore, the aim of this research is to optimize the medium composition and process conditions (agitation and aeration rate) of the antagonists of storage apple pathogens biosinthesis by Streptomyces hygroscopicus in laboratory-scale bioreactor. Based on the obtained results, it can be concluded that the S. hygroscopicus cultivation medium containing glycerol as a carbon source, with no additional nitrogen source, proved to be the most suitable for the production of the A. alternate and F. avenaceum antagonistic agents. The results of the optimization of medium for biosynthesis of the antagonists of storage apple pathogens using S. hygroscopicus indicated the following optimal values of the examined factors: the content of glycerol of 20 g/l, (NH4)2SO4 of 0.25 g/l and K2HPO4 of 1.41 g/l. By applying the defined optimal values and using the appropriate mathematical models, the following responses are predicted: residual glycerol of 5.3418 g

The microorganisam Streptomyces hygroscopicus CH-7 produces antibiotics Hexaene, Nigericine and Elaiophyline. The yield of antibiotics can be increased by changing the fermentation conditions and the composition of the nutrient medium. Based on the previous research with this strain and the literature reviewed, the aim of this work was to study the possibility of using waste materials (whey with proteins in varying ammounts and crude glycerol from the biodiesel production) as a carbon and nitrogen source in order to increase the yeald of antibiotics produced by Streptomyces hygroscopicus CH-7. The maximum concentration of Hexaene (47,2 μg/ cm3) was achieved in the medium with whey containing 80% of protein and glycerol from sunflower oil, while the maximum concentration of Elaiophyline (24,3μg/cm3) was achived in the basal medium., Mikroorganizam Streptomyces hygroscopicus CH-7 produkuje antibiotike Heksaen, Nigericin i Elaiofilin. Promenom uslova fermentacije i sastava hranljive podloge može se povećati produkcija antibiotika. Na osnovu dosadašnjih istraživanja sa ovim sojem i literaturnog pregleda, cilj ovog rada je bio da se ispita mogućnost primene otpadnih sirovina (surutke sa različitim procentom proteina i sirovog glicerola iz proizvodnje biodizela) kao izvora ugljenika i azota, kako bi se povećala produkcija antibiotika pomoću Streptomyces hygroscopicus CH-7. Maksimalna koncentracija Heksaena (47,2 μg/cm 3) postignuta je na podlozi sa surutkom (koja sadrži 80% proteina) i glicerolom iz suncokretovog ulja, dok je maksimalna koncentracija Elaiofilina (24,3μg/cm3) ostvarena na osnovnoj podlozi.

The effect of isatin derivatives as a nitrogen source on antibiotic (hexaene H-85 and azalomycine B) production by Streptomyces hygroscopicus CH-7 was studied. Isatin-3-hydrazone, 5-chloroisatin-3-hydrazone, isatin-3-tosylhydrazone, 5-chloroisatin-3-tosylhydrazone, isatin-3-(4-hidroxy) benzoilhydrazone and 5-chloroisatin-3-(4'-hidroxy) benzoylhydrazone were synthesized in a crude glycerol, obtained during the biodiesel production from edible sunflower oil. The highest concentration of Hexaene H-85 is achieved with 5-chloroisatin-3-hydrazone (197 mu g/cm(3)) in medium, while isatin-3-hydrazone has the greatest impact on azalomycine B production (72 mu g/cm(3)).

The effect of isatin derivatives as a nitrogen source on antibiotic (hexaene H-85 and azalomycine B) production by Streptomyces hygroscopicus CH-7 was studied. Isatin-3-hydrazone, 5-chloroisatin-3-hydrazone, isatin-3-tosylhydrazone, 5-chloroisatin-3-tosylhydrazone, isatin-3-(4-hidroxy) benzoilhydrazone and 5-chloroisatin-3-(4'-hidroxy) benzoylhydrazone were synthesized in a crude glycerol, obtained during the biodiesel production from edible sunflower oil. The highest concentration of Hexaene H-85 is achieved with 5-chloroisatin-3-hydrazone (197 mu g/cm(3)) in medium, while isatin-3-hydrazone has the greatest impact on azalomycine B production (72 mu g/cm(3)).

A media consisting of isatin-Schiff bases and its inclusion complexes with beta-cyclodextrine was developed to maximize the production of antibiotics Hexaene H-85 and azalomycine B by Streptomyces hygroscopicus CH-7. The media With (-cyclodextrine inclusion complex of isatin-3-thiosemicarbazone resulted in the maximum antibiotics concentration of 493 ìg/cm3 for Hexaene H-85 and 191 ìg/cm3 for azalomycine B. The production of hexaene H-85 and azalomycine is higher when (-cyclodextrine complex is added as a nitrogen source, comparing to pure isatin-Schiff base. The maximum concentration of hexaene H-85 in medium with inclusion complex of isatin-Schiff base is 1.4-2.3 times higher than the basal medium. The maximum production of azalomycine is 2.1-3.4 times higher in media with inclusion complex of Schiff base. During the fermentation process, the nutrient media with (-cyclodextrine inclusion complexes with isatin-Schiff bases affect the strain morphology, since it is in the form of compact pellets, which are formed from short and long, branched filaments., Streptomyces hygroscopicus je soj poznat po produkciji različitih vrsta antibiotika i komercijalno važnih sekundarnih metabolita. Formiranje metabolita je rezultat mikrobioloških procesa u toku fermentacije i zavisi od nivoa biomase mikroorganizma, morfološkog profila kulture, kao i od ekoloških uslova. U cilju povećanja prinosa antibiotika, osnovna hranljiva podloga je redefinisana izmenom izvora azota, tako što su umesto sojinog brašna (10 g/dm3) dodati kompleksi Šifovih baza sa (-ciklodekstrinom (10 g/dm3). Dodatak kompleksa Šifovih baza sa bciklodekstrinom rezultirao je znatno povećanje koncentracije oba antibiotika. Maksimalna koncentracija heksaena H-85 je ostvarena na podlozi sa kompleksom izatin-3-tiosemikarbazona sa (-ciklodekstrinom i iznosila je 493 ìg/cm3, dok je za azalomicin B iznosila 191 ìg/cm3. Povećanje maksimalnih koncentracija antibiotika na podlogama sa kompleksima Schiff-ovih baza je iznosilo 1,4-2,3 puta za heksaen H-85, odnosno 2,1-3,4 puta za azalomicin B, u odnosu na osnovnu podlogu. U toku procesa fermentacije na hranljivim podlogama sa kompleksima Šifovih baza sa (-ciklodekstrinom, soj raste u obliku kompaktnih peleta, koji se formiraju od kratkih i dugih, razgranatih filamenata.

A media consisting of isatin-Schiff bases and its inclusion complexes with beta-cyclodextrine was developed to maximize the production of antibiotics Hexaene H-85 and azalomycine B by Streptomyces hygroscopicus CH-7. The media With (-cyclodextrine inclusion complex of isatin-3-thiosemicarbazone resulted in the maximum antibiotics concentration of 493 ìg/cm3 for Hexaene H-85 and 191 ìg/cm3 for azalomycine B. The production of hexaene H-85 and azalomycine is higher when (-cyclodextrine complex is added as a nitrogen source, comparing to pure isatin-Schiff base. The maximum concentration of hexaene H-85 in medium with inclusion complex of isatin-Schiff base is 1.4-2.3 times higher than the basal medium. The maximum production of azalomycine is 2.1-3.4 times higher in media with inclusion complex of Schiff base. During the fermentation process, the nutrient media with (-cyclodextrine inclusion complexes with isatin-Schiff bases affect the strain morphology, since it is in the form of compact pellets, which are formed from short and long, branched filaments., Streptomyces hygroscopicus je soj poznat po produkciji različitih vrsta antibiotika i komercijalno važnih sekundarnih metabolita. Formiranje metabolita je rezultat mikrobioloških procesa u toku fermentacije i zavisi od nivoa biomase mikroorganizma, morfološkog profila kulture, kao i od ekoloških uslova. U cilju povećanja prinosa antibiotika, osnovna hranljiva podloga je redefinisana izmenom izvora azota, tako što su umesto sojinog brašna (10 g/dm3) dodati kompleksi Šifovih baza sa (-ciklodekstrinom (10 g/dm3). Dodatak kompleksa Šifovih baza sa bciklodekstrinom rezultirao je znatno povećanje koncentracije oba antibiotika. Maksimalna koncentracija heksaena H-85 je ostvarena na podlozi sa kompleksom izatin-3-tiosemikarbazona sa (-ciklodekstrinom i iznosila je 493 ìg/cm3, dok je za azalomicin B iznosila 191 ìg/cm3. Povećanje maksimalnih koncentracija antibiotika na podlogama sa kompleksima Schiff-ovih baza je iznosilo 1,4-2,3 puta za heksaen H-85, odnosno 2,1-3,4 puta za azalomicin B, u odnosu na osnovnu podlogu. U toku procesa fermentacije na hranljivim podlogama sa kompleksima Šifovih baza sa (-ciklodekstrinom, soj raste u obliku kompaktnih peleta, koji se formiraju od kratkih i dugih, razgranatih filamenata.

Biological control of plant pathogens is considered an attractive alternative to chemical-based treatments because it has a minimal impact on the environment. In this study, in vitro antifungal efficiency of four microorganisms (Streptomyces hygroscopicus, Saccharomyces cervisae, Bacillus cereus and Leuconostoc mesenteroides) against causal agents of apple fruit rot, was investigated. Isolates of Colletotrichum acutatum, Colletotrichum gloeosporioides and Fusarium avenaceum were obtained from apple fruit samples expressing rot symptoms. Apple samples were collected during 2012 from Ultra Low Oxygen storages in Vojvodina Province, Serbia. The test microorganisms were identified according to pathogenic, morphological and ecological characteristics, and the identification of Colletotrichum isolates was confirmed by polimerase chain reaction (PCR). Antifungal effect was tested using wells method and the obtained data were processed by factorial ANOVA. Duncan's multiple range test was used to test significance of differences (p lt = 0.05) between mean values of measured radius of inhibition zones. Activity of S. cervisae, B. cereus and L. mesenteroides was not satisfactory. On the other hand, S. hygroscopicus expressed the strongest antagonism against all tested fungal isolates. The studied isolate of S. hygroscopicus showed significant antagonistic properties against storage pathogens of apple fruits identifying itself as promising biocontrol agent for commercial use.

The PI3K/Akt/mTOR signaling pathway plays a key role in diverse physiologic processes. It is also central to many aspects of the malignant process. Genetic phenomena that lead to constitutive pathway activation are common in human cancer; the most relevant are mutations affecting the catalytic subunit of PI3K and loss of function of the PTEN tumor suppressor. These factors have made this important cascade attractive as a potential target for cancer therapeutics. A host of inhibitors are now in various stages of development that target key nodes within the PI3K pathway. To date, however, the efficacy of these agents has fallen short of expectation, with at least one possible explanation being the presence of feedback loops and cross-talk that exists within and between PI3K and other signaling pathways. Accordingly, enthusiasm is again high as strategies employing therapeutic combinations are gaining pace, with encouraging results documented in both preclinical studies and emerging clinical trials. Here, we review the agents that have reached evaluation in early phase clinical studies of human subjects with cancer, and discuss the rationale for and use of novel drug combinations. © 2013 Bentham Science Publishers.

The PI3K/Akt/mTOR signaling pathway plays a key role in diverse physiologic processes. It is also central to many aspects of the malignant process. Genetic phenomena that lead to constitutive pathway activation are common in human cancer; the most relevant are mutations affecting the catalytic subunit of PI3K and loss of function of the PTEN tumor suppressor. These factors have made this important cascade attractive as a potential target for cancer therapeutics. A host of inhibitors are now in various stages of development that target key nodes within the PI3K pathway. To date, however, the efficacy of these agents has fallen short of expectation, with at least one possible explanation being the presence of feedback loops and cross-talk that exists within and between PI3K and other signaling pathways. Accordingly, enthusiasm is again high as strategies employing therapeutic combinations are gaining pace, with encouraging results documented in both preclinical studies and emerging clinical trials. Here, we review the agents that have reached evaluation in early phase clinical studies of human subjects with cancer, and discuss the rationale for and use of novel drug combinations. © 2013 Bentham Science Publishers.

A media consisting of isatin-Schiff bases (isatin-3-thiosemicarbazone, isatin-3-semicarbazone, and isatin-3-phenylhydrazone) was developed to maximize the production of antibiotics Hexaene H-85 and Azalomycine B by Streptomyces hygroscopicus. The media isatin-3-thiosemicarbazone resulted in the maximum antibiotics concentration of 372 μg cm-3 for Hexaene H-85 and 118 μg cm-3 for Azalomycine B. The impact of modified media on soil morphology also was investigated.

In culture filtrate of Streptomyces hygroscopicus a producer of polyketide antibiotics, a leucine aminopeptidase and its autogenous inhibitor were detected. The leucine aminopeptidase was purified 4573-fold with yield of 82% by combination of ion exchange and hydrophobic chromatography. The enzyme is monomeric with a molecular mass of 51 kDa determined by gel chromatography and 67 kDa determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Optimal activity was at pH 8.0 and 40°C. The pI of leucine aminopeptidase is 8.2. The enzyme is strongly inhibited by 1,10-phenantroline, amastatin and dithiothreitol. Atomic absorption spectrometry indicated 2 mols of ion zinc per mol of enzyme. The enzyme is stable at up to 70°C. Leucine aminopeptidase prefers leucine and methionine as N-terminal amino acids. Activity of leucine aminopeptidase is strongly modulated by an autogenous low-molecular weight inhibitor during fermentation, especially during periods of intensive antibiotic production.

In culture filtrate of Streptomyces hygroscopicus a producer of polyketide antibiotics, a leucine aminopeptidase and its autogenous inhibitor were detected. The leucine aminopeptidase was purified 4573-fold with yield of 82% by combination of ion exchange and hydrophobic chromatography. The enzyme is monomeric with a molecular mass of 51 kDa determined by gel chromatography and 67 kDa determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Optimal activity was at pH 8.0 and 40degreesC. The pI of leucine aminopeptidase is 8.2. The enzyme is strongly inhibited by 1,10-phenantroline, amastatin and dithiothreitol. Atomic absorption spectrometry indicated 2 mols of ion zinc per mol of enzyme. The enzyme is stable at up to 70degreesC. Leucine aminopeptidase prefers leucine and methionine as N-terminal amino acids. Activity of leucine aminopeptidase is strongly modulated by an autogenous low-molecular weight inhibitor during fermentation, especially during periods of intensive antibiotic production.

In culture filtrate of Streptomyces hygroscopicus a producer of polyketide antibiotics, a leucine aminopeptidase and its autogenous inhibitor were detected. The leucine aminopeptidase was purified 4573-fold with yield of 82% by combination of ion exchange and hydrophobic chromatography. The enzyme is monomeric with a molecular mass of 51 kDa determined by gel chromatography and 67 kDa determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Optimal activity was at pH 8.0 and 40degreesC. The pI of leucine aminopeptidase is 8.2. The enzyme is strongly inhibited by 1,10-phenantroline, amastatin and dithiothreitol. Atomic absorption spectrometry indicated 2 mols of ion zinc per mol of enzyme. The enzyme is stable at up to 70degreesC. Leucine aminopeptidase prefers leucine and methionine as N-terminal amino acids. Activity of leucine aminopeptidase is strongly modulated by an autogenous low-molecular weight inhibitor during fermentation, especially during periods of intensive antibiotic production.

In culture filtrate of Streptomyces hygroscopicus a producer of polyketide antibiotics, a leucine aminopeptidase and its autogenous inhibitor were detected. The leucine aminopeptidase was purified 4573-fold with yield of 82% by combination of ion exchange and hydrophobic chromatography. The enzyme is monomeric with a molecular mass of 51 kDa determined by gel chromatography and 67 kDa determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Optimal activity was at pH 8.0 and 40°C. The pI of leucine aminopeptidase is 8.2. The enzyme is strongly inhibited by 1,10-phenantroline, amastatin and dithiothreitol. Atomic absorption spectrometry indicated 2 mols of ion zinc per mol of enzyme. The enzyme is stable at up to 70°C. Leucine aminopeptidase prefers leucine and methionine as N-terminal amino acids. Activity of leucine aminopeptidase is strongly modulated by an autogenous low-molecular weight inhibitor during fermentation, especially during periods of intensive antibiotic production.

The effects of methyl oleate and Tween 80, hexaene H-85 production stimulators, on the fatty acid composition of the total lipids of S. hygroscopicus CH-7 were investigated. Besides oleic acid in the biomass, an increase of the branched chain fatty acid contents was observed: from 1.6 to 2.1 fold in the medium with methyl oleate and 2.5-2.9 in the medium with Tween 80 compared to the base medium. These two additives act differently on the growth of the producing strain and the uptake of valine, an essential nutrient. A decreased proteolytic activity and similar cellular fatty acid profiles indicate that the main effect of the added compounds is to facilitate the excretion of antibiotics to the outer medium, thus increasing biosynthesis., U radu je ispitivano dejstvo u podlogu dodatih metil oleata i Tween-a 80, stimulatora produkcije heksaena N-85, na sadržaj masnih kiselina u ukupnim lipidima soja S. hygroscopicus CH-7. Pored povećanja sadržaja oleinske kiseline u biomasi pri fermentaciji na podlozi sa metil oleatom sadržaj i 16:0, 17:0, 15:0 i ai 17:0, 15:0 je od 1,6 do 2,1 puta viši, dok na podlozi sa Tween-om 80 ovo povećanje iznosi 2,5-2,9 puta. Ova dva aditiva različito deluju na rast produkcionog soja kao i na brzinu usvajanja valina iz podloge. Smanjenje proteolitičke aktivnosti i sličnosti u sastavu lipida ukazuju da je verovatno najvažnije dejstvo metil oleata i Tween-a 80 stimulacija ekskrecije polienskog antibiotika u podlogu čime se povećava njegova sinteza.

The effects of methyl oleate and Tween 80, hexaene H-85 production stimulators, on the fatty acid composition of the total lipids of S. hygroscopicus CH-7 were investigated. Besides oleic acid in the biomass, an increase of the branched chain fatty acid contents was observed: from 1.6 to 2.1 fold in the medium with methyl oleate and 2.5-2.9 in the medium with Tween 80 compared to the base medium. These two additives act differently on the growth of the producing strain and the uptake of valine, an essential nutrient. A decreased proteolytic activity and similar cellular fatty acid profiles indicate that the main effect of the added compounds is to facilitate the excretion of antibiotics to the outer medium, thus increasing biosynthesis., U radu je ispitivano dejstvo u podlogu dodatih metil oleata i Tween-a 80, stimulatora produkcije heksaena N-85, na sadržaj masnih kiselina u ukupnim lipidima soja S. hygroscopicus CH-7. Pored povećanja sadržaja oleinske kiseline u biomasi pri fermentaciji na podlozi sa metil oleatom sadržaj i 16:0, 17:0, 15:0 i ai 17:0, 15:0 je od 1,6 do 2,1 puta viši, dok na podlozi sa Tween-om 80 ovo povećanje iznosi 2,5-2,9 puta. Ova dva aditiva različito deluju na rast produkcionog soja kao i na brzinu usvajanja valina iz podloge. Smanjenje proteolitičke aktivnosti i sličnosti u sastavu lipida ukazuju da je verovatno najvažnije dejstvo metil oleata i Tween-a 80 stimulacija ekskrecije polienskog antibiotika u podlogu čime se povećava njegova sinteza.

Hygromycin B is an antibiotic which possesses anthelmintic properties; it is produced simultaneously with another antibiotic - hygromycin A - by a strain of Str. hygroscopicus. Hygromycin B contains two groups of a basic character. In connection with this the separation of hygromycin B from the accompanying antibiotic can be carried out by sorption on cationites with subsequent desorption with aqueous or water-acetone solutions of ammonia or by dilute solutions of acids. To provide rapid evaluation of antibiotic concentration in solutions, the authors made an effort to develop adsorption-spectrophotometric methods of analyzing the antibiotic, working on the basis of the physicochemical properties of the antibiotic and its structural peculiarities., Edited trans. of Nauchno-Issledovatelskii Institut Antibiotikov. Konferentsii Molodykh Uchenykh Leningradskogo Instituta Antibiotikov 2-Y, Leningrad, 4-5 Jun 64. Materialy, n.p., n.d. p9-10, by Dean F.W. Koolbeck.