The antagonistic activity of the synbiotic containing Lactobacillus acidophilus and pineapple residue FOS against pathogenic bacteria

Abstract Fructooligosaccharide is used widely in many foods and pharmaceutical industries and produced by using different ways such as extracting it from plants or producing it by using plants and microorganisms enzymes. In a previous study, we extracted Fructosyltransferase (Ftase) enzyme from pineapple residue and produced FOS. In this study, we measured the antagonistic activity of two synbiotics, the first synbiotic containing Lactobacillus acidophilus and the produced FOS, the second synbiotic containing Lactobacillus acidophilus and standard FOS, against pathogenic bacteria (P. aeruginosa, E. coli, S. aureus and B cereus). The results showed that the antagonistic activity of both synbiotic types was very close, as there were no significant differences between them except in the antagonistic activity against S. aureus, there was a significant difference between the synbiotic containing the standard FOS, which was the highest in its antagonistic activity compared to the synbiotic containing the produced FOS in this study. The activity of the fructooligosaccharide (FOS) extracted from pineapple residue was evident in enhancing the activity of the probiotic bacteria (L. acidophilus), which had a major role in the production of acids and compounds that inhibited the pathogenic bacteria. The diameters of inhibition areas in the current study ranged between 19.33-28 mm, and E. coli was more susceptible to inhibition, followed by S. aureus, P. aeruginosa, and B. cereus, respectively.

Resumo O fruto-oligossacarídeo (FOS) é amplamente utilizado em muitos alimentos e indústrias farmacêuticas, e é produzido por meio de diferentes maneiras, como extraí-lo de plantas ou produzi-lo usando enzimas de plantas e microrganismos. Em um estudo anterior, extraímos a enzima frutosiltransferase (Ftase) do resíduo de abacaxi e produzimos FOS. Neste estudo, medimos a atividade antagônica de dois simbióticos: o primeiro simbiótico contendo Lactobacillus acidophilus e o FOS produzido, e o segundo simbiótico contendo Lactobacillus acidophilus e o FOS padrão, contra bactérias patogênicas (P. aeruginosa, E. coli, S. aureus e B. cereus). Os resultados mostraram que a atividade antagônica de ambos os tipos simbióticos foi muito próxima, pois não houve diferenças significativas entre eles, exceto na atividade antagônica contra S. aureus, em que houve uma diferença significativa entre o simbiótico contendo o FOS padrão, que foi o mais alto em sua atividade antagônica, em comparação com o simbiótico contendo o FOS produzido neste estudo. A atividade do fruto-oligossacarídeo (FOS) extraído do resíduo de abacaxi ficou evidente no aumento da atividade da bactéria probiótica (L. acidophilus), que teve papel importante na produção de ácidos e compostos inibidores das bactérias patogênicas. Os diâmetros das áreas de inibição no estudo atual variaram entre 19,33 e 28 mm, e E. coli foi mais suscetível à inibição, seguida por S. aureus, P. aeruginosa e B. cereus, respectivamente.

The antagonistic activity of the synbiotic containing Lactobacillus acidophilus and pineapple residue FOS against pathogenic bacteria / A atividade antagônica do simbiótico contendo Lactobacillus acidophilus e resíduo de abacaxi FOS contra bactérias patogênicas

Fructooligosaccharide is used widely in many foods and pharmaceutical industries and produced by using different ways such as extracting it from plants or producing it by using plants and microorganisms' enzymes. In a previous study, we extracted Fructosyltransferase (Ftase) enzyme from pineapple residue and produced FOS. In this study, we measured the antagonistic activity of two synbiotics, the first synbiotic containing Lactobacillus acidophilus and the produced FOS, the second synbiotic containing Lactobacillus acidophilus and standard FOS, against pathogenic bacteria (P. aeruginosa, E. coli, S. aureus and B cereus). The results showed that the antagonistic activity of both synbiotic types was very close, as there were no significant differences between them except in the antagonistic activity against S. aureus, there was a significant difference between the synbiotic containing the standard FOS, which was the highest in its antagonistic activity compared to the synbiotic containing the produced FOS in this study. The activity of the fructooligosaccharide (FOS) extracted from pineapple residue was evident in enhancing the activity of the probiotic bacteria (L. acidophilus), which had a major role in the production of acids and compounds that inhibited the pathogenic bacteria. The diameters of inhibition areas in the current study ranged between 19.33-28 mm, and E. coli was more susceptible to inhibition, followed by S. aureus, P. aeruginosa, and B. cereus, respectively.

O fruto-oligossacarídeo (FOS) é amplamente utilizado em muitos alimentos e indústrias farmacêuticas, e é produzido por meio de diferentes maneiras, como extraí-lo de plantas ou produzi-lo usando enzimas de plantas e microrganismos. Em um estudo anterior, extraímos a enzima frutosiltransferase (Ftase) do resíduo de abacaxi e produzimos FOS. Neste estudo, medimos a atividade antagônica de dois simbióticos: o primeiro simbiótico contendo Lactobacillus acidophilus e o FOS produzido, e o segundo simbiótico contendo Lactobacillus acidophilus e o FOS padrão, contra bactérias patogênicas (P. aeruginosa, E. coli, S. aureus e B. cereus). Os resultados mostraram que a atividade antagônica de ambos os tipos simbióticos foi muito próxima, pois não houve diferenças significativas entre eles, exceto na atividade antagônica contra S. aureus, em que houve uma diferença significativa entre o simbiótico contendo o FOS padrão, que foi o mais alto em sua atividade antagônica, em comparação com o simbiótico contendo o FOS produzido neste estudo. A atividade do fruto-oligossacarídeo (FOS) extraído do resíduo de abacaxi ficou evidente no aumento da atividade da bactéria probiótica (L. acidophilus), que teve papel importante na produção de ácidos e compostos inibidores das bactérias patogênicas. Os diâmetros das áreas de inibição no estudo atual variaram entre 19,33 e 28 mm, e E. coli foi mais suscetível à inibição, seguida por S. aureus, P. aeruginosa e B. cereus, respectivamente.

Screening of Endophytic Bacteria Isolated from Weed Plant to Biocontrol Stem Rot Disease on Pitaya (Hylocereus undatus)

Abstract Endophytic bacteria from weed are emerging as valuable alternatives for biochemical pesticides in sustainable agriculture. This study aims to discover the antagonistic effects of some endophytic bacteria isolated from weed (Lactuca indica) against A. alternata, a casual of stem end rot disease of pitaya. A total of 14 endophytic bacteria were isolated and four of them presented in vitro antagonistic activity against A. alternata. Of four, strain L115 significantly inhibited the pathogenic growth with a mean inhibition diameter of 12.67 ± 0.02 mm, while the other three (strain L110, L111, and L114) showed a weak inhibition. The results indicated that strain L115 could belong to the Bacillaceae family while the other three (strain L110, L111, and L114) had characteristics of the Pseudomonadaceae family. Interestingly, strain L115 showed positive results for phosphate solubilization, indole acetic acid (IAA), and biofilm production, whereas three other strains presented weak capabilities for phosphate solubilization, biofilm production and IAA production. In addition, the filtrate of strain L115 presented antifungal activity on biocontrol tests in vitro. Especially, strain L115 significantly increased seedling biomass of pitaya and tomato compared to the control. Hence, these results suggest strain L115 has the potential to be used as biocontrol agents against A. alternata. More studies should be done in the future to evaluate their efficiency in field conditions.

Insights for integrative medicinal potentials of Ethiopian Kale (Brassica carinata): Investigation of antibacterial, antioxidant potential and phytocompounds composition of its leaves / 中草药·英文版

Objective: To compare the phytochemical and antimicrobial activity of Ethiopian Kale leaves infusions, investigate the antioxidant activity and profile the major phytochemicals existing in the better solvent system. Methods: Ethiopian Kale leaves were collected from Addis Ababa, Ethiopia, and extracted using different solvents. The qualitative phytochemical analysis, antibacterial assays, and Fourier Transform Infrared (FTIR) analysis are executed for all extracts. Antioxidant assay and Gas Chromatography-Mass Spectrometry (GC–MS) analysis are carried out for the solvent system, which showed better activity in preliminary studies. Results: The qualitative phytochemical analysis exposed the presence of different classes of phytoconstituents in most of the tested extracts. The broad spectrum of antibacterial activity (7–15 mm) was noted against the tested bacterial species. The functional groups of the extracts are reported by FTIR analysis. The antioxidant ability of ethanol extract was found to be (62.92 ± 0.34)% for 2,2-diphenyl-1-picrylhydrazyl (DPPH*) assay and (71.12 ± 0.41)% for 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. More than 17 major phytocompounds in ethanol extract were profiled by GC–MS analysis. Conclusion: The ethanol extract of Ethiopian Kale leaves contain a good source of phytochemicals and it can be a significant source for various functional applications.

The effect of the lactic acid bacteria culturing conditions on their antagonistic activity to pathogens of tuberculosis

It has been found that the antagonistic activity of lactic acid bacteria depends on the composition of the nutrient medium and the temperature of culturing. It has been shown that the best antimicrobial effect to mycobacteria is achieved by the cultivation of lactic acid bacteria on the MRS nutrient media and a combined nutrient medium with the use of lactulose or glucose as a source of carbon. The optimum temperature for culturing an association of lactic acid bacteria for achieving high antagonistic activity to mycobacteria is 300C, and the duration of cultivation is 24 hours.

Trichoderma species diversity in rhizosphere soils and potential antagonism with Fusarium oxysporum / Diversidade de espécies de trichoderma em solos de rizosfera e potencial antagonismo com fusarium oxysporum

Neste estudo foram isoladas seis espécies de trichoderma isoladas de solos rizosféricos de arrozais, bananeiras, dendezeiros, seringueiras, hortaliças e pastagens. As espécies são t. harzianum, t. viride, t. koningii, t. asperellum, and t. parareesei. O estudo morfológico como pigmentação, crescimento de colônias e estudos anatômicos como aparências de conidiação, tamanho de conídios, padrão de ramificação dos conidióforos, formas de phialides, ausência ou presença de clamidósporos foram realizados para identificar as espécies de trichoderma. As espécies de trichoderma harzianum foram abundantes no solo enquanto as de t. viren foram a segunda mais frequente no solo. Todas as espécies apresentaram atividade antagônica contra o fusarium oxysporum. Enquanto t. parareesei apresentou a maior atividade antagônica de 91,10% contra f.oxysporum, relatado como melhor agente antagonista para fitopatógeno.

In this study, six species of trichoderma isolated from rhizospheric soils of rice fields, banana trees, oil palm trees, rubber trees, vegetables and pastures were isolated. The species are t. harzianum, t. viride, t. koningii, t. asperellum, and t. I will stop. Morphological studies such as pigmentation, colony growth and anatomical studies such as appearance of conidia, size of conidia, branching pattern of conidiophores, forms of phialides, absence or presence of chlamydospores were performed to identify the species of trichoderma. The species of trichoderma harzianum were abundant in the soil while those of t. viren were the second most frequent in the soil. All species showed antagonistic activity against fusarium oxysporum. While t. parareesei presented the greatest antagonistic activity of 91.10% against f.oxysporum, reported as the best antagonistic agent for phytopathogen.

Screening and Evaluation of Streptomyces Species as a Potential Biocontrol Agent against a Wood Decay Fungus, Gloeophyllum trabeum

Two-hundred and fifty-five strains of actinomycetes isolated from soil samples were screened for their antagonistic activities against four well-known wood decay fungi (WDF), including a brown rot fungus, Gloeophyllum trabeum and three white rot fungi Donkioporia expansa, Trametes versicolor, and Schizophyllum commune. A dual culture assay using culture media supplemented with heated or unheated culture filtrates of selected bacterial strains was used for the detection of their antimicrobial activity against four WDF. It was shown that Streptomyces atratus, S. tsukiyonensis, and Streptomyces sp. greatly inhibited the mycelial growth of the WDF tested compared with the control. To evaluate the biocontrol efficacy of S. atratus, S. tsukiyonensis, and Streptomyces sp., wood blocks of Pinus densiflora inoculated with three selected Streptomyces isolates were tested for weight loss, compression strength (perpendicular or parallel to the grain), bending strength, and chemical component changes. Of these three isolates used, Streptomyces sp. exhibited higher inhibitory activity against WDF, especially G. trabeum, as observed in mechanical and chemical change analyses. Scanning electron microscopy showed that cell walls of the wood block treated with Streptomyces strains were thicker and collapsed to a lesser extent than those of the non-treated control. Taken together, our findings indicate that Streptomyces sp. exhibits the potential to be used as a biocontrol agent for wood decay brown rot fungus that causes severe damage to coniferous woods.

Antagonistic Activity of α-Conotoxin TxIB Isomers on Rat and Human α6 /α3β2β3 Nicotinic Acetylcholine Receptors / 中国药学杂志

OBJECTIVE: To investigate antagonistic activities of three isomers of α-conotoxin TxIB on rat and human α6 /α3β2β3 nicotinic acetylcholine receptors (nAChRs). METHODS: Three disulfide bond isomers were synthesized using Fmoc chemistry, which were identified by ultra performance liquid chromatography (UPLC)and confirmed by MALDI-TOF mass spectrometry. Rat and human α6/α3β2β3 nAChRs were expressed in oocytes of Xenopus laevis, which were used to test the antagonistic abilities of the 3 isomers. RESULTS: The three isomers of α-conotoxin TxIB were synthesized successfully. The retention time of each isomer of α-conotoxin TxIB was different each other significantly. The observed molecular masses of three isomers were the same, which were consistent with their theoretical molecular mass. Their hydrophilicity orders were globular > ribbon > bead. Both rat and human α6/α3β2β3 nAChRs were expressed in oocytes well. Inhibition of three isomers of α-conotoxin TxIB on rat and human α6 /α3β2β3 nAChRs were evaluated respectively. Among the three isomers of TxIB, the activity of the globular isomer was the most potent one, which had almost same activity at rat and human α6/α3β2β3 nAChRs with corresponding IC50 of 28.2 and 32.0 nmol·L-1 respectively. However, the other two isomers, ribbon and bead isomers displayed little antagonistic effect on both rat and human α6/α3β2β3 nAChRs only with an IC50 of > 10 μmol·L-1. CONCLUSION: The synthesized globular isomer of α-conotoxin TxIB in this work has a high selectivity and potent antagonistic activity on rat and human α6/α3β2β3 nAChRs, which would be helpful for its new drug development.

Antimicrobial activity of endophytic fungi isolated from leaf and fruit of Eucommia ulmoides / 中草药

Objective: To isolate endophytic fungi from the leaves and fruits of Eucommia ulmoides and evaluate their antimicrobial activity.Methods: The endophytic fungi from the leaves and fruits of E. ulmoides were isolated by plate culture method, the antimicrobial activity was evaluated by standoff method, and the ability of producing bioactive compounds of E. ulmoides was investigated by HPLC. Results: A total of 52 endophytic fungi were isolated from segments of healthy the leaves and fruits E. ulmoides. Extract of two strains had a retention time identical to that of authentic chlorogenic acid. Eleven out of 52 strains exhibited antimicrobial activity to four or more fungal pathogens. The strain 29 (Alternaria SP.) showed maximum inhibition against Fusarium graminearum, and the radial growth inhibition was 82.6%. These endophytic fungi belonged to genus Alternaria, Niqrospora, and Dothideomycetes compared with the fungal sequence database at GenBank. Conclusion: Plenty of endophytic fungi from the leaves and fruits of E. ulmoides are found and 11 strains have antimicrobial activity. The antimicrobial activity of these endophytic fungi could be exploited in the biotechnological medicine and agricultural industry.

In vitro Antimicrobial Assay of Actinomycetes in Rice AgainstXanthomonas oryzae pv. oryzicola and as Potential Plant Growth Promoter

ABSTRACT The aim of this work was to invitro assay the antimicrobial activity of actinomycetes in rice against Xanthomonas oryzae pv. oryzicola and as potential plant growth promoter. A total of 92 actinomycete strains were isolated from different rice plant components and field locations. Of these, only 21.74% showed antagonistic activity against the Xoc pathogen. Molecular identification via 16s rRNA amplification revealed that 60% of the active antagonistic strains belonged to the genus Streptomyces. Isolates that demonstrated the highest antagonistic activity were also able to produce hydrolytic enzymes and plant growth-promoting hormones. Combination of preliminary screening based on in vitro antagonistic, hydrolytic enzyme and plant growth hormone activity facilitated the best selection of actinomycete candidates as evidenced by strains classification using cluster analysis (Ward's Method). Results from the preliminary screening showed that actinomycetes, especially Streptomycetes, could offer a promising source for both biocontrol and plant growth-promotion agents against BLS disease in rice.

In Vitro Antagonism and Evaluation of Chitinase Activity of Bacteria–Bacillus Circulans Against Pathogenic Fungi in Vigna Unguiculata.

Scientists of agriculture and plant pathology are on the lookout for potential biological control agents to control the plant pathogenic organisms in order to avoid soil contamination. Rhizospheric bacteria are excellent agents to control soil-borne plant pathogens. In this study an attempt has been made to evaluate the antagonistic activity of a bacterial strain Bacillus circulans against Curvularia lunata, Alternaria alternata and Cladosporium sp., which are important seed and soil borne pathogens distributed throughout the world. These infections cause grain mold and leaf spot diseases, resulting in significant economic loss to the crops. A soil bacterium Bacillus circulans isolated from the rhizospheric soil of Vigna unguiculata, showed high antagonistic activity against Curvularia lunata, Alternaria alternata and Cladosporium sp. on dual plate assay. Bacillus circulans showed a distinct inhibition zone in the dual plate assay and also produced a clear inhibition zone in chitin amended agar medium containing 0.5% colloidal chitin, indicating that it secretes chitinase.

Antagonistic activity of antibiotic producing Streptomyces sp. against fish and human pathogenic bacteria

In this study, attempts were made to isolate Streptomyces sp. from soil samples of two different regions of Bangladesh and evaluate their antagonistic activity against fish and human pathogenic bacteria. A total of 10 isolates were identified as Streptomyces sp. based on several morphological, physiological and biochemical tests. Cross streak method was used to observe the antagonistic activity of the Streptomyces sp. isolates against different fish pathogens belonging to the genus Aeromonas, Pseudomonas and Edwardsiella and human clinical isolates belonging to the genus Klebsiella, Salmonella and Streptococcus. Seven Streptomyces sp. isolates showed antagonism against both fish and human pathogenic bacteria. Four isolates viz., N24, N26, N28 and N47 showed broad spectrum of antagonistic activity (80-100%) against all genera of fish and human pathogenic bacteria. The isolate N49 exhibited highest spectrum of antagonism against all fish pathogens (90-100%) but comparatively lower degree of antagonism against human pathogens (50-60%). Rest of the two isolates (N21 and N23) showed variability in their antagonism. Results showed that broad spectrum antibiotic(s) could be developed from the isolates N24, N26, N28 and N47against several human and fish pathogens. The isolate N49 could be a potential source of antibiotic, especially for fish pathogenic bacteria.

Biocontrol of Fusarium Crown and Root Rot and Promotion of Growth of Tomato by Paenibacillus Strains Isolated from Soil

In this study, bacterial strains were isolated from soils from 30 locations of Samcheok, Gangwon province. Of the isolated strains, seven showed potential plant growth promoting and antagonistic activities. Based on cultural and morphological characterization, and 16S rRNA gene sequencing, these strains were identified as Paenibacillus species. All seven strains produced ammonia, cellulase, hydrocyanic acid, indole-3-acetic acid, protease, phosphatase, and siderophores. They also inhibited the mycelial growth of Fusarium oxysporum f. sp. radicis-lycopersici in vitro. The seven Paenibacillus strains enhanced a range of growth parameters in tomato plants under greenhouse conditions, in comparison with non-inoculated control plants. Notably, treatment of tomato plants with one identified strain, P. polymyxa SC09-21, resulted in 80.0% suppression of fusarium crown and root rot under greenhouse conditions. The plant growth promoting and antifungal activity of P. polymyxa SC09-21 identified in this study highlight its potential suitability as a bioinoculant.

Isolation of endophytes from Panax quinquefolium and screening and identification of strains with antagonistic activity / 中草药

Objective: To study the resource situation of endophytes in Panax quinquefolium of Jilin province and to select the endophytes with antagonistic effect on pathogenic fungi of P. quinquefolium. Methods: The strains with the antagonistic activity were screened by applying mixed strains method during preliminary screening and adopting the antagonism method of fermentation liquor in re-screening; Besides, the selected endogenous strains were identified via 16 S rDNA and ITS method. Results: Thirty-four endogenous strains were isolated from P. quinquefolium. After preliminary screening and re-screening, six strains with good antagonistic effect on pathogenic fungi of P. Quinquefolium were selected: B3, B11, B17, B23, B24, and F10. Among them, B3 showed an inhibitory effect on seven pathogenic fungi; F10 had a good inhibitory effect on Cylindrocarpon destructans and Alternaria panax, with an inhibitory zone diameter over 35 mm; According to the identification, B3 and F10 were Bacillus methylotrophicus and Penicillium citreonigrum respectively. Conclusion: Endophytes in P. quinquefolium are diversified and there also exist strains with high antagonistic activity, which can be a good source for biocontrol bacterium and fungus of P. quinquefolium diseases.

Antimicrobial activity of the Nisin Z producer Lactococcus lactis subsp. lactis Lc08 against Listeria monocytogenes in skim milk / Atividade antimicrobiana de Lactococcus lactis subsp. lactics Lc08 produtor de Nisina Z contra Listeria monocytogenes em leite desnatado

The presented study aimed to verify the effect of different pH values, enzyme solutions and heat treatments on the antimicrobial activity of the bacteriocinogenic strain Lactococcus lactis subsp. lactis Lc08 and to test their antimicrobial activity against Listeria monocytogenes in reconstituted skim milk at refrigeration temperatures. This strain was previously described as a nisin Z producer and capable of inhibiting L. monocytogenes growth in in vitro tests. The antimicrobial activity of the bacteriocin cell-free supernatant of Lc08 was sensitive to enzyme treatments (except papain). The pH values and heating (65ºC for 30min, 75ºC for 15s) had no apparent effect on the antimicrobial activity of the bacteriocin produced by Lc08. Only treatment at autoclave conditions result in loss of their antimicrobial activity. Lc08 presented antimicrobial activity against L. monocytogenes in the milk system after 12h at 25ºC. No effect was found at 7ºC. The results show the application viability of the Lc08 in food systems as a biopreservative against L. monocytogenes.

O presente estudo teve como objetivo verificar o efeito de diferentes valores de pH, soluções enzimáticas e tratamentos térmicos na atividade antimicrobiana da cepa bacteriocinogênica Lactococcus lactis subsp. lactis Lc08 e testar sua atividade antagonista contra Listeria monocytogenes em leite desnatado reconstituído em diferentes temperaturas de estocagem. Essa cepa já foi descrita como produtora de nisina Z e capaz de inibir o desenvolvimento de L. monocytogenes em testes in vitro. A atividade antimicrobiana do sobrenadante de Lc08 contendo a bacteriocina produzida e livre de células foi sensível ao tratamento pelas enzimas testadas (exceto papaína). A aplicação de diferentes valores de pH e o tratamento térmico (65ºC por 30 min, 75ºC por 15s) não influenciaram na atividade antimicrobiana da bacteriocina produzida por Lc08. Apenas o tratamento em autoclave resultou em perda da sua capacidade em inibir o desenvolvimento de L. monocytogenes. A cepa Lc08 apresentou atividade antagonista contra L. monocytogenes em leite após período de estocagem de 12h a 25ºC. Não foi observado efeito a 7ºC. Os resultados mostram a viabilidade de aplicação da cultura Lc08 ou de sua bacteriocina em produtos lácteos como bioconservador contra L. monocytogenes.

Bioactive potential of actinobacteria against drug resistant pathogens.

The present investigation was focused to study the antagonistic potential of actinobacterial strain TK2 isolated from Thirukurungudi Hills (Western Ghats, Tamil Nadu), against selected drug resistant bacterial pathogens. Of the 9 clinical bacterial strains, S. aureus was found to be resistant against methicillin and vancomycin while the remaining 8 gram negative pathogens were confirmed as extended spectrum beta lactamase (ESBL) producers. Strain TK2 showed good antagonistic activity against all the bacterial pathogens, except the three isolates of P. aeruginosa. Strain TK2 produced the antimicrobial activity on 4th day of incubation when growing on ISP2 agar medium whereas the same strain showed activity only on 8th day of incubation when it was grown on ISP2 broth. Of the various solvents tested for extraction, bioactive compound was extracted only in ethyl acetate. The crude extract showed 14-18 mm inhibition zone in disc diffusion method. The crude extract produced two spots in thin layer chromatography (TLC) in chloroform: methanol (30:60) solvent system. In bioautography, the second spot (Rf value 0.685) showed activity. The active compound was purified by preparative TLC, which showed maximum activity (15-20 mm inhibition) against test pathogens. Based on the results of chemical screening, the active compound was identified as sugar containing substance. Strain TK2 showed good growth on various growth media and culture conditions. Based on the studied phenotypic characteristics strain TK2 was identified as the species of the genus Streptomyces. Of the various growth parameters tested, ISP2 medium, glucose, pH 7, 1% NaCl and temperature 300C was influenced the antagonistic activity of strain TK2. Strain TK2 will be a potential for the isolation of bioactive compound(s) which will be a candidate for the development of antibiotic against drug resistant bacterial pathogens.

Application of Rhizobacteria for Plant Growth Promotion Effect and Biocontrol of Anthracnose Caused by Colletotrichum acutatum on Pepper

In vitro and greenhouse screening of seven rhizobacterial isolates, AB05, AB10, AB11, AB12, AB14, AB15 and AB17, was conducted to investigate the plant growth promoting activities and inhibition against anthracnose caused by Colletotrichum acutatum in pepper. According to identification based on 16S rDNA sequencing, the majority of the isolates are members of Bacillus and a single isolate belongs to the genus Paenibacillus. All seven bacterial isolates were capable of inhibiting C. acutatum to various degrees. The results primarily showed that antibiotic substances produced by the selected bacteria were effective and resulted in strong antifungal activity against the fungi. However, isolate AB15 was the most effective bacterial strain, with the potential to suppress more than 50% mycelial growth of C. acutatum in vitro. Moreover, antibiotics from Paenibacillus polymyxa (AB15) and volatile compounds from Bacillus subtilis (AB14) exerted efficient antagonistic activity against the pathogens in a dual culture assay. In vivo suppression activity of selected bacteria was also analyzed in a greenhouse with the reference to their prominent in vitro antagonism efficacy. Induced systemic resistance in pepper against C. acutatum was also observed under greenhouse conditions. Where, isolate AB15 was found to be the most effective bacterial strain at suppressing pepper anthracnose under greenhouse conditions. Moreover, four isolates, AB10, AB12, AB15, and AB17, were identified as the most effective growth promoting bacteria under greenhouse conditions, with AB17 inducing the greatest enhancement of pepper growth.

Optimization of cultural conditions affecting growth and improved bioactive metabolite production by a subsurface aspergillus strain TSF 146.

The aim of this study was to optimize cultural conditions for optimum growth and bioactive metabolite production by Aspergillus strain TSF 146, isolated from the subsurface soils of Brahmaputra plains, Assam, India. Agar disc diffusion assay was used to examine the antagonistic activity of the strain. The effect of different culture media, temperature, pH, incubation period, shaking, inoculum size and various carbon and nitrogen sources on the mycelial growth and bioactive metabolite production in a fixed volume of culture broth were studied. Aspergillus strain TSF 146 grew well and produced optimum bioactive metabolites in Potato dextrose broth medium at 25 °C on the 14th day of the incubation. The optimal mycelial growth, however, was obtained at pH 5.5. Sucrose (2.0 g/l) and asparagine (1.0 g/l) were the best carbon and nitrogen sources respectively for optimum growth and production of active metabolites by the isolate. Inoculum size of 2x1010 spores/ml with periodic shaking at 150 rpm optimized production of bioactive molecules. The results of the present investigation indicated that cultural conditions like carbon, nitrogen and mineral sources as well as physical factors such as temperature, pH, incubation period, inoculum size and shaking greatly affected the growth and production of bioactive metabolites by Aspergillus strain TSF 146.

Identification and biological activity of potential probiotic bacterium isolated from the stomach mucus of breast-fed lamb

The lactic acid bacterium E isolated from the stomach mucus of breast-fed lamb was identified by sequencing of 16S rDNA fragment and species-specific PCR as Lactobacillus reuteri. Its potential antimicrobial activity and ability to modulate immune system in vitro and in vivo was determined. The growth inhibition of potential pathogens decreased from Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica ser. Minnesota to Escherichia coli. The lowest inhibition activity was observed in the case of Candida albicans. The ability of L. reuteri E to modulate biological activities of human and mouse mononuclear cells was estimated in vitro and in vivo, respectively. The production of IL-1β by monocytes in vitro was significantly induced by L. reuteri E (relative activity 2.47). The ability to modulate biological activities of mononuclear cells by living L. reuteri E cells in vitro in comparison to disintegrated L. reuteri E cells in vivo differed. For example lysozyme activity in vitro was inhibited while in vivo was stimulated (relative activities 0.30 and 1.83, respectively). The peroxidase activity in vitro was stimulated while in vivo was inhibited (relative activities 1.53 and 0.17, respectively). Obtained results indicate that L. reuteri E is potential candidate to be used in probiotic preparations for animals and/or human.

Identification and biological activity of potential probiotic bacterium isolated from the stomach mucus of breast-fed lamb

The lactic acid bacterium E isolated from the stomach mucus of breast-fed lamb was identified by sequencing of 16S rDNA fragment and species-specific PCR as Lactobacillus reuteri. Its potential antimicrobial activity and ability to modulate immune system in vitro and in vivo was determined. The growth inhibition of potential pathogens decreased from Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica ser. Minnesota to Escherichia coli. The lowest inhibition activity was observed in the case of Candida albicans. The ability of L. reuteri E to modulate biological activities of human and mouse mononuclear cells was estimated in vitro and in vivo, respectively. The production of IL-1 by monocytes in vitro was significantly induced by L. reuteri E (relative activity 2.47). The ability to modulate biological activities of mononuclear cells by living L. reuteri E cells in vitro in comparison to disintegrated L. reuteri E cells in vivo differed. For example lysozyme activity in vitro was inhibited while in vivo was stimulated (relative activities 0.30 and 1.83, respectively). The peroxidase activity in vitro was stimulated while in vivo was inhibited (relative activities 1.53 and 0.17, respectively). Obtained results indicate that L. reuteri E is potential candidate to be used in probiotic preparations for animals and/or human.