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Moncef Nasri - One of the best experts on this subject based on the ideXlab platform.

  • Low-cost culture medium for the production of proteases by Bacillus Mojavensis SA and their potential use for the preparation of antioxidant protein hydrolysate from meat sausage by-products
    Annals of Microbiology, 2018
    Co-Authors: Amal Hammami, Ola Abdelhedi, Ahmed Bayoudh, Moncef Nasri
    Abstract:

    The present study aims to maximize proteases production by Bacillus Mojavensis SA strain and their use to produce bioactive protein hydrolysates from a meat by-product. The production of SA bacteria proteases was maximized using a culture medium based on wheat bran, which offer an advantage in minimizing the production cost and enhancing the enzyme activity by using agro-industrial wastes. The composition of media and cultural conditions for optimal proteases production by B. Mojavensis SA strain were investigated. A successful and significant improvement of the alkaline proteases production (four folds) by the SA strain was achieved using the medium composed of (g/l): wheat bran, 50.0; KH_2PO_4, 0.5; K_2HPO_4, 0.5; CaCl_2, 2.0; pH 6.0, where the growth conditions were monitored at 37 °C with an agitation speed of 200 rpm. Interestingly, the enzyme preparation of B. Mojavensis was applied for the preparation of protein hydrolysates from a meat by-product. Hydrolysis was carried out for 180 min at pH 12.0. The resulting hydrolysate displayed an important antioxidant activity as evaluated by the radical scavenging capacity, the reducing power, and the β-carotene bleaching inhibition. The present study showed the high proteases’ producing level by B. Mojavensis SA strain in a low-cost fermentation medium (wheat bran) and their potential use in the production of bioactive protein hydrolysate from meat by-products.

  • Proteolytic and amylolytic enzymes from a newly isolated Bacillus Mojavensis SA: Characterization and applications as laundry detergent additive and in leather processing.
    International journal of biological macromolecules, 2017
    Co-Authors: Amal Hammami, Moncef Nasri, Ola Abdelhedi, Nahed Fakhfakh, Ahmed Bayoudh
    Abstract:

    Abstract The present work aims to study the simultaneous production of highly alkaline proteases and thermostable α-amylases by a newly isolated bacterium Bacillus Mojavensis SA. The optimum pH and temperature of amylase activity were 9.0 and 55 °C, respectively, while those of the proteolytic activity were 12.0 and 60 °C, respectively. Both α-amylase and protease enzymes showed a high stability towards a wide range of pH and temperature. Furthermore, SA crude enzymes were relatively stable towards non-ionic (Tween 20, Tween 80 and Triton X-100) and anionic (SDS) surfactants, as well as oxidizing agents. Both activities were improved by the presence of polyethylene glycol 4000 and glycerol. Additionally, the crude enzymes showed excellent stability against various solid and liquid detergents. Wash performance analysis revealed that the SA crude enzymes exhibited a remarkable efficiency in the removal of a variety type of stains, such as blood, chocolate, coffee and oil. On the other side, SA proteases revealed a potential dehairing activity of animal hide without chemical assistance or fibrous proteins hydrolysis. Thus, considering their promising properties, B. Mojavensis SA crude enzymes could be used in several biotechnological bioprocesses.

  • Optimization of Protease Production by Bacillus Mojavensis A21 on Chickpea and
    2016
    Co-Authors: Faba Bean, Anissa Haddar, Moncef Nasri, Fakher Frikha, Samiha Mhamdi, Ibtissem Hamza Mnif, Alya Sellami Kamoun
    Abstract:

    Response surface methodology (RSM) was employed to optimize the medium composition and culture conditions for the production of alkaline proteases by Bacillus Mojavensis A21 on uncom-mon substrates: chickpea (CF) and faba bean (FF) flours. A significant positive influence of tem-perature, CF, FF, incubation time and inoculums size on the protease production was evaluated by Plackett Burman Design. Among these, CF was the most influential factor. The enhancement of protease to 9127 U/ml was achieved with the optimization procedure on the medium composed of (g/l): CF, 40; FF 30, NaCl 2.0; KH2PO4 1; K2HPO4 1; CaCl2, 0.1; MgSO4 0.1. The cultures were con-ducted for 72 hours with an IS of 2%, at 30˚C, an agitation speed of 150 rpm and an initial pH of 8.0. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, CF and FF, which could result in a significant reduction in the cost of medium consti-tuents. The maximum alkaline protease production was 9127 U/ml after 72 h of incubation an

  • Peptidomic analysis of bioactive peptides in zebra blenny (Salaria basilisca) muscle protein hydrolysate exhibiting antimicrobial activity obtained by fermentation with Bacillus Mojavensis A21
    Process Biochemistry, 2016
    Co-Authors: Ines Jemil, Ola Abdelhedi, Rim Nasri, Mourad Jridi, Leticia Mora, María-concepción Aristoy, Mohamed Hajji, Fidel Toldrá, Moncef Nasri
    Abstract:

    Abstract The present study investigates the antibacterial activity of zebra blenny ( Salaria basilisca ) protein hydrolysates obtained by fermentation with a proteolytic bacterium, Bacillus Mojavensis A21. The fermentative zebra blenny protein hydrolysate (FZPH), with a degree of hydrolysis (DH) of 17.35%, was fractionated by size exclusion chromatography on a Sephadex G-25 into six major fractions (F1-F6). Fraction F2, which exhibited antibacterial activity against several Gram-positive and Gram-negative bacteria, was further fractionated by reversed-phase high performance liquid chromatography (RP-HPLC). Fractions A and B from RP-HPLC exhibiting the highest antibacterial activity, were analysed using nano ESI-LC–MS/MS to identify the sequences of the peptides. A total of 28 and 41 peptides, containing from 8 to 31 amino acid residues, were identified in sub-fractions A and B, respectively. Further, identified bioactive peptides sharing sequences with previously identified peptides were reported. The results of this study suggest that FZPH is a good source of natural antimicrobial peptides and therefore, they could serve as a beneficial ingredient for nutraceuticals.

  • Acute and sub-chronic oral toxicity profiles of lipopeptides from Bacillus Mojavensis A21 and evaluation of their in vitro anticoagulant activity
    Chemico-biological interactions, 2015
    Co-Authors: Hanen Ben Ayed, Noomen Hmidet, Rim Nasri, Nawel Jemil, Ikram Ben Amor, Jalel Gargouri, Moncef Nasri
    Abstract:

    The aim of the present study was to evaluate the acute and sub-chronic toxicity of lipopeptides mixture produced by Bacillus Mojavensis A21 as well as their in vitro anticoagulant activity. A21 lipopeptides was given to mice at single dose from 75 mg to 1000 mg/kg body weight (bw). The median lethal dose (LD50) of A21 lipopeptides was about 550 mg/kg bw. Sub-chronic toxicity study for 28 days was done by daily oral administration of A21 lipopeptides at doses of 40 and 400 mg/kg bw in rats. Results showed that A21 lipopeptides did not cause any change in body weights and they did not produce any marked alterations in the hematological blood parameters including hematocrit concentration, hemoglobin level, white and red cells count. However, the platelets level decreased significantly compared to control value. Moreover, no significant differences in the serum biochemical characteristics were observed for rats treated by the lowest dose. In contrast, a little enhancement of alanine-aminotransferase (ALT) activity and decrease in total cholesterol were observed with the highest dose. A21 lipopeptides were also found to cause a prolongation of the thrombin time (TT), the prothrombin time (PT) and the activated partial thromboplastin time (APTT). Overall, A21 lipopeptides may be very promising compounds for therapeutic purposes.

Anissa Haddar - One of the best experts on this subject based on the ideXlab platform.

  • Structural elucidation and interfacial properties of a levan isolated from Bacillus Mojavensis.
    Food chemistry, 2020
    Co-Authors: Anissa Haddar, Mariem Hamed, Amir Bouallegue, Rita Bastos, Elisabete Coelho, Manuel A. Coimbra
    Abstract:

    Abstract A strain with high exopolysaccharide (EPS) production was isolated from soil and identified as Bacillus Mojavensis based on the 16S rRNA gene sequencing and biochemical properties. The EPS produced simultaneously with the growth phase reached a maximum of 22 g/L after attaining a stationary phase with sucrose used as sole carbon source. B. Mojavensis EPS (BM-EPS) was recovered, fractionated by ethanol precipitation and analysed by NMR and methylation analyses. The BM-EPS was found to be composed of (β2 → 6)-Fruf residues, characteristic of a levan, with an average molecular weight of 2.3 MDa. A homogeneous micro-porous and rough structure matrix was observed by SEM of the freeze-dried powdered sample. A concentration-dependent water-soluble nature was observed, with good water (5.3 g/g) and oil (36 g/g) holding capacities. The levan displayed good emulsification activity with excellent stability against food grade oil, thus favoring it as a promising emulsifying agent to food industries.

  • Characterization and production optimization of biosurfactants by Bacillus Mojavensis I4 with biotechnological potential for microbial enhanced oil recovery.
    Biodegradation, 2018
    Co-Authors: Imen Ghazala, Anissa Haddar, Amir Bouallegue, Semia Ellouz-chaabouni
    Abstract:

    Response surface methodology was applied to optimize the production of biosurfactants from Bacillus Mojavensis I4 using Box–Behnken design with four variables. The optimal variable combination was 3% of glucose as carbon source, 0.6% of glutamic acid as nitrogen source, temperature of 35 °C and 10 g/l of NaCl which yielded to an optimal production of 4.12 g/l. Compositional analysis and FTIR spectrum revealed that the extracted biosurfactants was a lipopeptides. The biosurfactants achieved a critical micelle concentration value of 100 mg/l. Moreover, the extracted biosurfactants were effective at recovering up to 89.2% of motor oil from sand beach and achieved a dispersion rate of 78% of the initial diameter of the oil. These findings suggested the potential use of I4 biosurfactants in the oil industry.

  • Anionic lipopeptides from Bacillus Mojavensis I4 as effective antihypertensive agents: Production, characterization, and identification.
    Engineering in life sciences, 2017
    Co-Authors: Imen Ghazala, Semia Ellouz-chaabouni, Mouna Bouassida, Fatma Krichen, José Manuel Benito, Anissa Haddar
    Abstract:

    A new isolated Bacillus Mojavensis strain I4 was found as producer of biosurfactants by different screening methods such as parafilm M test, hemolytic activity, oil displacement test, emulsification index, surface tension and lipase production assay. Enhanced biosurfactants production was obtained using glucose and glutamic acid as carbon and nitrogen sources, respectively. The optimal production of the biosurfactants was obtained by using a C/N ratio of 17, pH of 7.0 and temperature of 37°C. The surface tension was reduced to 29 mN/m and the emulsification index E24 of 62% was achieved after 72 h of culture. The purified biosurfactants showed stability with regard to surface tension reduction and emulsification in a wide range of temperatures (4-120°C), pH (4-10) and salinity (2-12% of NaCl). The thin layer chromatography showed that the produced biosurfactants were lipopeptides. The biosurfactants was characterized as a group of anionic lipopeptides with Zeta potential measurement. Chromatographic characterization using HPLC revealed that I4 lipopeptides contained numerous isoforms and surfactin was the major components. Moreover, the I4 lipopeptides showed interesting ACE-inhibitory activity. This article is protected by copyright. All rights reserved

  • Optimization of Protease Production by Bacillus Mojavensis A21 on Chickpea and
    2016
    Co-Authors: Faba Bean, Anissa Haddar, Moncef Nasri, Fakher Frikha, Samiha Mhamdi, Ibtissem Hamza Mnif, Alya Sellami Kamoun
    Abstract:

    Response surface methodology (RSM) was employed to optimize the medium composition and culture conditions for the production of alkaline proteases by Bacillus Mojavensis A21 on uncom-mon substrates: chickpea (CF) and faba bean (FF) flours. A significant positive influence of tem-perature, CF, FF, incubation time and inoculums size on the protease production was evaluated by Plackett Burman Design. Among these, CF was the most influential factor. The enhancement of protease to 9127 U/ml was achieved with the optimization procedure on the medium composed of (g/l): CF, 40; FF 30, NaCl 2.0; KH2PO4 1; K2HPO4 1; CaCl2, 0.1; MgSO4 0.1. The cultures were con-ducted for 72 hours with an IS of 2%, at 30˚C, an agitation speed of 150 rpm and an initial pH of 8.0. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, CF and FF, which could result in a significant reduction in the cost of medium consti-tuents. The maximum alkaline protease production was 9127 U/ml after 72 h of incubation an

  • Assessment of pectinase production by Bacillus Mojavensis I4 using an economical substrate and its potential application in oil sesame extraction
    Journal of food science and technology, 2015
    Co-Authors: Imen Ghazala, Semia Ellouz-chaabouni, Nadhem Sayari, Molka Ben Romdhane, Anissa Haddar
    Abstract:

    Carrot (Daucus carota) peels, local agricultural waste product, is rich in lignocellulolytic material, including pectin which can act as an inducer of pectinase production. Pectinolytic enzymes production by Bacillus Mojavensis I4 was studied in liquid state fermentation using carrot peel as a substrate. Medium composition and culture conditions for the pectinase production by I4 were optimized using two statistical methods: Taguchi design was applied to find the key ingredients and conditions for the best yield of enzyme production and The Box-Behnken design was used to optimize the value of the four significant variables: carrot peels powder, NH4Cl, inoculum size and incubation time. The optimal conditions for higher production of pectinase were carrot peels powder 6.5 %, NH4Cl 0.3 %, inoculum level 3 % and cultivation time 32 h. Under these conditions, the pectinase experimental yield (64.8 U/ml) closely matched the yield predicted by the statistical model (63.55 U/ml) with R (2) = 0.963. The best pectinase activity was observed at the temperature of 60 °C and at pH 8.0. The enzyme retained more than 90 % of its activity after 24 h at pH ranging from 6.0 to 10.0. The enzyme preserved more than 85 % of its initial activity after 60 min of pre-incubation at 30-40 °C and more than 67 % at 50 °C. The extracellular juice of I4 was applied in the process of sesame seeds oil extraction. An improvement of 3 % on the oil yield was obtained. The findings demonstrated that the B. Mojavensis I4 has a promising potential for future use in a wide range of industrial and biotechnological applications.

Noomen Hmidet - One of the best experts on this subject based on the ideXlab platform.

  • Acute and sub-chronic oral toxicity profiles of lipopeptides from Bacillus Mojavensis A21 and evaluation of their in vitro anticoagulant activity
    Chemico-biological interactions, 2015
    Co-Authors: Hanen Ben Ayed, Noomen Hmidet, Rim Nasri, Nawel Jemil, Ikram Ben Amor, Jalel Gargouri, Moncef Nasri
    Abstract:

    The aim of the present study was to evaluate the acute and sub-chronic toxicity of lipopeptides mixture produced by Bacillus Mojavensis A21 as well as their in vitro anticoagulant activity. A21 lipopeptides was given to mice at single dose from 75 mg to 1000 mg/kg body weight (bw). The median lethal dose (LD50) of A21 lipopeptides was about 550 mg/kg bw. Sub-chronic toxicity study for 28 days was done by daily oral administration of A21 lipopeptides at doses of 40 and 400 mg/kg bw in rats. Results showed that A21 lipopeptides did not cause any change in body weights and they did not produce any marked alterations in the hematological blood parameters including hematocrit concentration, hemoglobin level, white and red cells count. However, the platelets level decreased significantly compared to control value. Moreover, no significant differences in the serum biochemical characteristics were observed for rats treated by the lowest dose. In contrast, a little enhancement of alanine-aminotransferase (ALT) activity and decrease in total cholesterol were observed with the highest dose. A21 lipopeptides were also found to cause a prolongation of the thrombin time (TT), the prothrombin time (PT) and the activated partial thromboplastin time (APTT). Overall, A21 lipopeptides may be very promising compounds for therapeutic purposes.

  • Wound healing and in vitro antioxidant activities of lipopeptides mixture produced by Bacillus Mojavensis A21
    Process Biochemistry, 2015
    Co-Authors: Hanen Ben Ayed, Moncef Nasri, Hana Maalej, Sana Bardaa, Dorsaf Moalla, Mourad Jridi, Zouheir Sahnoun, Tarak Rebai, Phillipe Jacques, Noomen Hmidet
    Abstract:

    Abstract The aim of the present study was to evaluate the in vitro antioxidant activities and the in vivo wound healing performance of lipopeptides produced by Bacillus Mojavensis A21. The in vitro antioxidant activity was determined through four different assays: DPPH scavenging activity, reducing power, β-carotene bleaching by linoleic acid assay and lipid peroxidation inhibition activity. The scavenging effect of A21 lipopeptides on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical at 1 g/L was 65%. Moreover A21 lipopeptides showed good reducing power and significantly inhibited lipid peroxidation. The application of A21 lipopeptides gel on the wound site in a rat model accelerated significantly wound healing activity as compared to the control group, and a total closure was achieved after 13 days of wound induction. Further, histological study of biopsies treated with A21 lipopeptides showed fully re-epithelialized wound with a complete epidermal regeneration.

  • Identification and biochemical characteristics of lipopeptides from Bacillus Mojavensis A21
    Process Biochemistry, 2014
    Co-Authors: Hanen Ben Ayed, Gabrielle Chataigné, Marlène Chollet, Noomen Hmidet, Max Béchet, Valérie Leclère, Philippe Jacques, Moncef Nasri
    Abstract:

    Abstract This study reports the potential of a marine bacterium, Bacillus Mojavensis A21, to produce lipopeptide biosurfactants. The crude lipopeptide mixture was found to be very effective in reducing surface tension to 31 mN m −1 . PCR experiments using degenerate primers revealed the presence of nonribosomal peptide synthetases genes implied in the biosyntheses of fengycin and surfactin. Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) performed on whole cells of B. Mojavensis A21 confirmed the presence of lipopeptides identified as members of surfactin and fengycin families. Further, a detailed analysis performed by MALDI-TOF-TOF revealed the presence of pumilacidin compounds. The crude lipopeptide mixture was tested for its inhibitory activity against Gram-positive and Gram-negative bacteria, and fungal strains. It was found to display significant antimicrobial activity. Strain A21 lipopeptide mixture was insensitive to proteolytic enzymes, stable between pH 3.0 and 11.0, and resistant to high temperature. Production of lipopeptides is a characteristic of several Bacillus species, but to our knowledge this is the first report involving identification of pumilacidin, surfactin and fengycin isoforms in a B. Mojavensis strain.

  • Characterization and stability of biosurfactant produced by Bacillus Mojavensis A21 and its application in enhancing solubility of hydrocarbon
    Journal of Chemical Technology & Biotechnology, 2013
    Co-Authors: Hanen Ben Ayed, Moncef Nasri, Hana Maalej, Mourad Jridi, Noomen Hmidet
    Abstract:

    BACKGROUND The present work aimed to characterize the physicochemical properties of the biosurfactant produced by Bacillus Mojavensis A21 and to evaluate its potential use in diesel recovery. RESULTS The strain B. Mojavensis A21 was found to be a potent producer of biosurfactant. Compared with SDS and Tween 80, biosurfactant A21 showed high physicochemical properties in terms of the surface activities and high emulsification index. The biosurfactant A21 reduced surface tension to 30 mN m-1. Biosurfactant A21 was also demonstrated to be stable in a wide range of pH, temperature and salinity. Moreover, it was found that it can solubilize diesel more effectively than SDS and Tween 80. It can be considered as an alternative to chemically synthesized surfactants since it shows high solubilization efficiency towards diesel oil (62% at 0.5 g L-1) in comparison with SDS and Tween 80. CONCLUSION Biosurfactant A21, owing its high emulsification capacity and its high tolerance to acidic and alkaline pH values and salinity, shows great potential for use in bioremediation processes to enhance the solubility of hydrophobic compounds. © 2013 Society of Chemical Industry

  • Improvement of functional properties and antioxidant activities of cuttlefish (Sepia officinalis) muscle proteins hydrolyzed by Bacillus Mojavensis A21 proteases
    Food Research International, 2011
    Co-Authors: Noomen Hmidet, Ali Bougatef, Rafik Balti, Rim Nasri, Assaâd Sila, Moncef Nasri
    Abstract:

    Abstract Functional properties and antioxidant activities of cuttlefish (Sepia officinalis) muscle protein hydrolysates, with different degrees of hydrolysis (DH from 7.3% to 18.8%), obtained by treatment with Bacillus Mojavensis A21 alkaline proteases were investigated. Protein contents for all freeze-dried cuttlefish muscle protein hydrolysates (CMPHs) ranged from 80% to 86%. For the functional properties, hydrolysis by A21 proteases increased (p  The composition of amino acids of undigested and hydrolyzed proteins was determined. CMPHs have a high percentage of essential amino acids such as arginine, lysine, histidine and leucine. They have a high nutritional value and could be used as supplement to poorly balanced dietary proteins.

Charles W. Bacon - One of the best experts on this subject based on the ideXlab platform.

  • Screening of Bacillus Mojavensis biofilms and biosurfactants using laser ablation electrospray ionization mass spectroscopy.
    Journal of applied microbiology, 2018
    Co-Authors: Charles W. Bacon, Dorothy M. Hinton, Trevor R. Mitchell
    Abstract:

    AIMS Biofilms are composed of micro-organisms within a matrix of chemically complex polymer compounds and from these structures many unknown competitive factors are suggested that many considered are important consequences for biological control. This research was undertaken to study further the endophyte, Bacillus Mojavensis and its relationships to biofilm and two classes of lipopeptides considered relevant for biocontrol of plant pathogens. METHODS AND RESULTS Laser ablation electrospray ionization mass spectrometry and conventional MS/MS were used to study in situ biofilm production and the production of lipopeptides fengycin and surfactin in different strains of B. Mojavensis in plate and test tube culture on two media. All strains were capable of producing biofilm in vitro along with the accumulation of surfactin and fengycin although no concentration-dependent relationship between lipopeptide accumulation and biofilm was observed. CONCLUSION All strains studied produce biofilms in culture with the accumulated surfactin and fengycin, demonstrating that endophytic bacteria also produced biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY This study demonstrates that this endophytic species produced biofilms along with two biocontrol compounds of which one, surfactin, considered by others as a quorum sensor, highlighting its ecological role as a signalling mechanism in planta.

  • Bacillus Mojavensis RRC101 Lipopeptides Provoke Physiological and Metabolic Changes During Antagonism Against Fusarium verticillioides
    Molecular plant-microbe interactions : MPMI, 2016
    Co-Authors: A. A. Blacutt, Trevor R. Mitchell, Charles W. Bacon, Scott E. Gold
    Abstract:

    The mycotoxigenic pathogen Fusarium verticillioides threatens the quality and utility of maize across industrial and agricultural purposes. Chemical control is complicated by the intimate endophytic lifestyle of the pathogen with its host. Bacillus Mojavensis RRC101, a maize-endophytic bacterium, has been observed to reduce F. verticillioides disease severity and fumonisin accumulation when coinoculated to maize. Genome sequencing and annotation identified a number of biocontrol-relevant pathways in RRC101. Biochemical assays confirmed the presence and activity of surfactin- and fengycin-type lipopeptides, with fengycins responsible for antifungal activity against F. verticillioides. This antagonism manifests as inhibition of filamentous growth, with microscopy revealing hyphal distortions, vacuolization, and lysis. F. verticillioides secondary metabolism also responds to antagonism, with lipopeptide challenge inducing greater fumonisin production and, in the case of fengycins, eliciting pigment accumulat...

  • Whole-Genome Shotgun Sequence of Bacillus Mojavensis Strain RRC101, an Endophytic Bacterium Antagonistic to the Mycotoxigenic Endophytic Fungus Fusarium verticillioides.
    Genome Announcements, 2014
    Co-Authors: Scott E. Gold, A. A. Blacutt, Richard J. Meinersmann, Charles W. Bacon
    Abstract:

    ABSTRACT Here, we report the whole-genome shotgun sequence of Bacillus Mojavensis strain RRC101, isolated from a maize kernel. This strain is antagonistic to the mycotoxigenic plant pathogen Fusarium verticillioides and grows within maize tissue, suggesting potential as an endophytic biocontrol agent.

  • Characterization of endophytic strains of Bacillus Mojavensis and their production of surfactin isomers
    Biological Control, 2012
    Co-Authors: Charles W. Bacon, Trevor R. Mitchell, Dorothy M. Hinton, Maurice E. Snook, Babatunde Olubajo
    Abstract:

    Abstract Bacillus subtilis consists of a large collection of strains from which several cryptic species have been delineated, and most of these along with strains within the species are important biocontrol agents. Bacillus Mojavensis , a species recently distinguished from this broad B. subtilis group of bacteria, was determined to be endophytic and to have biocontrol potential due to its inhibition of the maize mycotoxic fungus Fusarium verticillioides . Recently, we reported that a patented strain B. Mojavensis produced the biosurfactant Leu 7 -surfactin that was inhibitory to fungi. In this study, the first objective was to validate the identity of strains, and analyze genotypically a collection of B. Mojavensis strains, which involved analysis of repetitive-PCR amplified Bacillus DNA sequences with a PCR genotyping bar system. In an effort to understand further surfactin production, a second objective was to screen this collection of B. Mojavensis strains for surfactin analogs. The results indicated that all strains are valid B. Mojavensis , and that there was genotypic diversity among strains from the great deserts. Further, the study established that most strains can produce a mixture of surfactins that was comprised of acyl chain lengths ranging from C-11 to C-17. These experiments indentified high producers of C-15 surfactin, the most biologically active isoform. However, the in vitro inhibition observed did not necessarily relate to total surfactin concentrations, suggesting a complex mechanism for inhibition and/or the presence of other unknown factors.

  • Bacillus Mojavensis : Its Endophytic Nature, the Surfactins, and Their Role in the Plant Response to Infection by Fusarium verticillioides
    Bacteria in Agrobiology: Plant Growth Responses, 2011
    Co-Authors: Charles W. Bacon, Dorothy M. Hinton
    Abstract:

    Bacterial endophytes are fundamentally important as natural components of most plants, wild and cultivated with strong ecological merits. These ancient associations are recently at the forefront of biological control strategies designed to circumvent the problems associated with pesticide uses, particularly on specific food crops. Bacterial endophytes form compatible associations that persist during the growing seasons, where several enhanced benefits are associated, suggesting that such associations are mutualistic. Several genera of bacteria are known as root associations, and only recently are species being identified as plant endophytes, occupying the entire plant axis in most cases. Bacillus Mojavensis was discovered in maize kernels and later determined to be an endophyte with biocontrol potential due to its inhibition of the maize mycotoxic and pathogenic fungus Fusarium verticillioides, itself an endophyte. It was subsequently shown that this strain and others were inhibitory to most fungi, especially plant pathogenic species. Further, maize plants infected with B. Mojavensis showed a marked improvement in foliage and root growth and development, disease protection, and mycotoxin reduction. Components of B. Mojavensis-infected maize are reviewed relative to biocontrol of F. verticillioides and other endophytic fungi. The patented and other strains of this bacterium were recently reported as producers of the lipopeptide biosurfactant Leu7-surfactin. The chemistry, fermentation of the surfactins, and their uses, along with the essential features of surfactins required for fungal inhibition, are discussed. We also review the host–parasite relations of this bacterial endophyte, and its biochemical utility in an effort to bring attention to the potential qualities of B. Mojavensis, and other bacterial endophytes for enhancers of plant growth and protectors of diseases.

Rani Gupta - One of the best experts on this subject based on the ideXlab platform.

  • Statistical media optimization and alkaline protease production from Bacillus Mojavensis in a bioreactor
    Process Biochemistry, 2003
    Co-Authors: Qasim Khalil Beg, Vikram Sahai, Rani Gupta
    Abstract:

    Alkaline protease production in Bacillus Mojavensis was improved up to 4.2-fold in a 14 l bioreactor during validation of a predicted statistical model. The final enzyme yield in the bioreactor was 2389 U ml−1 obtained within 10–12 h compared to 558 U ml−1 after 24 h in shake flask cultures. Analysis of variance (ANOVA) of face-centered central composite design showed a high coefficient of determination (R2) value of 0.9473, thus ensuring a satisfactory adjustment of the quadratic model with the experimental data. The coordinates of three factors (casamino acids, inoculum age and agitation) were positive, whereas negative coordinates were obtained for other two factors (glucose and incubation time). Protease production was subjected to catabolite repression by glucose (>2 mg ml−1). The response surface curves predicted increased levels of casamino acids (12 mg ml−1) and midlevel of glucose (2 mg ml−1) as best C/N combination for optimal enzyme production (1133 U ml−1) within 18 h at high agitation rates (>250 rpm) and low inoculum density (A550 nm≅0.250). Protease production was drastically reduced at low agitation rates. The present study provides useful information about the regulation of protease synthesis through manipulation of various physicochemical factors.

  • Purification and characterization of an oxidation-stable, thiol-dependent serine alkaline protease from Bacillus Mojavensis
    Enzyme and Microbial Technology, 2003
    Co-Authors: Qasim Khalil Beg, Rani Gupta
    Abstract:

    Abstract An extracellular, thiol-dependent and oxidation-stable alkaline serine protease (molecular mass 30 kDa on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE)) from Bacillus Mojavensis was purified to homogeneity with 17-fold purification as unbound fractions using a single step anion exchange chromatography on fast flow Q-sepharose column pre-equilibrated with buffer of pH 10.5. The N-terminal sequence of first 15 amino acids of purified protease showed 91% similarity with other subtilisins and alkaline proteases. The enzyme exhibited pH and temperature optima of 10.5 and 60 °C, respectively, and was stable between a wide pH range of 7.0 and 11.5 for 48 h. The half-lives of protease at 60, 65, and 70 °C were 150, 15 and 7 min, respectively. Various stabilizers and additives stabilized protease for more than 4 h at 60 °C, and 45 min at 65 °C. Specific protease inhibitors, such as phenylmethyl sulfonyl fluoride (PMSF), bestatin, chymostatin, iodoacetic acid, and N -bromosuccinimide completely inhibited the enzyme activity, whereas, the enzyme activity was increased up to more than two-fold in presence of 2-mercaptoethanol, glutathione, and dithiothreitol, suggesting it to be a thiol-dependent serine protease. Among metal ions, Cu 2+ and Mn 2+ ions increased enzyme activity up to 36%. The enzyme was also stable towards several commercially available laboratory bleaches (H 2 O 2 , sodium perborate), surfactants (tweens, Triton X-100, sodium choleate), and other commercial detergents used in laundries. The protease hydrolyzed several native proteinacious substrates, such as gelatin, elastin, albumin, haemoglobin, and skim milk, thus making it suitable for its use as an effective detergent additive. Wash performance analysis of enzyme revealed that it could effectively remove a variety of stains, such as blood, beetle and grass most effectively at 60 °C.

  • De-repression and subsequent induction of protease synthesis by Bacillus Mojavensis under fed-batch operations
    Process Biochemistry, 2002
    Co-Authors: Rajendra Kumar Saxena, Rani Gupta
    Abstract:

    Abstract Bacillus Mojavensis produced 440 U ml −1 of an alkaline protease during batch-fermentation at 50 °C in a minimal medium containing casamino acids. Enzyme production was inducible in the presence of organic nitrogen, was maximal in casein and casamino acids and was repressed by glucose and ammonium ions. A fed-batch strategy was adopted to enhance protease synthesis by using intermittent de-repression and induction during the growth of the organism. In the first biomass production phase, the growth of the bacterium was achieved in non-inducible conditions for 6 h in the presence of glucose and ammonium ions. Feeding of casamino acids at this stage resulted in a 2.8-fold (1219 U ml −1 ) increase in protease yield after 36 h compared to the protease yield in batch culture. This protease production was enhanced further to fourfold (1770 U ml −1 ) in the second fed-batch operation on the onset of the second stationary phase by a glucose feed (5 mg ml −1 ) at 33 h followed by a casamino acids feed (5 mg ml −1 ) at 36 h. The overall fermentation process was highly sensitive to agitation and protease production was drastically inhibited at low agitation conditions and only negligible amounts of protease was produced in static culture.

  • Kinetic constants determination for an alkaline protease from Bacillus Mojavensis using response surface methodology.
    Biotechnology and bioengineering, 2002
    Co-Authors: Qasim Khalil Beg, R.k. Saxena, Rani Gupta
    Abstract:

    The kinetic constants for an alkaline protease from Bacillus Mojavensis were determined using a central composite circumscribed design (CCCD) where concentration of substrate (casein) and the assay temperature were varied around their center point. The K(m),V(max), K(cat), activation energy (E(a)) and temperature coefficient (q(10)) were determined and the values of these kinetic constants obtained were found comparable to that obtained with conventional methods. The Michaelis-Menten constant (K(m)) for casein decreased with corresponding increase in V(max), as reaction temperature was raised from 45-60 degrees C. The protease exhibited K(m) of 0.0357 mg/ml, 0.0270 mg/ml, 0.0259 mg/ml, and 0.0250 mg/ml at 45, 50, 55, and 60 degrees C, respectively, whereas V(max) values at these temperatures were 74.07, 99.01, 116.28, and 120.48 microg/ml/min, respectively, as determined by response surface methodology. The Arrhenius plot suggested that the enzyme undergoes thermal activation above 45 degrees C until 60-65 degrees C followed by thermal inactivation. Likewise, the energy of activation (E(a)) was more between 45-55 degrees C (9747 cal/mol) compared to E(a) between 50-60 degrees C (4162 cal/mol).