Bacteria Azotobacter Chroococcum Research Articles

Increased Nitrogenase Activity in Solar‐Driven Biohybrids Containing Non‐photosynthetic Bacteria and Conducting Polymers

AbstractA conductive polymer‐based photosynthetic biohybrid is constructed to enhance biological nitrogen fixation by increasing nitrogenase activity in the non‐photosynthetic bacterium Azotobacter Chroococcum (A. Chroococcum). The light‐harvesting cationic poly(fluorene‐alt‐phenylene) (PFP) electrostatically binds to the surface of the bacteria and possesses satisfactory conductivity to facilitate electron transfer to the bacterium, promoting the nitrogen fixation pathway through redox proteins on the surface of the bacteria when under illumination. Therefore, the nitrogenase activity, hydrogen, NH4+‐N and L‐amino acids production are increased by 260 %, 37 %, 44 %, and 47 %, respectively. The expression levels of nifD and nifK encoding molybdenum‐iron (MoFe) protein and relevant nitrogen‐fixing proteins are up‐regulated. These photoactive conductive polymer‐bacteria biohybrids provide a new method for improving the biological nitrogen fixation capability of non‐photosynthetic nitrogen‐fixing bacteria.

Increased Nitrogenase Activity in Solar-Driven Biohybrids Containing Non-photosynthetic Bacteria and Conducting Polymers.

A conductive polymer-based photosynthetic biohybrid is constructed to enhance biological nitrogen fixation by increasing nitrogenase activity in the non-photosynthetic bacterium Azotobacter Chroococcum (A. Chroococcum). The light-harvesting cationic poly(fluorene-alt-phenylene) (PFP) electrostatically binds to the surface of the bacteria and possesses satisfactory conductivity to facilitate electron transfer to the bacterium, promoting the nitrogen fixation pathway through redox proteins on the surface of the bacteria when under illumination. Therefore, the nitrogenase activity, hydrogen, NH4 + -N and L-amino acids production are increased by 260 %, 37 %, 44 %, and 47 %, respectively. The expression levels of nifD and nifK encoding molybdenum-iron (MoFe) protein and relevant nitrogen-fixing proteins are up-regulated. These photoactive conductive polymer-bacteria biohybrids provide a new method for improving the biological nitrogen fixation capability of non-photosynthetic nitrogen-fixing bacteria.

IMPROVEMENT OF ORGANIC TECHNOLOGY OF TABLE CARROT GROWING ON THE RIDGE

The article considers the biological significance of table carrots in human life and the country's economy. It is concluded that the value of table carrots, first of all, is explained by the presence in its composition of a large set of useful substances for the vital functions of the human body. The special value of carrots is that its varieties have an orange color of roots containing carotene (provitamin A), which in humans and animals is converted into vitamin A. Named the most promising hybrids of carrots, lists the basic climatic requirements for growing high yields of this vegetable. The most important conditions of organic carrot cultivation are briefly described. The stages of the technological scheme of carrot cultivation by organic technology are described and the influence of organic cultivation technology on the biometrics of the carrot plant in 2018–2020 is estimated. Analyzing the results of a field experiment on organic cultivation of table carrots, we can say that as a result of organic cultivation and simultaneous application of organo-mineral fertilizer HelpRost vegetables or HelpRost Boron plant height of Abaco F1 hydride was the highest and amounted to 76 cm, which exceeded the height of control plants almost 1.5 times. The variants in which the Abaco F1 and CB 7381 MS F1 hybrids were grown were characterized by the corresponding length. In these variants, the length of the root was the longest and was 16 and 17 cm, respectively, which exceeded the control variant by 4 and 5 cm, respectively. It was found that the bacteria Azotobacter chroococcum and Bacillus subtilis of the biological product of BTU-Center and chelated microelements, improve the biometrics of the plant and root crop (most positively for the root of Abaco F1 hydride where their value can be 5.1 cm. The yield of table carrot hybrids using organic technology, t / ha for 2018–2020 was studied and it is said that the highest yield can be obtained by growing Abaco F1 hybrid, where its value reaches 68 t / ha . During the cultivation of hybrids Bolivar F1 and SV 7381 MS F1 the yield is lower, is only 61.0-62.5 t / ha and exceeded the yield of Olympi F1 hybrid by 9 and 6%, respectively.

Influence of biofertilizers application to improve growth and yield of celery in Andisols

Increasing crop production in sustainable agriculture needs environmentally friendly inputs. Biofertilizers are fertilizers that contain beneficial soil microbes capable of facilitating the availability of soil nutrients. The experiment was carried out to examine the effect of application of biofertilizers on the growth and yield of celery on Andisols of West Java, Indonesia. The field experiment using a Randomized Block Design (RBD) consisted of five treatments with six replications. The treatments consisted of four types of biofertilizer, and one control treatment, , included: inorganic compound NPK fertilizer (control), microbial coated urea I, microbial coated urea II, mixed biofertilizer, mixed biofertilizer phosphate enriched nitrogen microbes. The microbial coated urea consists of Azotobacter and Bacillus bacteria composition, this formula is made by coating prilled urea with concentration liquid biofertilizer of microbe coated urea I 10%, and microbe coated urea II 5%. The consortium biofertilizer is formulated in liquid inoculant consists of N-fixing bacteria Azotobacter chroococcum, A. vinelandii, Azospirillum sp. and Acinetobacter sp., P-solubilizing microbes Burkholderia cepacea and Penicillium sp.. The mixed biofertilizer phosphate consists of Burkholderia cepace, Pseudomonas mallei, Aspergillus niger and Penicillium sp. The results showed that application of mixed biofertilizers consists of N-fixing bacteria Azotobacter chroococcum, A. vinelandii, Azospirillum sp. and Acinetobacter sp., P-solubilizing microbes Burkholderia cepacea and Penicillium sp. had better in increasing for growth and yield of celery.

Stimulating effects of reduced graphene oxide on the growth and nitrogen fixation activity of nitrogen-fixing bacterium Azotobacter chroococcum

Graphene has found important applications in various areas and hundred tons of graphene materials are annually produced. It is crucial to investigate both the negative and positive environmental effects of graphene materials to ensure the safe applications and develop environmental applications. In this study, we reported the stimulating effects of reduced graphene oxide (RGO) to nitrogen-fixing bacterium Azotobacter chroococcum. RGO stimulated the cell growth of A. chroococcum at 0.010–0.500 mg/mL according to the growth curves and the colony-forming unit (CFU) increases. RGO wrapped over the A. chroococcum cells without inducing ultrastructural changes. RGO decreased the leakage of cell membrane, but slight oxidative stress was observed in A. chroococcum. RGO promoted the nitrogen fixation activity of A. chroococcum at 0.5 mg/mL according to both isotope dilution method and acetylene reduction activity measurements. Consequently, the increases of soil nitrogen contents were evidenced, in particular about 30% increase of organic nitrogen occurred at 0.5 mg/mL of RGO. In addition, RGO might possibly benefit the plant growth through enhancing the indoleacetic acid production of A. chroococcum. These results highlighted the positive environmental effects of graphene materials to nitrogen-fixing bacteria in nitrogen cycle.

Биогеохимическая характеристика корнеобитаемого слоя травянистых растений на рекультивированных участках техногенных отходов

The introduction of the work substantiates the relevance of studying the biogeochemistry of the root layer of herbaceous plants growing on man-made waste from coal mining and iron ore enrichment after 40 years of reclamation. The main part of the report is devoted to the results of determining the gross content of heavy metals and metalloids, Sorg., residual toxicity, occurrence and growth characteristics of the bacterium Azotobacter chroococcum in embryos and background soil under similar plants. It is shown that during the long-term development of embryosems on waste of different origin, a high pool of heavy metals and metals is preserved in them, and Sorghum accumulates. In the area of coal mining around the roots of the clover, the maximum concentrations of Pb are detected, while cereals - Br. On the forested tails of the iron ore agglomeration, the trend is different: Ca, Ni, Cu, Mn, Zn are concentrated around the roots of cereals, and As is near the roots of the clover. However, the residual toxicity is manifested only on the tailings of the iron ore agglomeration. It has been established that the occurrence of azotobacter in the root layer of different plants is ubiquitous, but in the embryos of the forested tailings pond, the bacterial populations are heterogeneous, they contain donkey strains showing luminescence, rhizoid growth type and antagonism. Around the roots of the clover, conditions were formed that were less favorable for reproduction than under cereals. The data obtained expand knowledge about the role of phytobiomes in the migration of chemical elements at man-made facilities, can be taken into account when developing toxicity neutralization and in predicting the effectiveness of biological reclamation.

Microbiological integration for qualitative improvement of vermicompost

Purpose This study was carried out to assess the effect of integrating microbiological fortification with vermicomposting process on biofertilizing quality of vermicompost as well as improvement of the availability of nitrogen and phosphorus in the product. Method A mixture of cow dung and vegetable market waste (1:1) was used for vermicomposting with Eisenia foetida as the decomposer earthworm @ 10 no.of worm kg-1 substrate. Nitrogen fixing and phosphate solubilizing bacteria (NFB and PSB)Azotobacter chroococcum and Pseudomonas fluorescens were integrated with this composting process at varying doses viz. 0,5 and 10 g kg-1 substrate under different combinations. Changes in the population of these two bio-fertilizing microorganisms and the availability of relevant nutrients in the substrates were monitored periodically to assess the behaviors of these microorganisms and their effects on the produced vermicompost. Results All the inoculations resulted in substantial increments in population of both NFB and PSB over the control. However, the increments were more prominent for NFB than the PSB. Significant increments in the amount of mineralized nitrogen and solubilized phosphate over the control were observed in almost all the treatment combinations. Conclusion Integration of nitrogen fixing and phosphate solubilizing bacteria with vermicomposting process resulted in substantial enrichment of the product. This benefit was observed not only in terms of increased availability of the two major plant nutrients of concern viz. N and P, but also in significant improvement in the population of the inoculated microorganisms turning the product into a potential source of bio-fertilizers.

Toxicity and environmental impact of multi-walled carbon nanotubes to nitrogen-fixing bacterium Azotobacter chroococcum

With the large-scale production and wide applications of carbon nanotubes (CNTs), they are inevitably entering the environment and bringing unknown threats to environmental organisms. Nitrogen-fixing bacteria dominate 80% of the nitrogen fixation in nitrogen cycle. Herein, we investigated the toxicity and environmental impact of multi-walled CNTs (MWCNTs) to nitrogen-fixing bacterium Azotobacter chroococcum. MWCNTs slightly inhibited the growth of A. chroococcum and induced small increase of death rate at high concentrations. MWCNTs did not penetrate the cell walls of A. chroococcum and no cytoplasm loss was observed. MWCNTs were only observed surrounding the A. chroococcum cells. According to oxidative stress assays, MWCNTs induced meaningful oxidative damage at 0.5 mg/mL after 6 d exposure, but the oxidative damage diminished at 14 d. MWCNTs did not affect the nitrogen fixation activity of A. chroococcum and the soil nitrogen contents. Our findings provided the fundamental data for the environmental safety of CNTs to nitrogen-fixing bacteria.

Проблемы и перспективы вовлечения отходов обогащения полиметаллических и железных руд в биологическую консервацию

Ore enrichment waste is a fine material that poses a serious environmental problem. However, the high residual content of rare and precious metals, as well as valuable metalloids, determines the preservation of technogenic formations as secondary mineral raw materials. This dictates the search for environmentally safe conservation of waste before its subsequent development. This report focuses on reducing the phytotoxicity of waste and the use of bioagumentation - the introduction of exogenous plant matter and azotobacteria into the root layer, which contributes to the optimization of the mineral nutrition of phytoconservants. The article examines the physical and chemical parameters of polymetallic ore dressing waste before and after chemical reclamation, provides information on changes in the composition of watersoluble forms of metal elements (Fe, Mn, Al, Cu, Zn, Cd, Co, Ni), a decrease in the anionic content of the sulfate ion, and the appearance of hydrocarbonates. It is experimentally established that after chemical reclamation of spent slags, their viability for seedlings of oats and white mustard increases. After reclamation, there is an increase in their morphometric indicators. Mustard reacts especially positively to the decrease in acidity and mobility of metals. The dry weight of its seedlings increases-by almost 30% compared to the control. When mustard seeds are inoculated with a suspension of a live culture of the bacterium Azotobacter chroococcum, its roots elongate and their weight increases. It is shown that the growth of mustard roots is also activated on iron ore processing waste that is subject to forest reclamation. But in such conditions, vital azotobacteria exhibit a glow, especially intense in small sand fractions. Chemolumi-nescent reactions ensure the survival of azotobacteria in the development of free radical reactions caused by the residual content of magnetic iron and lignin in the habitat. The revealed features of the growth of oat and mustard seedlings, as well as azotobacteria on ore dressing waste, should be taken into account when developing technologies to increase the biogenicity of the waste surface in vivo, to argue for the use of bioagumentation in creating technologies for environmentally safe waste conservation without involving the fertile soil layer - an irreplaceable natural resource.

FEATURES OF APPLICATION OF BIOPREPARATIONS FOR CULTIVATION OF OYSTER MUSHROOMS ON STRAW SUBSTRATE

The world’s population consumes a significant amount of mushrooms each year. Beginners in mushroom growing are considered to be the Chinese, who at the beginning of our era learned to grow different species of basidiomycetes. Today, Ukraine has a significant potential for the development of mushroom growing: there are the necessary raw materials for substrates and still unoccupied premises. Research institutions preserve a unique collection of high-yielding strains, and specialized laboratories produce high-quality seed mycelium. The article is devoted to the study of the influence of biologicals on the productivity of oyster mushrooms of the common strain K-12 during intensive cultivation on a straw substrate. Based on research, it is established that the use of biologicals as an adjunct to the substrate affects the growth processes of the fungus. Biometric indicators of fruit body weight with the use of azotophyte or phytocyde exceeded the indicators of fruit body weight grown on the substrate, where the biological product was not used by 2,0 g, and the diameter of the cap was inferior to 2,0 and 6,0 mm, respectively. Fungi obtained on the substrate without the use of the biological product were characterized by a shorter leg length compared to the variant using azotophyte by 3,0 mm, and exceeded the test value by 4 mm using phytocyde. From the use of azotophyte or phytocide, the diameter of the stem of the fruiting body decreases to 12,0-15,0 mm. Carrying out of timely agrotechnical actions promotes reception of a qualitative harvest of fruit bodies of an oyster mushroom. Before harvesting, the fruiting bodies were characterized by a typical shape and inherent color of the cap and were in technical maturity. The cap of the fruit body did not crack, was not damaged by pests, and its humidity was 65,0-68,0 %. The activity of the bacteria Azotobacter chroococcum and Bacillus subtilis has an effect on the productivity of strain K-12, they stimulate the formation of more primordia. With the use of Azotophyte or Phytocide, the yield increases by 22,0 and 18,0 %. The total yield of oyster mushroom consists of two waves of fruiting. The yield of the first wave of fruiting is 2,3 times higher than the yield of the second wave of fruiting. The use of Azotophyte helps to increase the yield of the first wave of fruiting fungus by 2,2 kg / 100 kg of substrate, and phytocide – by 1,8 kg / 100 kg of substrate. The use of Azotophyte or Phytocyde as an additive to the substrate is economically advantageous: the net profit increases by 32 and 24 %, and the level of profitability - by 1,2-1,1 times, respectively.

LEAF-FEEDING PROCESSING OF PLANTS OF THE TOMATILLO BIOPROOFICIANS UNDER THE CONDITIONS OF THE RIGHT-BANK FOREST-STEPPE OF UKRAINE

The article is devoted to the study of the effect of foliar treatment of Tomatillo plants with the use of drugs of bacterial origin. The paper scientifically substantiates the influence of biologicals on the morphological and biometric parameters of the plant. It was investigated that the emergence of seedlings in varieties Lichtaryk and Pineapple was observed for 7-8 days. After diving and two treatments of plants with drugs, their positive effect on the growth and development of Tomatillo, especially in the phase of budding, flowering and fruiting. A short period of bud formation on the plant was characterized by a variety of Tomatillo Lantern from the use of Biomag. Thus, the beginning of the formation of buds occurred on 66 days on the Lantern variety. A similar effect of the biological product was found during the flowering phase and fruit set. As a result of the activity of Azotobacter chorococum bacteria, the growth and development phases of the Lantern variety are accelerated by 1-3 days compared to the control variant. The use of biological products has had a positive effect on the biometric parameters of the plant. When using bacteria p. Saccharomyces, Azotobacter chroococcum, Paenibacillus polymyxa, Enterobacter nimipressuralis, plant height and stem diameter depended on the type of biological product used. The height of the plant ranged from 82,8 cm to 89,6 cm in the variety Lantern and from 86,8 cm to 91,3 cm in the variety Pineapple. As a result of spraying the plants with Azotobacterin or Rostmoment, the height of the Tomatillo plant exceeded the height of the plant of the variant where biological products were not used. In these variants, the excess of plant height relative to the control was 8,2% for the variety Lantern and 4,3 % for the variety Pineapple, respectively. The diameter of the stem was in the range of 1,9-2,0 cm. Due to the activity of the bacteria Azotobacter chroococcum, Paenibacillus polymyxa, Enterobacter nimipressuralis or yeast p. Saccharomyces and products of their metabolism, revealed a positive effect of biologicals on the increase in leaf area and dry matter content of the leaf. As a result of cultivation of the cultivar Lichtarik and application of Rostmoment or Biopolitsid the area of leaves was at the level of 79,5 thousand м2/ha and 77,6 thousand м2/ha. Growth moment, for the cultivation of the variety Lantern, helped to increase the dry matter content of the leaf by 16,4 %. Treatment of Lantern plants with liquid humus-based concentrate Humisol provided the highest weight of Tomatillo fruit, which was at the level of 8,4 g, and the use of Humisol or Rostmoment for growing varieties Lantern and Pineapple increases the diameter of Tomatillo fruit by 6,9-10,3 %. Humisol, due to humic and fulvic acids, natural phytohormones affects the growth processes of the plant more intensively, which provided in the formation of the largest mass of fruits and their diameter. High yield is characterized by the Tomatillo variety Lantern with five applications of Humisol or Biopolicide, where its value is 33,3 t/ha and 32,0 t/ha. Key words: morphological features, biometric indicators, tomatillo, fruit yield, marketability.

The Effect of Growth Activators and Plant Growth-Promoting Rhizobacteria (PGPR) on the Soil Properties, Root Yield, and Technological Quality of Sugar Beet

The strategy “from farm to fork” assumes a reduction in the usage of fertilizers and plant protection products in EU agriculture. The aim of this study, conducted over the years 2017–2019 in several locations in Poland, is to evaluate the application of growth activators with and without plant growth-promoting rhizobacteria to reduce mineral nitrogen fertilization without negative effects on the root yield. We studied the effect of these activators on selected soil properties. The experimental treatments included the application of the growth activators Penergetic (K + P) and Azoter, which contains the bacteria Azotobacter chroococcum, Azospirillum brasilense, and Bacillus megaterium, before sowing or during vegetation. The nitrogen rates were reduced by 30% in comparison to full nitrogen mineral fertilization (control treatment). In selected experiments, the application of Penergetic and Penergetic with Azoter caused a higher content of nitrate nitrogen (N-NO3) and ammonium nitrogen (N-NH4) after the sugar beet harvest as well as higher contents of mineral nitrogen (Nmin), P, K, and Mg in the soil in comparison to the treatment with the full dose of mineral nitrogen fertilization. The obtained results proved that it was possible to reduce the mineral application of nitrogen by 30% without a decrease in the biological and pure sugar yield, and even with an increase in the sugar yield caused by the application of the growth activators Penergetic (K + P) and Azoter.

PRODUCTIVITY ENHANCEMENT OF CORIANDRUM SATIVUM USING PLANT BIOLOGICALS

Objective: The present study was designed to investigate phytopromotional effects of Sebacina vermifera on economically and medicinally important aromatic plant - Coriandrum sativum (coriander).
 Methods: Phytopromotional effects of Sebacina vermifera were evaluated on coriander, under greenhouse and field conditions. The evaluations were carried out with reference to emergence, growth promotion and quantitative as well as the qualitative composition of essential oil. Beside this the overall effects were comparatively assessed with the effects of (a) Phosphate solubilizing bacteria (Pseudomonas fluorescens) (b) Nitrogen-fixing bacteria (Azotobacter chroococcum) on coriander using same parameters.
 Results: Mycorrhizal fungus (Sebacina vermifera) was observed with the most significant effect in all aspects viz. emergence, growth promotion and quantitative as well as the qualitative composition of essential oil.
 Conclusion: Based upon the observations, Sebacina vermifera is highly recommended as a potential biological agent that could be applied for phytopromotional effects and economic cultivation of aromatic plants.

Interaction between graphene oxide and nitrogen-fixing bacterium Azotobacter chroococcum: Transformation, toxicity and nitrogen fixation

Nitrogen is an essential element and 80% of nitrogen fixation from atmosphere is achieved by biological nitrogen fixation. When graphene enters the environment, it would inevitably interact with nitrogen-fixing bacteria and might disturb the nitrogen cycle. Herein, the interaction between graphene oxide (GO) and nitrogen-fixing bacterium Azotobacter chroococcum was studied to reveal the potential impact of graphene materials on biological nitrogen fixation. After incubation with A. chroococcum, GO was separated, washed and characterized by different techniques. The toxicity of GO to A. chroococcum was monitored by colony-forming unit (CFU) counting, growth curve, live/dead staining and ultrastructural observations. The nitrogen fixation activity of A. chroococcum was measured by acetylene reduction assay and the soil nitrogen contents were measured. GO was immediately reduced by cell secretions and kept stable thereafter. GO stimulated A. chroococcum growth at low concentrations and showed inhibitive effect at high concentrations. GO induced cell death and cell wall break at high concentration. The toxicological mechanism was assigned to membrane damage and oxidative stress. In the presence of soil, GO showed similar concentration-dependent but alleviated toxicity, while the soil nitrogen contents slightly increased at high concentrations. Our results collectively indicated that GO was bio-reduced and toxic to nitrogen-fixation bacteria.

Biodiversity and Plant Growth Promoting Potential of Bacteria from Soybean Rhizosphere of Saline Soil

PGPR are root-associated bacteria that form symbiotic relationships with many plants. These are the Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria (PGPR). PGPR are highly diverse and are important in plant growth promotion and increase in yield of crops. Almost all of the PGPR bacteria produce phytohormones, some fixes atmospheric nitrogen, some solublizes the phosphates and some resist phytopathogens by production of siderophores. An understanding of microbial diversity is important in agricultural contest, it is important and useful to know soil quality in terms of PGPR bacteria which is helpful for taking measures for soil management and increased plant productivity. It is also important to understand the relationship of soil and plants with the diversity of associated bacteria for their better exploitation. Therefore, it is important to know the soil micro flora and their diversity. Most of the rhizospheric bacterial diversity from normal soil have been studied and organisms explored for their use as bioinoculents. However, saline soil rhizospheric microfloras remain unexplored. By considering this, in the present study fifty two bacterial isolates including PGPR have been isolated from saline soil of Kolhapur district of southern Maharashtra, India. Isolates were identified up to genus and species level. Few isolates were studied their nitrogen fixing and phosphate solublizing activity. Present study showed that amongst nitrogen fixing bacteria Azotobacter chroococcum found to be most dominant and Bacillus megaterium was found to be most dominant phosphate solublizer. Study indicated the importance of these organism as bioinoculents for saline soil and can be explored for biofertilizer production.

Genetic, structural, and functional diversity of low and high-affinity siderophores in strains of nitrogen fixing Azotobacter chroococcum.

To increase iron (Fe) bioavailability in surface soils, microbes secrete siderophores, chelators with widely varying Fe affinities. Strains of the soil bacterium Azotobacter chroococcum (AC), plant-growth promoting rhizobacteria used as agricultural inoculants, require high Fe concentrations for aerobic respiration and nitrogen fixation. Recently, A. chroococcum str. NCIMB 8003 was shown to synthesize three siderophore classes: (1) vibrioferrin, a low-affinity α-hydroxy carboxylate (pFe = 18.4), (2) amphibactins, high-affinity tris-hydroxamates, and (3) crochelin A, a high-affinity siderophore with mixed Fe-chelating groups (pFe = 23.9). The relevance and specific functions of these siderophores in AC strains remain unclear. We analyzed the genome and siderophores of a second AC strain, A. chroococcum str. B3, and found that it also produces vibrioferrin and amphibactins, but not crochelin A. Genome comparisons indicate that vibrioferrin production is a vertically inherited, conserved strategy for Fe uptake in A. chroococcum and other species of Azotobacter. Amphibactin and crochelin biosynthesis reflects a more complex evolutionary history, shaped by vertical gene transfer, gene gain and loss through recombination at a genomic hotspot. We found conserved patterns of low vs. high-affinity siderophore production across strains: the low-affinity vibrioferrin was produced by mildly Fe limited cultures. As cells became more severely Fe starved, vibrioferrin production decreased in favor of high-affinity amphibactins (str. B3, NCIMB 8003) and crochelin A (str. NCIMB 8003). Our results show the evolution of low and high-affinity siderophore families and conserved patterns for their production in response to Fe bioavailability in a common soil diazotroph.

Responses of Bruguiera sexangula propagules to beneficial microbes in the nursery

Bruguiera sexangula (Lour) Poir., a threatened mangrove tree, was inoculated with beneficial microbes in a nursery to assess any improvements in growth and biomass. From soil samples from the rhizosphere of B. sexangula in a mangrove forest in Panangadu of Kerala India, nitrogen-fixing bacteria Azotobacter chroococcum and Azospirillum brasilense were isolated. The phosphate-solubilising bacterium Bacillus megaterium and potassium-mobilizing bacteria Frateruria aurantia were also isolated and cultured on suitable media. Later, ripe propagules of B. sexangula were collected from matured trees and raised in sterilized soil bags (13 × 25 cm) containing sterilized soil and sand (2:1 ratio). The cultured beneficial microbes were propagated and used to inoculate the ripe propagules of B. sexangula and maintained in the nursery for 6 months. After 6 months, growth and biomass of the inoculated propagules were greater than for the uninoculated control propagules. Shoot length, number of leaves, stem girth and root length were also significantly greater than in the controls. This study showed that the mangrove-specific beneficial microbes influenced the growth of B. sexangula in the nursery and will help in the establishment of B. sexangula in degraded mangrove forests.

Biofertilizer effect of free living nitrogen fixing bacterium on the growth and water quality properties of Penaeid prawn culture system

The role of phytoplankton is significant in improving the yield of prawn culture. The growth of phytoplankton will be effected various factors viz. dissolved oxygen, production of natural food to shrimp larvae in control of ammonia. The growth of phytoplankton can be enhanced by application of nitrogeneous fertilizers to improve water quality and growth performance of Penaeus indicus. The present research work is focussed on a free-living nitrogen fixing bacterium Azotobacter chroococcum supplemented by nitrogeneous fertilizers to increase the content of proteins, carbohydrates and wet weight of P. indicus. Ten animals of juveniles of P. indicus were collected and grown in controlled conditions for fifteen days. The liquid suspension of free living nitrogen fixing bacteria A. chroococcum has been inoculated for experimental treatment purpose. The inoculum has been introduced to four treatments and for findings of water quality analysis andphytoplankton growth analysis by Strickland and Parsons method and biochemical analysis by Raymont et al., method. The research findings revealed that A. chroococcum supplemented with fertilizers will affect the growth of phytoplankton which is vital in prawn culture and enhance the growth of hormones and dry weight for improvement of the yield.

Characterization of the Paenibacillus beijingensis DSM 24997 GtfD and its glucan polymer products representing a new glycoside hydrolase 70 subfamily of 4,6-α-glucanotransferase enzymes.

Previously we have reported that the Gram-negative bacterium Azotobacter chroococcum NCIMB 8003 uses the 4,6-α-glucanotransferase GtfD to convert maltodextrins and starch into a reuteran-like polymer consisting of (α1→4) glucan chains connected by alternating (α1→4)/(α1→6) linkages and (α1→4,6) branching points. This enzyme constituted the single evidence for this reaction and product specificity in the GH70 family, mostly containing glucansucrases encoded by lactic acid bacteria (http://www.CAZy.org). In this work, 4 additional GtfD-like proteins were identified in taxonomically diverse plant-associated bacteria forming a new GH70 subfamily with intermediate characteristics between the evolutionary related GH13 and GH70 families. The GtfD enzyme encoded by Paenibacillus beijingensis DSM 24997 was characterized providing the first example of a reuteran-like polymer synthesizing 4,6-α-glucanotransferase in a Gram-positive bacterium. Whereas the A. chroococcum GtfD activity on amylose resulted in the synthesis of a high molecular polymer, in addition to maltose and other small oligosaccharides, two reuteran-like polymer distributions are produced by P. beijingensis GtfD: a high-molecular mass polymer and a low-molecular mass polymer with an average Mw of 27 MDa and 19 kDa, respectively. Compared to the A. chroooccum GtfD product, both P. beijingensis GtfD polymers contain longer linear (α1→4) sequences in their structure reflecting a preference for transfer of even longer glucan chains by this enzyme. Overall, this study provides new insights into the evolutionary history of GH70 enzymes, and enlarges the diversity of natural enzymes that can be applied for modification of the starch present in food into less and/or more slowly digestible carbohydrate structures.

Systemic effect of microbial preparations on causative microorganisms of bacterial diseases of tomato plants

Biologicals Phytohelp, Phytocide and Ekstrasol, based on the bacteria Bacillus subtilis, showed different antibacterial activity to phytopathogens, due to the peculiarities of used strains, cells titer and concentration of biologically active products of microorganisms. Biologicals Phytohelp and Phytocide showed high antibacterial activity against the agents of bacterial cancer C. michiganensis subsp. michiganensis and bacterial black spotting X. vesicatoria, and the no growth zone diameter ranged from 73 to 80 mm. Under these conditions no growth zone diameter of the studied strains C. michiganensis subsp. michiganensis and X. vesicatoria for microbiological preparation Ekstrasol did not exceed 40 mm. Among these preparations more active against bacterial speck of tomatoes P. syringae pv. tomato was microbial preparation Ekstrasol no growth zone diameter of which was 23±3.0 mm. Biological Azotofit, based on cells of nitrogen-fixing bacteria Azotobacter chroococcum, showed high antibacterial activity against the agent of bacterial cancer C. michiganensis subsp. michiganensis, no growth zone diameter was 78±2.0 mm. This preparation was middle-active against the agent of bacterial black spotting X. vesicatoria and showed no activity against the agent of bacterial speck of tomato P. syringae pv. tomato. It was revealed that the most active against the agents of bacterial black spotting and bacterial cancer are biologicals Phytocide and Phytohelp, based on the bacteria Bacillus subtilis that are recommended by us for use in the manufacture.