Assessment of zinc solubilization potential of zinc-resistant Pseudomonas oleovorans strain ZSB13 isolated from contaminated soil

Zinc is an essential micronutrient that is required for optimum plant growth. It is present in soil in insoluble forms. Bacterial solubilization of soil unavailable form of Zn into available form, is an emerging approach to alleviate the Zn deficiency for plants and human beings. Zinc solubilizing bacteria (ZSB) could be a substitute for chemical Zn fertilizer. The present study aimed to isolate and characterize bacterial species from the contaminated soil and evaluate their Zn solubilizing potential. Zn resistant bacteria were isolated and evaluated for their MIC against Zn. Among the 13 isolated bacterial strains ZSB13 showed maximum MIC value upto 30mM/L. The bacterial strain with the highest resistance against Zn was selected for further analysis. Molecular characterization of ZSB13 was performed by 16S rRNA gene amplification which confirmed it as Pseudomonas oleovorans. Zn solubilization was determined through plate assay and broth medium. Four insoluble salts (zinc oxide (ZnO), zinc carbonate (ZnCO3), zinc sulphite (ZnS) and zinc phosphate (Zn3(PO4)2) were used for solubilization assay. Our results shows 11 mm clear halo zone on agar plates amended with ZnO. Likewise, ZSB13 showed significant release of Zn in broth amended with ZnCO3 (17 and 16.8 ppm) and ZnO (18.2 ppm). Furthermore, Zn resistance genes czcD was also enriched in ZSB13. In our study, bacterial strain comprising Zn solubilization potential has been isolated that could be further used for the growth enhancement of crops.

Growth Enhancement, Uptake of N, P, K Nutrients and Production of Maize in an Entisol of Kalidawir, Tulungagung due to Application of Cow Manure Fertilizer and NPK Fertilizer

Entisols are newly formed soil types and are commonly found in Indonesia, with a distribution of ±3 million ha distribution. Entisol Kalidawir has a slightly acidic pH value of 5.8 and contains very low total-nitrogen (N) and available-phosphorus (P) nutrients, calcium (Ca), sodium (Na) and magnesium (Mg) in the exchangeable base are also low and clay loam texture. Low soil nutrients and organic matter can have an impact on plant growth and production Maize is one of the most widely cultivated food crops in Indonesia. The purpose of this study was to analyze various doses of the combination of cow manure and NPK fertilizer on N, P and potassium (K) uptake, growth and production of maize. The results showed that the application of 20 t ha-1 of cow manure and 400 kg ha-1 of NPK fertilizer at observations 27 and 54 days after planting increased growth in height and number of leaves of corn plants and increased nutrient uptake of N, P, and K, respectively. Also reached 1, 0.14, and 0.82 g plant-1 and 5.52, 0.83, and 5.11 g plant-1. In addition, it produces the highest corn production of 10.53 t ha-1.

Isolation and Characterization of Plant Growth Promoting Rhizobacteria for Growth Promotion of Rice (Oryza sativa L.) and Wheat (Triticum aestivum)

The use of rhizobacteria for plant growth enhancement is decades old. Still, in this era of the 21st century, biofertilizers have become the need of the day due to the health and environmental concerns associated with chemical fertilizers and pesticides. Rhizobacteria strains were isolated from the rhizosphere of rice and wheat. The selected bacterial strains' nitrogen fixation, indole acetic acid (IAA) production, phosphorus solubilization, and antifungal activity were determined on morphological, biochemical, and molecular levels. Production of IAA ranged from 6 µg/ml to 29.33 µg/ml. Ethylene production (C2H4/hr) varied from 2 µmoles to 9.8 µmoles. Maximum Phosphorus Solubilization index (7), decrease in pH (4) and Solubilization % age (0.49) was observed in WM-2 (wheat microbe). Promising results were obtained concerning antifungal activity against Rhizoctonia solani and Fusarium sp. The effect of the potential PGPR strains on the germination of rice and wheat was significantly positive in Petri plates. In the case of rice, the highest shoot length (29.27 cm) was observed by inoculation with RPR-33 (Rice isolate), and the most increased root length (9.33 cm) was observed in the treatment inoculated with RPR-42. The highest shoot fresh weight (476.67 mg/plant) was recorded in the treatment inoculated with RPR-42. The maximum root weight was 170 mg/plant in the same treatment. For wheat, all recorded growth parameters were improved significantly by wheat microbe WM-5. All the PGPR isolates showed positive results for growth parameters of wheat and rice on inoculation. So, it is suggested that these PGPR isolates may be used in potential biofertilizers.

Biosynthesis Pathways, Transport Mechanisms and Biotechnological Applications of Fungal Siderophores

Iron (Fe) is the fourth most abundant element on earth and represents an essential nutrient for life. As a fundamental mineral element for cell growth and development, iron is available for uptake as ferric ions, which are usually oxidized into complex oxyhydroxide polymers, insoluble under aerobic conditions. In these conditions, the bioavailability of iron is dramatically reduced. As a result, microorganisms face problems of iron acquisition, especially under low concentrations of this element. However, some microbes have evolved mechanisms for obtaining ferric irons from the extracellular medium or environment by forming small molecules often regarded as siderophores. Siderophores are high affinity iron-binding molecules produced by a repertoire of proteins found in the cytoplasm of cyanobacteria, bacteria, fungi, and plants. Common groups of siderophores include hydroxamates, catecholates, carboxylates, and hydroximates. The hydroxamate siderophores are commonly synthesized by fungi. L-ornithine is a biosynthetic precursor of siderophores, which is synthesized from multimodular large enzyme complexes through non-ribosomal peptide synthetases (NRPSs), while siderophore-Fe chelators cell wall mannoproteins (FIT1, FIT2, and FIT3) help the retention of siderophores. S. cerevisiae, for example, can express these proteins in two genetically separate systems (reductive and nonreductive) in the plasma membrane. These proteins can convert Fe (III) into Fe (II) by a ferrous-specific metalloreductase enzyme complex and flavin reductases (FREs). However, regulation of the siderophore through Fur Box protein on the DNA promoter region and its activation or repression depend primarily on the Fe availability in the external medium. Siderophores are essential due to their wide range of applications in biotechnology, medicine, bioremediation of heavy metal polluted environments, biocontrol of plant pathogens, and plant growth enhancement.

From Blood to Bone—The Osteogenic Activity of L-PRF Membranes on the Ex Vivo Embryonic Chick Femur Development Model

(1) Background: To evaluate the effects of the direct and indirect contact of leukocyte and platelet-rich fibrin (L-PRF) on bone development, in an ex vivo embryonic chick femur model. (2) Methods: Both sections of L-PRF membranes (red and yellow portions) were evaluated with scanning electron microscopy and histochemical staining. The in vivo angiogenic activity was evaluated using a chorioallantoic membrane model. The osteogenic activity was assessed with an organotypic culture of embryonic chick femora through direct and indirect contact, and assessment was conducted by microtomographic and histological analysis. Descriptive statistics, One-Way ANOVA and Tukey’s multiple comparisons tests were performed for datasets that presented a normal distribution, and Kruskal-Wallis tests were performed for non-parametric datasets. A significance level of 0.05 was considered. (3) Results: The L-PRF induced angiogenesis reflected by a higher number and a larger and more complex gauge in the vessels that invaded the membrane. The physical presence of the membrane over the bone (direct contact) unleashes the full potential of the L-PRF effects on bone growth enhancement. The greatest increase in mineral content was observed in the diaphysis region. (4) Conclusion: The L-PRF direct contact group presented higher values on mineral content for bone volume, bone surface and bone mineral density than the indirect contact and control groups.

Root-Derived Endophytic Diazotrophic Bacteria Pantoea cypripedii AF1 and Kosakonia arachidis EF1 Promote Nitrogen Assimilation and Growth in Sugarcane

Excessive, long-term application of chemical fertilizers in sugarcane crops disrupts soil microbial flora and causes environmental pollution and yield decline. The role of endophytic bacteria in improving crop production is now well-documented. In this study, we have isolated and identified several endophytic bacterial strains from the root tissues of five sugarcane species. Among them, eleven Gram-negative isolates were selected and screened for plant growth-promoting characteristics, i.e., production of siderophores, indole-3-acetic acid (IAA), ammonia, hydrogen cyanide (HCN), and hydrolytic enzymes, phosphorus solubilization, antifungal activity against plant pathogens, nitrogen-fixation, 1-aminocyclopropane-1-carboxylic acid deaminase activity, and improving tolerance to different abiotic stresses. These isolates had nifH (11 isolates), acdS (8 isolates), and HCN (11 isolates) genes involved in N-fixation, stress tolerance, and pathogen biocontrol, respectively. Two isolates Pantoea cypripedii AF1and Kosakonia arachidis EF1 were the most potent strains and they colonized and grew in sugarcane plants. Both strains readily colonized the leading Chinese sugarcane variety GT42 and significantly increased the activity of nitrogen assimilation enzymes (glutamine synthetase, NADH glutamate dehydrogenase, and nitrate reductase), chitinase, and endo-glucanase and the content of phytohormones gibberellic acid, indole-3-acetic acid, and abscisic acid. The gene expression analysis of GT42 inoculated with isolates of P. cypripedii AF1 or K. arachidis EF1 showed increased activity of nifH and nitrogen assimilation genes. Also, the inoculated diazotrophs significantly increased plant nitrogen content, which was corroborated by the 15N isotope dilution analysis. Collectively, these findings suggest that P. cypripedii and K. arachidis are beneficial endophytes that could be used as a biofertilizer to improve plant nitrogen nutrition and growth of sugarcane. To the best of our knowledge, this is the first report of sugarcane growth enhancement and nitrogen fixation by Gram-negative sugarcane root-associated endophytic bacteria P. cypripedii and K. arachidis. These strains have the potential to be utilized as sugarcane biofertilizers, thus reducing nitrogen fertilizer use and improving disease management.

Use of Bacillus Subtilis Probiotics as Non-Antibiotic Gut Modulator and Growth Promoter in Broiler Chickens

Wide range of Antibiotics is being used as feed additives in Animal industry in order to get rid from pathogens and as growth promoters in developing world. But after the suggested prohibition on using antibiotics, products such as probiotics are getting substantial importance in nutrition because of their non-resistant and non-residual possessions. Basic aim of the chapter is to highlight fruitful effects of Bacillus Subtilis as non-antibiotic gut modulator and growth promoter in broiler chickens. Probiotics are the living culture of microorganisms. They flourish in the gut of the host and fortify the growth of valuable commensals in the digestive tract by minimizing the destruction triggered by pathogens, boost up the immune system, supporting the integrity of the gut mucosa and maintain a stability and balance of normal microflora. Probiotics can be used as best substitute to conventional antimicrobial therapy. In addition, it has been observed that probiotics plays a role in growth enhancement by augmenting useful enzymes in the body and promote the growth of other normal commensals such as Lactobacillus and having effect on gut luminal pH. Probiotics are quite active against intestinal pathogens in several ways, viz. including improved immune elimination, competing for mucosal attachment, striving for crucial nutrients, or producing antimicrobial complexes contrary to numerous enteropathogens. It can be concluded that B. Subtilis has the ability to modulate gut and immune system histophysiology and histomorphology and can be used as safe antimicrobial candidate in poultry nutrition. Knowledge of such possessions of the B. Subtilis as probiotics and the mechanisms of action may enable the researchers to manipulate the use of such alternatives for better growth production, and safe and healthy poultry industry.

Dissolution of Biofilm Secreted by Three Different Strains of Pseudomonas aeruginosa with Bromelain, N-Acetylcysteine, and Their Combinations

Bacterial infection of hernia mesh with the formation of biofilms presents a barrier to antibiotic treatment with subsequent surgical intervention and hospitalization. Hence, in the current study, we examined the effect of BromAc, a mucolytic agent, on the dissolution of biofilm formed by three different strains of Pseudomonas aeruginosa. Pseudomonas aeruginosa was carefully grown on hernia mesh and treated with various concentrations of bromelain, NAC, and their combinations at 37 °C over 4 h in vitro. Then, the biofilm dissolution activities of the agents were evaluated. Moreover, the combination index (CI) was analyzed to determine the synergy of the bromelain and NAC combination. The results indicated that biofilms were more susceptible to degradation by bromelain, whilst NAC showed growth enhancement in two of the strains. However, in combination (BromAc), the three strains were dramatically affected by the agents, with more than 80% debridement fir a suitable combination of bromelain and NAC that was also strain-specific. Hence, the current study shows that the biofilms formed by these three strains of Pseudomonas aeruginosa were adversely affected by a single treatment of BromAc, with more than 80% debridement, indicating that subsequent treatment may abolish the biofilm completely.