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Plant Growth Promoting Rhizobacteria
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Mohd. Musheer Altaf, Mohd Sajjad Ahmad Khan
Biofilm development by root-inhabiting microorganisms might participate in vital functions in the defense of the plant in addition to the bacteria. Improved tolerance to drought stress is observed among those plants colonized through definite bacteria (Kim et al., 2012; Naylor and Coleman-Derr, 2018). It is recognized that EPS creates the biofilm and retains moisture coating on the root region and mitigates drought stress impact within plants (Kaushal and Wani, 2016). Famine could stimulate surviving microorganisms to create a mixture of components that influenced population strength, for example, drought supported soils possesses additional antibiotics, which are assumed to be formed by drought-tolerant bacteria as a physiological reply to outnumber other bacteria for restricted nutrients, or probably as indications to encourage drought reaction methods like biofilm development (Bouskill et al., 2016). Timmusk et al. (2015) reported that a mutant of Paenibacillus polymyxa deficient in Sfptype 40-phosphopantetheinyl transferase had increased biofilm creation, which upon treatment to drought-stressed wheat plants was revealed to improve plant endurance and biomass creation two to three times, respectively. The methods through which biofilm development assists in plant defense are at the exploratory phase. The construction of the hydrated medium of the biofilm might develop water withholding capacity to preserve equally microbial and plant cell performance under drought (Bouskill et al., 2016). Additionally, the hydrated biofilm medium, during the limitation of dispersion, could aggregate microbial metabolism products, for instance osmolytes or biocontrol-active organizations, for a larger influence on plants as inducers of systemic stress tolerance and as limiting factor for other rhizobacteria (Wright et al., 2016). Kasim et al. (2016) established that the treatment by means of the biofilm forming PGPR (Bacillus amyloliquefaciens) had improved impact on the development of barley plants cultivated in high salt conditions and accomplished that the bacteria might be useful in supporting barley plants to bear salt stress next to its function in growth encouragement. Zubair et al (2019) accounted that the biofilm creating capability of psychrophilic PGPR Bacillus is a distinctive feature facilitating them to stay alive and create vital metabolic products under low-temperature stress. This capability is associated with the prospective of inoculated bacteria to inhabit plant roots and assist the plants in lessening low-temperature stress.
The purification and functional study of new compounds produced by Escherichia coli that influence the growth of sulfate reducing bacteria
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Oluwafemi Adebayo Oyewole, Julian Mitchell, Sarah Thresh, Vitaly Zinkevich
Several studies have described some inhibitors of SRB growth that are derived from bacteria; for example, Jayaraman et al. [69] and Zuo [29] reported that indolicidin, bactenecin, and polymyxin produced by Paenibacillus polymyxa are capable of inhibiting SRB growth. Bacillus brevis produces a compound referred to as gramicidin-S that inhibits the growth of Desulfovibrio orientis, D. vulgaris and D. gigas [29,31,70] and thereby reduced corrosion caused by the SRB. In addition, Bacillus licheniformis secretes γ-polyglutamate and polyaspartate that reduce SRB growth [29,71,72]. The mechanism of SRB growth prevention by these organisms has been suggested and include either the production of antimicrobial agents [29,73] or attack on the adenosine 5ʹ- phosphosulphate (APS) and bisulfate reductase (DSR) responsible for hydrogen sulfide production in SRBs [14]. Similarly, the SGE may function in SRB induction by increasing their growth rate while the SGI may function by causing damage in the cells as observed in this study. The MALDI-TOF spectra showed the presence of low molecular weight compounds in the range of 1700 Da for SGE and 2400 Da for SGI. The spectra showed equal and repeating units of ~213 m/z between the peaks. According to Wallace and Guttman [74], the equal and repeating units are characteristic spectra of condensation homopolymers. MALDI-TOF spectra revealed that the compounds are small molecular weight biomolecules and that the two molecules are very closely related.
Application of differential bio-flocculation in the removal of hematite and goethite from kaolin and quartz
Published in Chemical Engineering Communications, 2019
Mohammad Raouf Hosseini, Ataallah Bahrami, Ali Ahmadi, Mohammad Reza Azizinia, Ebrahim Azimi
Iron impurities mainly exist in kaolin and quartz as hematite, goethite, magnetite, ilmenite, and pyrite (Lu et al., 2017). Biological removal of iron from clays has been examined using iron reducing bacteria and acid producing heterotroph microbes (Hosseini and Ahmadi, 2015). However, recently some researchers (Deo and Natarajan, 1998; Sarvamangala and Natarajan, 2011; Selim and Rostom, 2017) investigated the selective separation of hematite from silica or kaolinite through microbiologically induced flotation and flocculation by Bacillus subtilis, Paenibacillus polymyxa, and Bacillus cereus. Also, Yang et al. (2013) did research on Rhodococcus erythropolis cells as a bioflotation collector for hematite, quartz, kaolinite, and apatite system. Flocculation behavior of hematite–kaolinite dispersion in the presence of extracellular proteins and polysaccharides of B. subtilis was investigated by Poorni and Natarajan (2013, 2014). Furthermore, Lin et al. (2016) studied the adsorption of EPS from Pseudomonas putida on montmorillonite, kaolinite, and goethite as a function of pH using confocal laser scanning microscopy and isothermal titration calorimetry.
Fusion of the Microbial World into the Flotation Process
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Derya Öz Aksoy, Serhat Özdemir, Pınar Aytar Çelik, Sabiha Koca, Ahmet Çabuk, Hüseyin Koca, Pablo Brito-Parada
Activators: Another type of reagent included in the “regulators” group are activators. Bioactivators are thus bioreagents that are used before collectors and that increase flotation efficiency. As an example, a study published by Deo and Natarajan used the bacteria Paenibacillus polymyxa as a bioactivator to increase quartz flotation efficiency (Deo and Natarajan 1998). (Table 3) summarizes the bioflotation studies in the literature using bioreagents as activators.