Zinc solubilizing Bacillus spp. potential candidates for biofortification in maize

Abstract

Bioaugmentation of Zn solubilizing rhizobacteria could be a sustainable intervention to increase bioavailability of Zn in soil which can be helpful in mitigation of yield loss and malnutrition of zinc. In present study, a number of pure rhizobacterial colonies were isolated from maize rhizosphere and screened for their ability to solubilize zinc oxide. These isolates were screened on the basis of zinc and phosphate solubilization, IAA production, protease production, catalase activity and starch hydrolysis. All the selected isolates were also positive for oxidase activity (except ZM22), HCN production (except ZM27) and utilization of citrate. More than 70% of isolates produces ammonia, hydrogen cyanide, siderophores, exopolysaccharides and cellulase. More than half of isolates also showed potential for urease activity and production of lipase. The ZM31 and S10 were the only isolates which showed the chitinase activity. All these isolates were evaluated in a jar trial for their ability to promote growth of maize under axenic conditions. Results revealed that inoculation of selected zinc solubilizing rhizobacterial isolates improved the growth of maize. In comparison, isolates ZM20, ZM31, ZM63 and S10 were best compared to other tested isolates in stimulating the growth attributes of maize like shoot length, root length, plant fresh and dry biomass. These strains were identified as Bacillus sp. (ZM20), Bacillus aryabhattai (ZM31 and S10) and Bacillus subtilis (ZM63) through 16S rRNA sequencing. This study indicated that inoculation of Zn solubilizing strains have potential to promote growth and can be the potential bio-inoculants for biofortification of maize to overcome the problems of malnutrition.

Screening of beneficial bacteria associated with Calophyllum brasiliense Cambess so as to develop microbial inoculants for agriculture

“…A total of 25 isolates from C. brasiliensis tissues and the rhizosphere presented ability to solubilize zinc in the qualitative test, of which eight presented halo diameters greater than or equal to 13 mm. This result is similar to that reported by Ramesh et al (2014) and Mumtaz et al(2017) in studies involving zinc solubilization by bacteria belonging to the genus Bacillus. In quantitative measurement, the isolates AP-JNFb-3-2, RHI-JMVL-3-1 and RHI-LGP-3-1, closely related to bacteria belonging to the genera Pseudomonas and Enterobacter, presented the greatest solubilization potential with zinc content in the media between 142.9 and 147.8 µg mL -1…”

“…. Mumtaz et al(2017) also reported higher IAA production by bacterial endophyte isolates from rice seeds (between 11.5 to 38.8 µg mL ), respectively. On other hand, Tsavkelova et al(2005aTsavkelova et al( , 2007b showed that the quantities of IAA secreted in the liquid culture by bacteria isolated from tropical orchids varied from 0.5 to 92.9 μg mL -1 .…”

Production and Implication of Bio-Activated Organic Fertilizer Enriched with Zinc-Solubilizing Bacteria to Boost up Maize (Zea mays L.) Production and Biofortification under Two Cropping Seasons

“…Several previous studies also indicate an enhancement in different crop growth and yield inoculated with plant growth-promoting bacterial strains [33,48,[50][51][52][53][54]. Additionally, improved root growth, which enhanced the overall plant growth owing to the well-acquisition of water and nutrients from the soil have also resulted in better growth and yield of the plants.…”

“…Recently, it is reported that ZSB alone and with organic matter is involved in the bio-activation of ZnO and enriched cereal grains with Zn [33]. In such a way, ZSB can be exploited to mobilize unavailable Zn and promote plant growth and yield through Zn assimilation [33,48,49]. In the present study, four BOZ formulations were produced by enriching the ZnO-orange peel waste composite with ZSB: Bacillus sp.…”

Genome Insights of the Plant-Growth Promoting Bacterium Cronobacter muytjensii JZ38 With Volatile-Mediated Antagonistic Activity Against Phytophthora infestans

“…Zinc (Zn) is another micronutrient which is important for metabolic enzyme systems and optimal plant growth and development (Brown et al, 1993). Zn deficiency is well reported in soils around the world and is a commonly occurring problem in crop plants, leading to decreases in crop yield and nutritional quality (White and Zasoski, 1999;Mumtaz et al, 2017). Similar to P and Fe, Zn is also inaccessible to plants due to its low solubility where it is found in different forms in soil (e.g., Smithsonite/ZnCO 3 ) and its solubility is highly dependent on pH (higher solubility at low pH) (Martínez and Motto, 2000;Vodyanitskii, 2010).…”