Isolation and Identification of Zinc Dissolving Bacteria and Their Potential on Growth of Zea mays

Abstract

WENTY-FIVE bacterial isolates were isolated from mature …… compost and evaluated for their solubilization potential of insoluble zinc oxide and zinc carbonate. An efficient zinc-solubilizing bacterial isolate (Zn14) were chosen. Thereafter, some morphological and biochemical characteristics as well as 16S rRNA sequence indicated that the isolate belonged to Enterobacter cloacae. The effect of various carbon and nitrogen sources on the efficiency of Zn solubilization were investigated under shaking and static conditions. The selected bacterial strain could solubilize Zn compounds under a wide range of nutrient types. A pot experiment was conducted at Sakha Agricultural Research Station, Sakha, Kafrelsheikh, Egypt to study the efficiency of using Enterobacter cloacae as an in vivo Zn solubilizer either alone or with amended zinc compounds (ZnO and ZnCO 3) to the soil and its effect on growth parameters of Zea mays under sterile and non-sterile soil at the age of 30 and 60 days. There was a highly significant response for increased Zn uptake in all treatments compared to the control. The treatment with ZnO and E. cloacae was the more effective in terms of total chlorophyll plant dry weight compared to the control. To solve zinc nutrition problem using a biofertilizer, it is obvious that E. cloacae is capable of solubilizing insoluble zinc compounds by inoculation to increase crop growth and improve soil fertility.

Cross Talk Between Zinc-Solubilizing Bacteria and Plants: A Short Tale of Bacterial-Assisted Zinc Biofortification

“…Bacillus, in particular, showed a profound role in Zn biofortification in numerous food crops (8,12,38,55,58,(167)(168)(169)(170)(171)(172). The important crops such as maize (38,54,58,173,174), rice (59,60,171,175,176), and wheat (8,11,31,32,167,177) have been studied extensively for Zn biofortification in response to ZSB inoculants as the grain parts from these crops offer the most important staple foods on a broad scale worldwide. A potential ZSB microbial strain, namely Bacillus sp.…”

“…ZSB with Zn source supplementation such as ZnO, ZnSO4 also provided fruitful benefits of promoting plant growth, soil health, and Zn biofortification. (174) reported the enhancement in plant growth and soil fertility under the response of a bioinoculant (E. cloacae) and Zn supplement (ZnO). Moreover, the rice plant growth was improved by Acinetobacter sp.…”

Biofertilizer effect of some zinc dissolving bacteria free and encapsulated on Zea mays growth

“…Twenty bacterial isolates of different morphology were selected after using proper dilutions from each soil sample through serial dilution on modified Bunt and Rovira medium containing gl −1 [0.4 KH 2 PO 4 , 0.5 (NH 4 ) 2 SO 4 , 0.5 MgSO 4 ·7H 2 O, 0.1 MgCl 2 , 0.1 FeCl 3 , 0.1 CaCl 2 , 1.0 peptone, 1.0 yeast extract, 5.0 glucose, 250.0 ml soil extracts, 20.0 g agar, 750.0 ml tap water, pH 7.0], as well as 0.1% insoluble ZnO and ZnCO 3 as described by Saravanan et al ( 2003 ). Bacterial isolates with high growth and clear halo zone were selected, purified, and preserved in 40% glycerol at −20 ℃ (Omara et al 2016 ).…”

“…The bacterial isolates were spotted on media in triplicate and incubated at 28 ℃ for 5 days to check for clear halo zones. By measuring the colony and halo zone diameter, hydrolysis capacity (HC) was calculated as follows: diameter of clear zone/diameter of colony (Omara et al 2016 ).…”

“…Sequences used in the phylogenetic analysis were obtained from the RDP and GenBank databases. A phylogenetic tree was constructed using the neighbour-joining method (Omara et al 2016 ).…”