Exploiting of honey-associated Bacillus strains as plant-growth promoting bacteria for enhancing barley growth in rare earth tailings

Abstract

In the coming decades, exploitation of plant growth promoting bacteria (PGPB) will be a major trend in sustainable agriculture. Except for rhizobacteria, the bacteria inhabiting the non-rhizosphere could be considered the supplementary microbial source to exploit PGPB. Rare earth tailings soil (RETS) has caused a serious threat to sustainable agriculture due to excessive aluminum (Al) toxicity under acidic condition (pH<5.5). The efficient restoration strategy is to combine phytoremediation and PGPB. The aim of this work was to screen honey-associated Bacillus strains as PGPB to improve barley (Hordeum vulgare L.) growth in RETS. Nine Bacillus strains from honey were initially selected with higher tolerance to acid (pH 4.0) and Al stress (1.5 mM). Only six strains among these nine strains could produce ACC deaminase. The nine strains were all efficient in dissolving phosphate, producing organic acid, siderophore, and IAA. The nine strains could promote barley seedlings growth mainly via production of organic acid, ACC deaminase. However, this growth promotion was weakened slightly by siderophore and phosphate solubilization under acidic condition. On the whole, inoculation with the nine strains obviously enhanced barley seedlings growth in RETS. Thus, the nine honeyassociated Bacillus strains could be exploited as PGPB to enhance barley growth in RETS.

Bacterial Rhizoplane Colonization Patterns of Buchloe dactyloides Growing in Metalliferous Mine Tailings Reflect Plant Status and Biogeochemical Conditions

“…Root exudates consisting of organic compounds such as polysaccharides, sugars, amino acids, and fatty acids [18,19,20,21] create the “rhizosphere effect” that is characterized by a 10- to 100-fold greater abundance of microbes in the rhizosphere as compared to the bulk soil [22]. Previous research does indicate that rhizosphere bacteria, specifically plant growth promoting bacteria (PGPB), are particularly important for plant growth and establishment under extreme conditions of the mine tailings environment [14,15,23,24,25,26,27]. PGPB enhance plant growth by 1) increasing nutrient availability through phosphorous solubilization, production of iron-chelating siderophores, and nitrogen fixation; 2) decreasing the plant-stress hormone ethylene through production of ethylene-cleaving ACC (1-aminocyclopropane-1-carboxylate) deaminase; 3) providing protection from pathogens; and 4) decreasing metal bioavailability to plants [28,29,30].…”

Hydrogen Peroxide-Resistant CotA and YjqC of Bacillus altitudinis Spores Are a Promising Biocatalyst for Catalyzing Reduction of Sinapic Acid and Sinapine in Rapeseed Meal

“…Our previous work also strongly suggested that B . altitudinis hb4 was highly resistant to H 2 O 2 [ 32 , 33 ]. The enhanced resistance of B .…”

“…M2015018). The strain was isolated from gall honey (the honeybee Apis cerana collected nectar from gall flowers), which was purchased from Apiary of Ba Ma Mi Yuan Co. Ltd., Bama, China [ 32 , 33 ]. According to reports, an appropriate concentration of Mn 2+ was often used for promoting Bacillus sporulation [ 34 ].…”

Isolation and characterization of a novel gossypol-degrading bacteria Bacillus subtilis strain Rumen Bacillus Subtilis

“…DNA was extracted using the sodium dodecyl sulfate (SDS)-proteinase K method [ 20 ] and purified DNA samples were stored at −20°C. The genomic DNA was amplified by polymerase chain reaction (PCR) using universal primers F1: 5′-AGAGTTTGATCCTGGCTCAG-3′ and R1: 5′-ACGGTTACCTTGTTACGACTT-3′ [ 21 ] and the PCR reaction was conducted using the following conditions: 5 min at 94°C, followed by 35 cycles of 30 s at 94°C, 30 s at 56°C, and 90 s at 72°C, and a final extension of 10 min at 72°C. The isolated strain 16S rRNA genes were sequenced by Shanghai Huada, China.…”