Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings, China

To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria（PGPB）. It shows that： Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF（Cation Diffusion Facilitator）, Hup E/Ure J and CHR（chromate ion transporter） family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative Cop A/Cue O system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while Znt A transporter, assisted with putative Czc D, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid（IAA） secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.

Biochar-Bacillus consortium for a sustainable agriculture:physicochemical and soil stability analyses

Biochar has various agricultural applications,including the promising use as a carrier for beneficial microorganisms.However,most recent research has demonstrated the possible attachment or immobilization of a single bacterial species onto biochar rather than a consortium of microbes for biotechnological applications.Thus,an assessment on the potential of oil palm kernel shell(OPKS)biochar as a biofilm-producing Bacillus consortium carrier through optimization study on the operating and environmental factors influencing the biofilm adhesion was conducted using response surface methodology(RSM)and the subsequent soil stability and storage potential of the formulation.The highest Bacillus population was observed at temperature 33°C,agitation speed of 135 rpm,at a neutral pH of 7.5 with 10%(w/w)of sago starch as the co-carbon source.The adhesion of Bacillus on OPKS biochar following the optimized conditions fitted pseudo-second order(PSO)of kinetic modelling(R^(2)=0.998).The optimized formulation was subjected to storage in different temperatures and in vitro soil incubation which revealed that the Bacillus biofilmadhered OPKS biochar may be stored up to 4 months with minimum range of live Bacillus viability reaching 107 CFU g^(-1) of biochar which is within the minimum range of acceptable biofertilizer viability(10^(6) CFU mL^(-1)).Formulation that is viable in room storage can be easily incorporated into current agricultural distribution networks that do not have refrigeration.This work highlighted the physicochemical and soil stability qualities of optimized Bacillus consortium adhesion on biochar for agricultural usage.