Culturable Heavy Metal-Resistant and Plant Growth Promoting Bacteria in V-Ti Magnetite Mine Tailing Soil from Panzhihua, China

Abstract

To provide a basis for using indigenous bacteria for bioremediation of heavy metal contaminated soil, the heavy metal resistance and plant growth-promoting activity of 136 isolates from V-Ti magnetite mine tailing soil were systematically analyzed. Among the 13 identified bacterial genera, the most abundant genus was Bacillus (79 isolates) out of which 32 represented B. subtilis and 14 B. pumilus, followed by Rhizobium sp. (29 isolates) and Ochrobactrum intermedium (13 isolates). Altogether 93 isolates tolerated the highest concentration (1000 mg kg−1) of at least one of the six tested heavy metals. Five strains were tolerant against all the tested heavy metals, 71 strains tolerated 1,000 mg kg−1 cadmium whereas only one strain tolerated 1,000 mg kg−1 cobalt. Altogether 67% of the bacteria produced indoleacetic acid (IAA), a plant growth-promoting phytohormone. The concentration of IAA produced by 53 isolates was higher than 20 µg ml−1. In total 21% of the bacteria produced siderophore (5.50–167.67 µg ml−1) with two Bacillus sp. producing more than 100 µg ml−1. Eighteen isolates produced both IAA and siderophore. The results suggested that the indigenous bacteria in the soil have beneficial characteristics for remediating the contaminated mine tailing soil.

Remediation of Heavy Metal-Contaminated Agricultural Soils Using Microbes

“…The success of heavy metal-contaminated soils is dependent on the potential of the microbes to produce high biomass, metabolites and biological activities under metal stress conditions (Ali et al 2012 ;Pajuelo et al 2014 ;Zaidi et al 2006 ;AbouShanab et al 2008 ;Esringü et al 2014 ;Gullap et al 2014 ;Braud et al 2009 ;Cornu et al 2014 ;Chompoothawat et al 2010 ). There are several advantages associated with the use of microbes for the remediation of heavy metal-contaminated soils in comparison with chemical amendments because the microbial biomass, metabolites and biological activities are biocompatible in nature, and it is also possible to produce them under in situ conditions (Yu et al 2014 ;Mani et al 2015 ;Banni and Faituri 2013 ;Gaur and Adholeya 2004 ;He et al 2009 ;Juwarkar and Singh 2010 ;Mani and Kumar 2014 ;Wang et al 2014a ). In addition, these microbes are also capable of producing plant growth-promoting substances, that is, organic acids, siderophores, plant growth hormones, 1-aminocyclopropane-1-carboxylic (ACC) acid deaminase and antimicrobial compounds, which are involved in the plant growth improvement in metal-contaminated soils (Wang et al 2014a ;Dimkpa et al 2009 ;Glick et al 2007 ;Göhre and Paszkowski 2006 ;Hayat et al 2010 ;Khan et al 2009b ;Adediran et al 2015 ;Ahemad and Kibret 2014 ;Zaidi et al 2009 ;Burd et al 2000 ;Wani et al 2009 ).…”

EVALUATION OF IAA AND PHAs PRODUCTION BY CHROMIUM RESISTANT BACTERIAL ISOLATES

“…These waste material contains a wide array of toxic metal predominantly hexavalent chromium Cr(VI), which persists in the soil for many years (Samantaray & Mishra, 2012). Long term accumulation of Cr(VI) in the soil decreases crop productivity in adjoining farming land and can effectively impact on the microbial diversity (Yu et al, 2014). As the conventional methods for treatment of Cr(VI) are not environmental friendly, thus it is imperative to look into economic and ecofriendly alternatives.…”

“…In addition to Cr(VI) detoxification, chromium resistant bacterial strains are also increasing nutrient availability of chromium contaminated soils (Pattnaik et al, 2017). In this regard, several studies have reported the utilization of plant growth-promoting bacteria (PGPB) that solubilize phosphate and synthesize growth-promoting substances such as indoleacetic acid (IAA) can be applied for bioremediation of metal-contaminated soil (Yu et al, 2014;Pattnaik et al, 2017;Patel et al, 2017).…”

“…Application of PGPB for Cr(VI) bioremediation not only increase NPK and IAA availability in chromium contaminated soil but also stimulate seed germination (Yu et al, 2014), seedling roots (Patten & Glick, 2002) and inhibition of phytopathogens (Haas & Défago, 2005). Additionally, utilization of PGPB strains with PHAs synthesizing ability for reclamation of chromium contaminated soil may be an added advantage.…”

Screening of Heavy Metal Tolerant Microbes in Sludge and Removal Capability of Lead

“…In recent years, due to the toxic action of heavy metal pollution is more and more harmful to environment and human health, research on the aspects of heavy metal pollution has drawn increasing attention in the research community, especially the field of bioremediation has become a hotspot [9][10][11][12]. As a new processing technology among different treatment techniques, bioremediation has a very broad development prospect in the aspect of wide application in treating wastewater treatment with heavy metal wastewater treatment of low concentration of heavy metal [13][14][15][16].…”