Abstract
Microorganisms that display unique biotechnological characteristics are usually selected for industrial applications. Bacillus cereus NWUAB01 was isolated from a mining soil and its heavy metal resistance was determined on Luria–Bertani agar. The biosurfactant production was determined by screening methods such as drop collapse, emulsification and surface tension measurement. The biosurfactant produced was evaluated for metal removal (100 mg/L of each metal) from contaminated soil. The genome of the organism was sequenced using Illumina Miseq platform. Strain NWUAB01 tolerated 200 mg/L of Cd and Cr, and was also tolerant to 1000 mg/L of Pb. The biosurfactant was characterised as a lipopeptide with a metal-complexing property. The biosurfactant had a surface tension of 39.5 mN/m with metal removal efficiency of 69%, 54% and 43% for Pb, Cd and Cr respectively. The genome revealed genes responsible for metal transport/resistance and biosynthetic gene clusters involved in the synthesis of various secondary metabolites. Putative genes for transport/resistance to cadmium, chromium, copper, arsenic, lead and zinc were present in the genome. Genes responsible for biopolymer synthesis were also present in the genome. This study highlights biosurfactant production and heavy metal removal of strain NWUAB01 that can be harnessed for biotechnological applications.
Highlights
Industrialisation and mining activities have continued to put an increasing burden on the environment as a result of metal p ollution[1]
Ninety-eight heavy metal resistant bacterial isolates were isolated from the soil samples collected and one of the isolates was identified as B. cereus NWUAB01
The amplicon sequence was compared with the 16S ribosomal ribonucleic acid (rRNA) gene sequences in the National Centre for Biotechnology Information (NCBI) database and it showed that strain NWUAB01 had 100% similarity with Bacillus cereus strain BS16 (MH021873), B. wiedmanni strain F23 (MF681995), B. thuringiensis strain FDB-6 (MH260380), Bacillus sp strain SP9 (MH191109) and 99% similarity with B. proteolticus strain SPB3 (MG280785) with E-value of 0.00
Summary
Industrialisation and mining activities have continued to put an increasing burden on the environment as a result of metal p ollution[1]. Conventional methods of heavy metal removal involve treatment with chelating agents, organic and inorganic acids, reverse osmosis, surfactants and water These techniques are often expensive and ineffective for low metal concentration removal[1,5]. These mechanisms include biosorption, biotransformation, bioaccumulation, and biomineralisation[10] These organisms secrete a range of metal-sequestering polymers that are employed in metal u ptake[11,12]. The use of microbial biopolymers to enhance metal removal effectiveness is emerging as a promising technique These polymers can survive different pH and temperature range[13]. Their metal-binding capability depends on the producing organism, functional groups on the biopolymer, metal affinity and specificity, temperature and p H13–15. There have been various reports in literature on the metal-complexing abilities of biosurfactants in removing heavy metals from polluted soil and Scientific Reports | (2020) 10:19660
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