Bioresource Technology Reports 15 (2021) 100706 Available online 28 April 2021 2589-014X/© 2021 Elsevier Ltd. All rights reserved. Utilization of agro-industrial waste for biosurfactant production under submerged fermentation and its synergistic application in biosorption of Pb 2+ Swati Rastogi * , Shweta Tiwari , Sheel Ratna , Rajesh Kumar Rhizosphere Biology Laboratory, Department of Environmental Microbiology, Babasaheb Bhimrao Ambedkar (A Central) University, Vidya Vihar Raebareli Road, Lucknow 226025, India A R T I C L E INFO Keywords: Biowastes Waste management Bioremediation Biosorption Mathematical modelling ABSTRACT The biosurfactant production process was optimized using raw orange peel extract (ST reduction = 33.04 dyne cm 1 ; biosurfactant yield = ~3.7 g L 1 ) and the extracted metabolite was characterized in terms of its nature, and class/family. To the best of our knowledge, a frst report utilizing biowaste as a sole carbon substrate for simultaneous biosurfactant production and Pb 2+ removal under submerged fermentation by Bacillus haynesii strain E1. The results depicted the extracted biosurfactant to be of lipopeptide nature belonging to surfactin family having 50 mg L 1 of CMC. The crude biosurfactant was found to be tensioactive at temperature 70 ◦ C, 6% salt concentration, and varying pH range. The biosurfactant-producing bacterium effectively remediated Pb 2+ (high MIC = 2200 mg L 1 ) with a maximum adsorption capacity of 196.08 mg g 1 . The biosorption mechanism followed Langmuir (R 2 = 0.9724) and Pseudo second-order adsorption kinetics (R 2 = 0.9996; 200 mg L 1 ). 1. Introduction Microorganisms secrete metabolites that are known to ameliorate environmental stress. Biosurfactants (BSs) are one such secondary metabolite that are produced on the microbial cell surface or are released extracellularly. These are considered amphiphilic molecules on account of both hydrophilic and hydrophobic moieties that confer the potential to reduce surface and interfacial tension between the surfaces (Banat et al., 2021). In recent years, BSs have gained popularity as bioremediating agents due to the characteristics that offer them an edge over synthetic surfactants. Such characteristics include stability towards harsh temperature, pH, and saline conditions. Also, they are biocom- patible; possess low toxicity, biodegradability, and specifcity (Rastogi and Kumar, 2020). It is still a challenge regarding large scale production of BSs from an economical point but the environmental damage caused by chemical surfactants makes BSs potential representatives for biore- mediation purposes. As per these benefts, BSs are promising candidates for many commercial applications. But, their production must be cost- effective and to resolve this issue, various authors have recommended the usage of renewable agro-industrial wastes (biowastes) such as fruit and vegetable peels, etc. (Kumar and Ngueagni, 2021; Ratna et al., 2021). Such lignocellulosic biowastes would render a cheaper source of carbon substrate and parameters such as pH, temperature, agitation rate, etc. that would impact its production. But limited literature is available on the usage of these biowastes for biosurfactant production. The implementation of such bio wastes could resolve issues of biowastes management and also foster biosurfactant production simultaneously. Various anthropogenic activities and natural weathering have resulted in heavy metal accumulation in the environment. Some of them are required as growth supplements in optimum dosages. These heavy metals, for instance, lead (Pb 2+ ) is released from paint, metal pipe fac- tories, batteries, mining, electroplating industries, etc. (Nassiri et al., 2021). They are persistent in nature, non-biodegradable, and confer toxicity to the different fora and fauna of the ecosystem (Rastogi et al., 2019). The chronic Pb 2+ exposure could lead to neurological, meta- morphosis, and developmental abnormalities in aquatic organisms while stunted growth, diminished photosynthetic rate, etc. in plants. Kidney failure, reduced fertility, cardiovascular disorders, etc. are some malicious consequences in humans (Kumar et al., 2020). Few studies have been conducted regarding accelerated BS production in the pres- ence of metal ions (Kiran et al., 2014). BSs are reported to remove heavy metal ions from the contaminated systems (Rastogi et al., 2021). BS mediated heavy metal remediation/ removal occurs via adsorption and precipitation reactions based on Le Chatelier’s principle. An adsorption * Corresponding author. E-mail address: sswatirrastogi73@gmail.com (S. Rastogi). Contents lists available at ScienceDirect Bioresource Technology Reports journal homepage: www.sciencedirect.com/journal/bioresource-technology-reports https://doi.org/10.1016/j.biteb.2021.100706 Received 29 March 2021; Received in revised form 16 April 2021; Accepted 19 April 2021