## 1 Introduction  
Surfactants are amphiphilic organic compounds containing hydrophobic (water insoluble or oil soluble) and hydrophilic (water soluble) groups. This unique composition imparts them with excellent emulsifying/dispersion capabilities, which makes them very useful in food emulsifiers, detergents, paints, and agricultural sprays (herbicides) and in the dispersion of crude oil spills. The global surfactant market was valued at USD 41.3 billion in 2019 and was projected to reach USD 58 billion with a compounded annual growth rate (CAGR) of 5.3% between 2020 and 2027 [1]. While synthetic surfactants from petroleum-based intermediates are relatively cheaper, they ultimately will become unsustainable [2]. Surfactants produced using biological feedstock, either via growing microorganisms on them or via enzyme esterification reactions, are bio-based surfactants and will be favored for their lower environmental and health risks, biodegradability, and lower toxicity [3], if they are economically viable. Although process optimization via the manipulation of growth media and fermentation process factors is possible, it is critical to evaluate specific carbohydrate feedstocks and their process economics. The utilization of agricultural resources for bacterial fermentation to produce biosurfactants, such as surfactant and rhamn, through better pretreatment schemes, media manipulation, and enhancers use is expected to enhance the economic value of these resources [3]. Rhamolipids are one of the most studied bio-based surfactants produced through bacterial expression [4]. These are glycolipids consisting of a rhamne unit attached to a 3-(hydroxyalkanoyloxy) alkanoic acid (HAA) fatty acid tail (Figure 1), majorly produced through bacterial fermentation by Gram-negative _Pseudomonas_ species [5]. Rhamolipids have many applications across industries. These applications include (a) biomedical applications such as antimicrobial and antiviral agents, periodontal applications, ulcer treatments [6]; (b) environmental applications such as biodegradation agents, heavy metal absorption agents, disinfection agents, and cleaning formulation agents [7; 8; 9]; and (c) cosmetics and pharmaceutical applications such as shampoo formulation agents and ingredients in radiation and burn treatment formulations [10]. Rhamolipids are the secondary metabolites of aerobic bacterial expression; they require carefully designed growth media formulations and culture process controls to ensure maximum product generation and efficient product recovery through sterile purification procedures. Reported rhamnpid titers by different _Pseudomonas aeruginosa_ strains have ranged from 0.5 g/L to 78 g/L depending on the amount of carbohydrate added to the media, the inoculation volume, the type of culture and fermentation, i.e., batch or fed-batch, with yields (Y\({}_{\text{P/S}}\)) ranging between 0.058 and 0.62 (rhammolipid g/substrate g) [11]. Rhamolipids have been produced on various renewable substrates/carbohydrate sources, including olive oil, waste frying oil, waste fatty acids, corn oil, soybean oil, molasses, and spent wash from distillery waste [12]. One of the most studied substrates for rhamnids and biosurfactants in general is biomass sugars extracted through the pretreatment and enzymatic hydrolysis of cellulose and lignocellulosic biomass sources. One of  
Figure 1: The structure of di-rhammolipid with two rhamne units attached to a fatty acid chain, constituting the surfactant molecule’s complete structure [6]. the aims of this study is to understand the impact of such biomass-extracted carbohydrate substrate (soy hulls) on rhamnpid-generating bacterial growth performance and titers. The extraction of fermentable sugars from crude biomass sources' enzymatic hydrolysis leads to the challenge of complexity due to composite sugar mixtures in crude biomass sugar hydrolysates and because of how microbes utilize the various hexose, pentose, and other oligosaccharides in the media.