fermentation Review Recent Advancements in Biological Conversion of Industrial Hemp for Biofuel and Value-Added Products Anqi Ji † , Linjing Jia † , Deepak Kumar * and Chang Geun Yoo *   Citation: Ji, A.; Jia, L.; Kumar, D.; Yoo, C.G. Recent Advancements in Biological Conversion of Industrial Hemp for Biofuel and Value-Added Products. Fermentation 2021, 7, 6. https://doi.org/10.3390/ fermentation7010006 Received: 15 December 2020 Accepted: 29 December 2020 Published: 5 January 2021 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Department of Chemical Engineering, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA; aji102@syr.edu (A.J.); ljia05@syr.edu (L.J.) * Correspondence: dkumar02@esf.edu (D.K.); cyoo05@esf.edu (C.G.Y.); Tel.: +1-315-470-6503 (D.K.); +1-315-470-6516 (C.G.Y.) † These authors contributed equally. Abstract: Sustainable, economically feasible, and green resources for energy and chemical products have people’s attention due to global energy demand and environmental issues. Last several decades, diverse lignocellulosic biomass has been studied for the production of biofuels and biochemicals. Industrial hemp has great market potential with its versatile applications. With the increase of the hemp-related markets with hemp seed, hemp oil, and fiber, the importance of hemp biomass utilization has also been emphasized in recent studies. Biological conversions of industrial hemp into bioethanol and other biochemicals have been introduced to address the aforementioned energy and environmental challenges. Its high cellulose content and the increased production because of the demand for cannabidiol oil and hempseed products make it a promising future bioenergy and biochemical source. Effective valorization of the underutilized hemp biomass can also improve the cost-competitiveness of hemp products. This manuscript reviews recent biological conversion strategies for industrial hemp and its characteristics. Current understanding of the industrial hemp properties and applied conversion technologies are briefly summarized. In addition, challenges and future perspectives of the biological conversion with industrial hemp are discussed. Keywords: industrial hemp; bioproducts; fermentation 1. Introduction Hemp is a type of the Cannabis sativa plant and has multiple applications in food, construction, pharmaceuticals, and materials like textile and paper (Figure 1)[1]. Whole hempseed can be used as food after dehulling and also produce hempseed oil and meal by cold-pressing [2–4]. Hemp flowers are used for the production of cannabidiol (CBD) and Δ-9-tetrahydrocannabinol (THC) [5,6], and roots can be used for phytoremediation [7]. The stem of hemp is composed of fiber and shiv and covered by bark [8]. The fiber and shiv have been used for paper and textile products and in the applications of animal bedding and construction materials, respectively [9–11]; however, the development of its applications in biofuels and biochemical applications were also studied due to its high carbohydrate contents [12,13]. Hemp has a long association with human life. It was used in fabrics, twine, and paper products in the 1800s and 1900s; however, its production and applications were regulated with the Marijuana Tax Act in 1937 and the Controlled Substances Act in 1970 by the US Congress [14]. In the 2014 Farm Bill, the US Congress defined industrial hemp depending on the level of THC (less than 0.3% THC on a dry weight basis) and allowed its agricultural pilot program by research institution and department of agriculture if the state laws allow [15]. The network map with the keywords, “hemp” and “industrial hemp,” in scientific articles from 2014 to 2020 was generated by VOSViewer with the full-counting method as presented in Figure 2. As shown in Figure 2a, overall hemp studies have been mainly Fermentation 2021, 7, 6. https://doi.org/10.3390/fermentation7010006 https://www.mdpi.com/journal/fermentation