Sustainable enzymatic treatment of organic waste in a framework of circular economy.

Enzymatic treatment of food and vegetable waste (FVW) is an eco-friendly approach for producing industrially relevant value-added products. This review describes the sources, activities and potential applications of crucial enzymes in FVW valorization. The specific roles of amylase, cellulase, xylanase, ligninase, protease, pectinase, tannase, lipase and zymase enzymes were explained. The exhaustive list of value-added products that could be produced from FVW is presented. FVW valorization through enzymatic and whole-cell enzymatic valorization was compared. The note on global firms specialized in enzyme production reiterates the economic importance of enzymatic treatment. This review provides information on choosing an efficient enzymatic FVW treatment strategy, such as nanoenzyme and cross-linked based enzyme immobilization, to make the process viable, sustainable and cheaper. Finally, the importance of life cycle assessment of enzymatic valorization of FVW was impressed to prove this approach is a better option to shift from a linear to a circular economy.

Emerging innovations for sustainable production of bioethanol and other mercantile products from circular economy perspective.

Biogenic municipal solid waste (BMSW) and food waste (FW) with high energy density are ready to tap renewable resources for industrial scale ethanol refinery foreseen for establishing bio-based society. Circular economy has occupied limelight in the domain of renewable energy and sustainable chemicals production. The present review highlights the importance of BMSW/FW as newer feed reserves that can cater as parent molecules for an array of high-visibility industrial products along with bioethanol upon implementing a judicious closed-cascade mass-flow mechanism enabling ultimate feed and waste stream valorisation. Though these organics are attractive resources their true potential for energy production has not been quantified yet owing to their heterogeneous composition and associated technical challenges thus pushing waste refinery and industrial symbiosis concepts to backseat. To accelerate this industrial vision, the novel bioprocessing strategies for enhanced and low-cost production of bioethanol from BMSW/FW along with other commercially imperative product portfolio have been discussed.

Sequential and consolidated bioprocessing of biogenic municipal solid waste: A strategic pairing of thermophilic anaerobe and mesophilic microaerobe for ethanol production.

Feedstock availability and its pretreatment, high process economics and insufficient ethanol (HEt) titres necessitated the bioprocesses that are sustainable. The advanced consolidated bioprocessing (CBPSeq) strategy presently considered for improved HEt production involves, sequential coupling of CBP thermophile, Clostridium thermocellum ATCC-27405 with mesophilic microaerobe, Pichia stipitis NCIM-3498. Biogenic municipal solid waste (BMSW) pretreated with 0.5% NaOH (CSPBMSW) served as the sole carbon source. CBPSeq (23.99 g/L) fared better than CBP standalone (18.10 g/L) wherein 1.32-folds improvement in HEt titre was recorded. Considering insufficient xylanase titre in cellulosome complex of C. thermocellum, CBPSeq was performed employing exogenous xylanases (CBPSeqE) to improve xylan digestibility and HEt yield. CBPSeqE-II biosystem at pH 5 showed maximum HEt titre of 36.90 g/L which corresponds to yield of 0.26 g HEt/ g CSPBMSW. This study substantiates efficacy of CBPSeqE-II biosystem in sustainable bioethanol production from BMSW in a single reactor without laborious steps.

Deoiled algal biomass derived renewable sugars for bioethanol and biopolymer production in biorefinery framework.

The present study is designed to evaluate the potential of deoiled algal biomass (DAB) residue as an alternative resource for the production of bioethanol and biopolymers in a biorefinery approach. Hybrid pretreatment method resulted in higher sugar solubilization (0.590 g/g DAB) than the corresponding individual physicochemical (0.481 g/g DAB) and enzymatic methods (0.484 g/g DAB). Subsequent utilization of sugars from hybrid pretreatment for bioethanol using Saccharomyces cerevisiaeresulted in maximum bioethanol production at pH 5.5 (0.145 ±â€¯0.008 g/g DAB) followed by pH 5.0 (0.122 ±â€¯0.004 g/g DAB) and pH 6.0 (0.102 ±â€¯0.002 g/g DAB). The experiments for biopolymer (PHB: polyhydroxybutyrate) production resulted in 0.43 ±â€¯0.20 g PHB/g DCW. Extracted polymer on NMR and FT-IR analysis showed the presence of PHB. Exploration of DAB as an alternative renewable resource for multiple biobased products supports sustainability and also enables entirety use of DAB by addressing the DAB-residue allied disposal issues.

Single pot bioprocessing for ethanol production from biogenic municipal solid waste.

Burgeoning global energy demand and rapid diminution of fossil fuel reserves urged to seek for a sustainable energy source like bioethanol. Single pot bioprocessing (SPB) strategy employing in-house laccase, cellulase plus xylanase and amylase along with hexose and pentose sugar fermenting yeasts (Saccharomyces cerevisiae and Pichia stipitis) is designed in this study for ethanol production from biogenic municipal solid waste (BMSW). BMSW when subjected to simultaneous pretreatment and saccharification (SPS) resulted in 79.69% enzymatic digestibility and fared better compared to alkali pretreated counterparts (14.03%-51.10%). The maximum total sugar release in case of SPS was 146.9 g/L in 24 h. The maximum ethanol concentration of 5.24% (v/v) in 30 h was obtained from SPB of BMSW at 25% (w/v) solid loading. SPB for ethanol production from BMSW is an interesting and effective alternative to MSW going to landfill or incineration with an added perk of waste to wealth conversion.

Partially consolidated bioprocessing of mixed lignocellulosic feedstocks for ethanol production.

Rapid urbanization and industrialization have accelerated the energy demand which cannot be met by decreasing fossil fuels thereby substantiate the need for lignocellulosic ethanol. The present study is one such attempt towards bioethanol production in an eco-friendly manner using enzymes in which a mixture of lignocellulosic biomass namely, Ricinus communis, Saccharum officinarum (tops) and Saccharum spontaneum were taken as a substrate. The mixed biomass was processed through partially consolidated bioprocessing (PCBP) approach which involves a non-isothermal simultaneous pretreatment and saccharification step where a concoction of laccase (Pleurotus djamor) and holocellulase (Trichoderma reseei RUT C30) was used followed by co-fermentation within the same reactor. The process parameters influencing PCBP were optimized using feed-forward ANN model which resulted in a maximum ethanol concentration of 7.86% (v/v) (62.01g/L) at pentose to hexose strain ratio of 0.696 (v/v), substrate loading of 27.54% (w/v) and incubation time of 21.96h.

Microbial synthesis of poly-3-hydroxybutyrate and its application as targeted drug delivery vehicle.

Arsenic trioxide loaded biocompatible PHB-PVA(1) nanoparticles (<100 nm in size) with folate functionalized surface were synthesized using poly-[(R)-3-hydroxybutyric acid] (PHB) produced by Bacillus firmus NII 0830. Folate functionalization was carried using dicyclohexyl carbodiimide (DCC) as a catalyst and 10-bromodecanol as a linker to conjugate glutamic acid terminal of folate with the hydroxylate groups present on the surface of PHBA-PVA(2) nanotrojans. The effect of fabrication parameters on shape, size distribution and PDI of the PHB nanoparticles were also investigated. It was observed that increase in sonication time and polyvinyl alcohol (PVA) concentration greatly reduced the size of nanoparticles. The drug release studies on arsenic trioxide incorporated PHB-PVA nanoparticles were conducted at physiological pH and temperature. FOL-PHBA-PVA(3) nanoparticles showed greater extent of cytotoxicity towards murine fibrosarcoma L929 cells than PHBA-PVA nanoparticles alone without conjugated folate, indicating the significance of folate as ligand for specific targeting of FR+ cancer cells.