Production of bioethanol from sweet sorghum [Sorghum bicolor L] juice using yeast isolated from fermented sweet sorghum juice / Producción de bioetanol a partir de jugo de sorgo dulce [Sorghum bicolor L] utilizando levadura aislada de jugo de sorgo dulce fermentado

As a sugar-rich plant with no impact on global warming and food security, sweet sorghum can be exploited as an alternative source of renewable bioenergy. This study aimed to examine the potential of sweet sorghum juice for the generation of bioethanol using yeast isolated from the juice. The °Brix of sweet sorghum juice was measured using a digital refractometer. Additionally, 18 wild yeasts isolated from fermented sweet sorghum juice were subjected to various biochemical tests to describe them to identify potential yeast for ethanol production. The morphological and biochemical analyses of the yeasts revealed that all of the yeast isolates were most likely members of the genus Saccharomyces. The most ethanol-tolerant yeast isolate SJU14 was employed for sweet sorghum juice fermentation. A completely randomized factorial design was used with various fermentation parameters, primarily pH, temperature, and incubation period. Then ethanol content was determined using a potassium dichromate solution. According to the ANOVA, the highest ethanol content (18.765%) was produced at 30/26 °C, pH 4.5, and incubated for 96 h. Sweet sorghum juice was found to be an excellent source of potent yeasts, which have important industrial properties like the capacity to grow at high ethanol and glucose concentrations. Moreover, it can be utilized as a substitute substrate for the manufacturing of bioethanol production to lessen the environmental threat posed by fossil fuels. Further research is, therefore, recommended to develop strategically valuable applications of sweet sorghum for enhancing the food system and mitigating climate change.(AU)

Improvement of sorghum-wheat blended flours by E-beam irradiation: Physicochemical properties, rheological behavior, microstructure, and quality properties.

To enhance the processing suitability of blended flours, this study used 4 kGy E-beam irradiated (EBI) sorghum flour in different ratios blended with wheat flour and further verified the improvement mechanism of the processed products under the optimal ratios. The results suggested that the EBI can mitigate the deterioration of the blend flour farinograph properties while enhancing the gas release during dough fermentation. Under the same addition ratio, the irradiated blend flours showed higher expansion height, gas release, cavitation time, and gas retention coefficient than the control flours. Also, irradiated blend flours retained a gluten network at a higher addition rate (20 %). Moreover, the irradiated blend flours were optimized at 10 % as its pasting and thermal properties were improved. Notably, this ameliorating effect promotes a decrease in hardness and chewiness and an increase in cohesion of the bread cores, presenting better textural attributes and delaying the aging rate during storage. The findings are instructive for applying EBI technology in the manufacture and quality improvement of mixed grain breads and open a new research avenue for processing sorghum staple foods.

Bioaugmented ensiling of sweet sorghum with Pichia anomala and cellulase and improved enzymatic hydrolysis of silage via ball milling.

Sweet sorghum, as a seasonal energy crop, is rich in cellulose and hemicellulose that can be converted into biofuels. This work aims at investigating the effects of synergistic regulation of Pichia anomala and cellulase on ensiling quality and microbial community of sweet sorghum silages as a storage and pretreatment method. Furthermore, the combined pretreatment effects of ensiling and ball milling on sweet sorghum were evaluated by microstructure change and enzymatic hydrolysis. Based on membership function analysis, the combination of P. anomala and cellulase (PA + CE) significantly improved the silage quality by preserving organic components and promoting fermentation characteristics. The bioaugmented ensiling with PA + CE restructured the bacterial community by facilitating Lactobacillus and inhibiting undesired microorganisms by killer activity of P. anomala. The combined bioaugmented ensiling pretreatment with ball milling significantly increased the enzymatic hydrolysis efficiency (EHE) to 71%, accompanied by the increased specific surface area and decreased pore size/crystallinity of sweet sorghum. Moreover, the EHE after combined pretreatment was increased by 1.37 times compared with raw material. Hence, the combined pretreatment was demonstrated as a novel strategy to effectively enhance enzymatic hydrolysis of sweet sorghum.

Polyphenol recovery from sorghum bran waste by microwave assisted extraction: Structural transformations as affected by grain phenolic profile.

Sorghum milling waste stream (bran), contains diverse phenolic compounds with bioactive properties. The study determined the potential of microwave assisted extraction (MAE) to recover the bran phenolic compounds. Red, white, and lemon-yellow pericarp sorghum brans were subjected to MAE and phenolic yield and structural transformation vs conventional extraction (control) assessed by UPLC-MS/MS, Folin-Ciocalteu and Trolox equivalent antioxidant capacity methods. Phenols yield increased from 3.7-20.3 to 12.6-75.5 mg/g, while antioxidants capacity increased average 3.3X in MAE extracts vs controls. Hydroxycinnamic acids increased most dramatically (3.0-32X) in MAE extracts (0.08-2.64 to 2.57-8.01 mg/g), largely driven by release of cell-wall derived feruloyl- and coumaroyl-arabinose. MAE hydrolyzed flavonoid glycosides into aglycones, and depolymerized condensed flavonoid heteropolymers into flavanones, flavanols and (deoxy)anthocyanidins. Thus, MAE dramatically enhances yield of valuable phenolics from sorghum bran waste, but also alters the phenolic profile in ways that may influence their chemical and biological properties.

Impact of ultrasound treatment on the physicochemical and rheological properties of acid hydrolyzed sorghum starch.

The present study aimed to evaluate the influence of ultrasonication on the physicochemical properties of native and acid-hydrolyzed white sorghum starch. Sorghum starch exhibited improved freeze-thaw stability, solubility, swelling power, and paste clarity after mild sonication. Starches sonicated at 30 % amplitude for 10 and 20 min increased the peak viscosity to 249 and 240 BU, gel firmness to 140.23 and 131.62 (g), ΔH to 13.4 and 13.1 (J/g), crystallinity to 29.51 and 29.10 (%), double helix content to 1.11 and 1.07 and degree of ordered structures to 1.16 and 1.09. The sonicated dual-treated samples (sonicated-acid hydrolyzed) exhibited reduced swelling power, peak viscosity, gelatinization temperatures and gel firmness. In contrast, the solubility, paste clarity, ΔH, percentage of crystallinity, double helix content and degree of ordered structures improved. Ultrasonic treatment made cracks and holes in the granule surface, whereas dual-treated starches were more porous and rougher, with deep depressions. All sorghum starches displayed shear-thinning behavior (n < 1). The pseudoplastic behavior and consistency indices of the starch paste decreased with increasing sonication time and amplitude. The G' was always higher than G" and tanδ was <1 for all samples, indicating a more solid/elastic behavior. The increased sonication time and amplitude, as well as the dual-treatment, caused the gel to become more susceptible to shear forces, which resulted in a decrease in G' and G" and an increase in tanδ.

Investigating sorghum protein solubility and in vitro digestibility during seed germination.

In this work, we examined the impact of sorghum gain germination on kafirins solubility and digestibility. Two genotypes differing in their proteins and tannins contents were germinated under controlled conditions up to radicle emergence. Biochemical, physicochemical, and in vitro digestibility tests were applied on the germinated grains. Microscopic examination of grains endosperm revealed that germination resulted in pitted starch granules and protein matrix slackening. Apart cystine and the amount of free thiol groups which increased significantly, the overall amino acids composition remained rather unchanged, just as the kafirins solubility and size distribution. In contrast germination was demonstrated to improved significantly the in vitro protein digestibility, even after cooking and especially for the genotype poor in tannin. Without inducing major physicochemical changes, germination enhanced kafirins susceptibility to gastrointestinal proteases. Germination may be a way to improve the nutritional value of sorghum.

Passive permeability controls synthesis for the allelochemical sorgoleone in sorghum root exudate.

Competition for soil nutrients and water with other plants foster competition within the biosphere for access to these limited resources. The roots for the common grain sorghum produce multiple small molecules that are released via root exudates into the soil to compete with other plants. Sorgoleone is one such compound, which suppresses weed growth near sorghum by acting as a quinone analog and interferes with photosynthesis. Since sorghum also grows photosynthetically, and may be susceptible to sorgoleone action if present in tissues above ground, it is essential to exude sorgoleone efficiently. However, since the P450 enzymes that synthesize sorgoleone are intracellular, the release mechanism for sorgoleone remain unclear. In this study, we conducted an in silico assessment for sorgoleone and its precursors to passively permeate biological membranes. To facilitate accurate simulation, CHARMM parameters were newly optimized for sorgoleone and its precursors. These parameters were used to conduct 1 µs of unbiased molecular dynamics simulations to compare the permeability of sorgoleone with its precursors molecules. We find that interleaflet transfer is maximized for sorgoleone, suggesting that the precursor molecules may remain in the same leaflet for access by biosynthetic P450 enzymes. Since no sorgoleone was extracted during unbiased simulations, we compute a permeability coefficient using the inhomogeneous solubility diffusion model. The requisite free energy and diffusivity profiles for sorgoleone through a sorghum membrane model were determined through Replica Exchange Umbrella Sampling (REUS) simulations. The REUS calculations highlight that any soluble sorgoleone would quickly insert into a lipid bilayer, and would readily transit. When sorgoleone forms aggregates in root exudate as indicated by our equilibrium simulations, aggregate formation would lower the effective concentration in aqueous solution, creating a concentration gradient that would facilitate passive transport. This suggests that sorgoleone synthesis occurs within sorghum root cells and that sorgoleone is exuded by permeating through the cell membrane without the need for a transport protein once the extracellular sorgoleone aggregate is formed.

Dry heat whole Sorghum BRS 305 flour modulate satiety and improves antioxidant response in brain of Wistar rats fed with high-fat high-fructose diet.

Sorghum BRS 305 (Sorghum bicolor L. Moench) is a cereal with high tannins and anthocyanins content and keep better the resistant starch when submitted to dry heat treatment. Our objective was to investigate the effects of BRS 305 dry heat treatment whole sorghum flour on satiety and antioxidant response in brain and adipose tissue of Wistar rats fed with a high fat high fructose diet (HFHF). Male Wistar rats were divided in two groups: control (n = 8) and HFHF (n = 16) for eight weeks. After, animals of HFHF group were divided: HFHF (n = 8) and HFHF + BRS 305 sorghum whole flour (n = 8), for 10 weeks. Sorghum consumption reduced gene expression of leptin, resistin, and endocannabinoid receptor 1 type (CB1) in adipose and brain tissues compared to HFHF group. In brain, sorghum consumption also promotes reduction in neuropeptide Y (NPY) gene expression. BRS305 sorghum consumption improved gene expression of sirtuin-1 (SIRT1) in adipose tissue, and in the brain increased heat shock protein 72 (HSP72), erythroid-derived nuclear factor 2 (NRF2), peroxisome proliferator-activated receptor alpha (PPARα), superoxide dismutase (SOD) and catalase activity compared to HFHF. In silicoanalysis showed interaction with PPARα, CB1, and leptin receptors. Advanced glycation end products (AGEs) concentrations in group HFHF + sorghum did not differ from HFHF group. Advanced glycation end products receptors (RAGEs) concentrations did not differ among experimental groups. Then, BRS 305 sorghum submitted to dry treatment was able to modulate gene expression of markers related to satiety and improve antioxidant capacity of rats fed with HFHF diet.

Comprehensive evaluation of nutritional components, bioactive metabolites, and antioxidant activities in diverse sorghum (Sorghum bicolor (L.) Moench) landraces.

Sorghum, one of the prospective crops for addressing future food and nutrition security, has received attention in recent years due to its health-promoting compounds. It is known that several environmental and genetic factors affect the metabolite contents of dietary crops. This study investigated the diversity of different nutrients, functional metabolites, and antioxidant activity using three different assays in 53 sorghum landraces from Korea, China, Japan, Ethiopia, and South Africa. The effects of origin and seed color variations were also investigated. Total phenolic (TPC), total tannin (TTC), total fat, total protein, total dietary fiber, and total crude fiber contents all varied significantly among the sorghum landraces (p < 0.05). Using a gas chromatography-flame ionization detector, palmitic, stearic, oleic, linoleic, and linolenic acids were detected in all the sorghum landraces, and their content significantly varied (p < 0.05). Furthermore, four 3-deoxyanthocyanidins (luteolinidin, apigeninidin, 5-methoxyluteolinidin, and 7-methoxyapigeninidin) and two flavonoids (luteolin and apigenin) were detected in most of the landraces using liquid chromatography-tandem mass spectrometry, and their concentrations also significantly varied. Statistical analyses supported by multivariate tools demonstrated that seed color variation had a significant effect on TPC, TTC, DPPH• and ABTS•+ scavenging activities, and ferric-reducing antioxidant power, with yellow landraces having the highest and white landraces having the lowest values. Seed color variation also had a significant effect on dietary fiber, linoleic acid, linolenic acid, and luteolin contents. In contrast, all nutritional components and fatty acids except total protein and oleic acid were significantly affected by origin, while most 3-deoxyanthocyanidins and flavonoids were unaffected by both origin and seed color differences. This is the first study to report the effect of origin on sorghum seed metabolites and antioxidant activities, laying the groundwork for future studies. Moreover, this study identified superior landraces that could be good sources of health-promoting metabolites.

The waxy mutation in sorghum and other cereal grains reshapes the gut microbiome by reducing levels of multiple beneficial species.

Waxy starches from cereal grains contain >90% amylopectin due to naturally occurring mutations that block amylose biosynthesis. Waxy starches have unique organoleptic characteristics (e.g. sticky rice) as well as desirable physicochemical properties for food processing. Using isogenic pairs of wild type sorghum lines and their waxy derivatives, we studied the effects of waxy starches in the whole grain context on the human gut microbiome. In vitro fermentations with human stool microbiomes show that beneficial taxonomic and metabolic signatures driven by grain from wild type parental lines are lost in fermentations of grain from the waxy derivatives and the beneficial signatures can be restored by addition of resistant starch. These undesirable effects are conserved in fermentations of waxy maize, wheat, rice and millet. We also demonstrate that humanized gnotobiotic mice fed low fiber diets supplemented with 20% grain from isogenic pairs of waxy vs. wild type parental sorghum have significant differences in microbiome composition and show increased weight gain. We conclude that the benefits of waxy starches on food functionality can have unintended tradeoff effects on the gut microbiome and host physiology that could be particularly relevant in human populations consuming large amounts of waxy grains.

Trait stacking simultaneously enhances provitamin A carotenoid and mineral bioaccessibility in biofortified Sorghum bicolor.

Vitamin A, iron, and zinc deficiencies are major nutritional inadequacies in sub-Saharan Africa and disproportionately affect women and children. Biotechnology strategies have been tested to individually improve provitamin A carotenoid or mineral content and/or bioaccessibility in staple crops including sorghum (Sorghum bicolor). However, concurrent carotenoid and mineral enhancement has not been thoroughly assessed and antagonism between these chemical classes has been reported. This work evaluated two genetically engineered constructs containing a suite of heterologous genes to increase carotenoid stability and pathway flux, as well as phytase to catabolize phytate and increase mineral bioaccessibility. Model porridges made from transgenic events were evaluated for carotenoid and mineral content as well as bioaccessibility. Transgenic events produced markedly higher amounts of carotenoids (26.4 µg g-1 DW) compared to null segregants (4.2 µg g-1 DW) and wild-type control (Tx430; 3.7 µg g-1 DW). Phytase activation by pre-steeping flour resulted in significant phytate reduction (9.4 to 4.2 mg g-1 DW), altered the profile of inositol phosphate catabolites, and reduced molar ratios of phytate to iron (16.0 to 4.1), and zinc (19.0 to 4.9) in engineered material, suggesting improved mineral bioaccessibility. Improved phytate : mineral ratios did not significantly affect micellarization and bioaccessible provitamin A carotenoids were over 23 times greater in transgenic events compared to corresponding null segregants and wild-type controls. A 200 g serving of porridge made with these transgenic events provide an estimated 53.7% of a 4-8-year-old child's vitamin A estimated average requirement. These data suggest that combinatorial approaches to enhance micronutrient content and bioaccessibility are feasible and warrant further assessment in human studies.

Optimization of energy recovery efficiency from sweet sorghum stems by ethanol and methane fermentation processes coupling.

Taken separately, a single sweet sorghum stem bioconversion process for bioethanol and biomethane production only leads to a partial conversion of organic matter. The direct fermentation of crushed whole stem coupled with the methanization of the subsequent solid residues in a two-stage process was experimented to improve energy bioconversion yield, efficiency, and profitability. The raw stalk calorific value was 17,144.17 kJ/kg DM. Fermentation step performed using Saccharomyces cerevisiae resulted in a bioconversion yield of 261.18 g Eth/kg DM, i.e. an energy recovery efficiency of 6921.27 kJ/kg DM. The methanogenic potentials were 279 and 256 LCH4/kg DM, respectively, for raw stem and fermentation residues, i.e. energy yields of 10,013.31 and 9187.84 kJ/kg DM, respectively. Coupling processes have significantly increased yield and made it possible to reach 13,309.57 kJ/kg DM, i.e. 77.63% of raw stem energy recovery yield, compared to 40.37% and 58.40%, respectively, for single fermentation and methanization processes.

Sweet sorghum stem is a viable feedstock source for efficient coproduction of ethanol and methaneSorghum stems calorific value determination revealed an energy potential of 17.15 MJ/kg DMEnergy recovery by single methanization yielded 18.03% more than ethanol fermentationCoupling processes has significantly increased energy recovery yield and profitability.

Effect of extrusion processing on techno-functional properties, textural properties, antioxidant activities, in vitro nutrient digestibility and glycemic index of sorghum-chickpea-based extruded snacks.

Physico-chemical, textural, functional, and nutritional properties of the twin screw extruded whole sorghum-chickpea (8:2) snacks was investigated using in vitro procedures. The extruded snacks were analyzed for the effect of variations in extruded conditions on their properties: barrel BT (BT) (130-170°C) and feed moisture (FM) (14%-18%), keeping screw speed constant (400 rpm). The results revealed that specific mechanical energy (SME) decreased (74.4-60.0) in response to rise in both BT and FM, whereas expansion ratio (ER) had shown an alternative relation as it decreased with elevated FM (2.17 at 14%, 130°C to 2.14 at 16%, 130°C) and increased with BT (1.75 at 18%, 130°C to 2.48 at 18%, 170°C). The values of WAI and WSI improved with the surge in BT, which was associated with enhanced disruption of starch granules at higher BT. Raise in FM incremented the total phenolic content (TPC) and hence the antioxidant activity (AA) (FRAP and DPPH) along with the hardness of snacks. As per in vitro starch digestibility is concerned, slowly digestible starch (SDS) content as well as glycemic index (51-53) of the extrudates depressed with increasing BT and FM. Also, lower BT and FM improved the functional properties such as expansion ratio, in-vitro protein digestibility, and overall acceptability of the snacks. A positive correlation was seen among SME and hardness of the snacks, WSI and ER, TPC and AA, SDS and Exp-GI, color and OA, texture and OA.

Sorghum grain germination as a route to improve kafirin digestibility: Biochemical and label free proteomics insights.

Kafirin, the sorghum grain storage protein presents lower digestibility compared to its cereals counterparts. Germination has been proposed as an adequate bioprocessing method to improve seed protein digestibility. Here, germination was rationalized so as to evenly sample germinated seeds and the dynamic changes of the proteome and several biochemical markers was connected for the first time with the in vitro protein digestibility of germinated seeds. Free sulfhydryl groups increased during germination and in vitro protein digestibility enhanced. The dynamic in abundance of several enzymes out of which 3 cysteine proteases were found to coincide with appearance of aqueous soluble peptides derived from kafirin at boot time of their degradation. The study provides deep information about the molecular events occurring during sorghum seed germination and reveals potential biomarkers of the kafirin proteolysis. It points a way to improve sorghum nutritional value through controlled germination.

Structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm: A review.

This review focuses on the structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm. Sorghum is an important cereal crop that is well suited to grow in regions with high temperatures and limited water resources due to its C4 metabolism. The endosperm of sorghum kernels is a rich source of starch, which is composed of two main components: amylose and amylopectin. The synthesis of starch in sorghum endosperm involves multiple enzymatic reactions, which are regulated by complex genetic and environmental factors. Recent research has identified several genes involved in the regulation of starch synthesis in sorghum endosperm. In addition, the structure and properties of sorghum starch can also be influenced by environmental factors such as temperature, water availability, and soil nutrients. A better understanding of the structure and genetic regulation of starch formation in sorghum endosperm can have important implications for the development of sorghum-based products with improved quality and nutritional value. This review provides a comprehensive summary of the current knowledge on the structure and genetic regulation of starch formation in sorghum endosperm and highlights the potential for future research to further improve our understanding of this important process.

Mycological and Multiple Mycotoxin Surveillance of Sorghum and Pearl Millet Produced by Smallholder Farmers in Namibia.

Mycological (mycotoxigenic Fusarium and aflatoxigenic Aspergillus spp.) and multiple mycotoxins [aflatoxin B1 (AFB1), fumonisin B (FB), deoxynivalenol and zearalenone] surveillance was conducted on raw whole grain sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) produced on smallholder farms, and processed products sold at open markets in northern Namibia. Fungal contamination was determined with morphological methods as well as with quantitative Real-Time PCR (qPCR). The concentrations of multiple mycotoxins in samples were determined with liquid chromatography tandem mass spectrometry. The incidence of mycotoxigenic Fusarium spp., Aspergillus flavus and A. parasiticus, as well as the concentrations of AFB1 and FB were significantly (P < 0.001) higher in the malts as compared to the raw whole grains, with Aspergillus spp. and AFB1 exhibiting the highest contamination (P < 0.001). None of the analysed mycotoxins were detected in the raw whole grains. Aflatoxin B1 above the regulatory maximum level set by the European Commission was detected in sorghum (2 of 10 samples; 20%; 3-11 µg/kg) and pearl millet (6 of 11 samples; 55%; 4-14 µg/kg) malts. Low levels of FB1 (6 of 10 samples; 60%; 15-245 µg/kg) were detected in sorghum malts and no FB was detected in pearl millet malts. Contamination possibly occurred postharvest, during storage, and/or transportation and processing. By critically monitoring the complete production process, the sources of contamination and critical control points could be identified and managed. Mycotoxin awareness and sustainable education will contribute to reducing mycotoxin contamination. This could ultimately contribute to food safety and security in northern Namibia where communities are exposed to carcinogenic mycotoxins in their staple diet.

In vivo cadmium-assisted dilute acid pretreatment of the phytoremediation sweet sorghum for enzymatic hydrolysis and cadmium enrichment.

Phytoremediation with energy crops is considered an integrated technology that provides both environment and energy benefits. Herein, the sweet sorghum cultivated on Cd-contaminated farmland (1.21 mg/kg of Cd in the soil) showed promising phytoremediation potential, and the approach for utilizing sorghum stalks was explored. Sweet sorghum bagasse with Cd contamination was pretreated with dilute acid in order to improve enzymatic saccharification and achieve Cd recovery, resulting in harmless and value-added utilization. After pretreatment, hemicelluloses were dramatically degraded, and the lignocellulosic structures were partially deconstructed with xylan removal up to 98.1%. Under the optimal condition (0.75% H2SO4), the highest total sugar yield was 0.48 g/g of raw bagasse; and nearly 98% of Cd was enriched in the liquid phase. Compared with normal biomass, Cd reduced the biomass recalcitrance and further facilitated the deconstruction of biomass under super dilute acid conditions. This work provided an example for the subsequent valorization of Cd-containing biomass and Cd recovery, which will greatly facilitate the development of phytoremediation of heavy metal contaminated soil.

Modification of sorghum starch as a function of pullulanase hydrolysis and infrared treatment.

Papain-pretreated sorghum grains were modified by using pullulanase and infrared (IR) irradiation to decrease starch digestibility. An optimum synergistic effect was found under conditions of pullulanase (1 U/ml/5h) and IR (220 oC/3 min) treatment, which produced modified corneous endosperm starch with 0.022 hydrolysis rate, 42.58 hydrolysis index, and 0.468 potential digestibility. The modification increased amylose content and crystallinity up to 31.31 % and 62.66 %, respectively. However, the starch modification decreased its swelling power, solubility index, and pasting properties. FTIR revealed an increase in the ratio of 1047/1022 and a decrease in 1022/995, indicating the formation of a more orderly structure. The debranching effect of pullulanase was stabilized by the IR radiation amplifying its effect on starch digestibility. Therefore, the combination of debranching and infrared treatment could be an efficient method to produce 'tailor-made' starch, that can be further utilized in food industries to manufacture food for target population.

Enhancement of Biomass Conservation and Bioethanol Production of Sweet Sorghum Silage by Constructing Synergistic Microbial Consortia.

The efficient storage of materials before bioethanol production could be key to improving pretreatment protocol and facilitating biodegradation, in turn improving the cost-effectiveness of biomass utilization. Biological inoculants were investigated for their effects on ensiling performance, biodegradability of silage materials, and final bioethanol yield from sweet sorghum. Two cellulolytic microbial consortia (CF and PY) were used to inoculate silages of sweet sorghum, with and without combined lactic acid bacteria (Xa), for up to 60 days of ensiling. We found that the consortia notably decreased pH and ammonia nitrogen content while increasing lactic acid/acetic acid ratios. The microbes also functioned in synergy with Xa, significantly reducing lignocellulose content and improving biomass preservation. First-order exponential decay models captured the kinetics of nonstructural carbohydrates and suggested high water-soluble carbohydrate (grams per kilogram dry matter [DM]) preservation potential in PY-Xa (33.48), followed by CF-Xa (30.51). Combined addition efficiently improved enzymatic hydrolysis and enhanced bioethanol yield, and sweet sorghum treated with PY-Xa had the highest ethanol yield (28.42 g L-1). Thus, combined bioaugmentation of synergistic microbes provides an effective method of improving biomass preservation and bioethanol production from sweet sorghum silages. IMPORTANCE Ensiling is an effective storage approach to ensure stable year-round supply for downstream biofuel production; it offers combined facilities of storage and pretreatment. There are challenges in ensiling sweet sorghum due to its coarse structure and high fiber content. This study provides a meaningful evaluation of the effects of adding microbial consortia, with and without lactic acid bacteria, on changes in key properties of sweet sorghum. This study highlighted the bioaugmented ensiling using cellulolytic synergistic microbes to outline a cost-effective strategy to store and pretreat sweet sorghum for bioethanol production.

Determination of standardised ileal digestibility of amino acids in high-fibre feedstuffs and additivity of apparent and standardised ileal amino acids digestibility of diets containing mixtures of maize, sorghum, and soybean meal.

1. Two experiments were conducted to determine the coefficients of standardised ileal amino acid digestibility for selected high-fibre feedstuffs (Expt.1) and to assess the additivity of coefficients of apparent (cAIAAD) and standardised (cSIAAD) ileal amino acid digestibility for diets containing combinations of sorghum, maize and soybean meal.2. In Expt. 1, broiler chickens (324) were allocated to 54 metabolism cages (nine diets with six replicates). In Expt. 2, broiler chickens (315) were allocated to 63 metabolism cages (seven diets with nine replicates). The diets in Expt. 1 were a nitrogen-free diet plus eight semi-purified diets in which soybean meal (SBM), low-protein SBM (LPSBM), soybean hull, wheat bran, maize bran, rice bran, dried sugarbeet pulp or maize gluten feed were the only sources of protein in the respective diets. In Expt. 2, the seven diets were a nitrogen-free diet, and six semi-purified diets consisting of individual feedstuffs (SBM, maize, or sorghum) or combinations (maize and SBM; sorghum and SBM; or maize, sorghum, and SBM) as the only sources of protein.3. In both experiments, all the broiler chickens received the same maize-SBM diet formulated to meet nutrient requirements according to the breeder's recommendations from d 0 to 16. Allocated experimental diets were provided on d 16, and ileal digesta were collected on d 21.4. In Expt. 1, SBM and LPSBM had greater (P < 0.01) cSIAAD for indispensable and dispensable amino acids than the other feedstuffs. The rice bran had greater (P<0.01) cSIAAD values than wheat bran and maize bran, except for Leu, Cys, and Pro.5. In Expt. 2, predicted cAIAAD values for maize-SBM and maize-sorghum-SBM were generally lower (P<0.01) than actual values. The actual and predicted cSIAAD values for maize-SBM, sorghum-SBM and maize-sorghum-SBM combinations were not significantly different.6. It was concluded that the standardised amino acid digestibility of sorghum, when combined with other feedstuffs, was additive and that approximately three-quarters of total amino acids in the assayed high-fibre feedstuffs, except for dried sugarbeet pulp and maize gluten feed, were digestible.