Sweet Sorghum Research Articles

Early-Generation Evaluation of Marker-Assisted Transfer of bmr6 and bmr12 Alleles into Sweet and High-biomass Sorghum

The effects of transferring brown midrib (bmr) alleles in sweet and high biomass sorghums (SS/HBM) are not fully understood, and available works produced mixed results depending upon the genetic background of the recurrent parent used. Early-generation testing of the effects of the two mutations in the background of the recurrent parents can help predict the final products and make appropriate early go/no-go breeding decisions, yet, this information is missing. The present study was therefore carried out to reduce these gaps. Marker-assisted transfer of the bmr6 and bmr12 was performed using four (SSV84, ICSB474, ICSV18003, ICSV100324) SS and one (ICSV15024) HBM wild type (WT) lines as recurrent parents, and one bmr6 (N609) and two bmr12 (ICSV101039 and N600) lines as donor parents. Crossing and backcrossing techniques were used to transfer the bmr alleles to develop BC2F2 and F3 populations. Kompetitive allele-specific PCR (KASP) marker genotyping assays were performed and implemented for the indirect selection of the bmr transfer in F1 and BC_F1 populations. While the bmr6 markers were polymorphic, the bmr12 markers were monomorphic. The successful bmr6 transfer was therefore confirmed by markers in F1 and BC_F1, while for bmr12 the transfer was confirmed after segregation assessment in F2 and BC_F2 populations. The transfer of bmr12 improved the cellulose content relative to WT genotypes, and bmr12 populations were shorter-statured relative to bmr6 individuals, meaning that bmr12 gene can be considered in sorghum breeding to boost 2G bioethanol bioconversion and to control lodging, and hence favouring mechanical harvesting and limiting yield losses. The observed earliness in the bmr lines is an attractive trait conferring adaptation in the drylands, particularly in the world’s semi-arid tropics characterized by terminal drought stress. Both bmr alleles did not show any negative trade-offs relative to the must-have sorghum plant characteristics, implying that they can safely be deployed in sorghum breeding for bioenergy production purposes. The observed superior bmr lines with farmer-preferred phenotypic acceptance are candidates not only for advancement in breeding pipelines but also for subsequent pyramiding bmr6 and bmr12 in the same genetic background, further improving the bmr-conferred benefits. The successfully used molecular markers will be uploaded in the public domain and can help breed sorghum products other than SS/HBM such as high-quality forage sorghums.

Production of Sweet and High Biomass Sorghum Lines with Optimized Cell Wall Components for Increased Biofuel Bioconversion Yield

The current research focuses on the estimation of fibre content in sweet and high biomass sorghum lines for Production of sweet and high biomass sorghum lines with optimized cell wall components for increased biofuel bioconversion yield, through partially replicated experimental design for F3   populations based on BLUPs values; this study was carried out for four seasons (from postrainy 2020 to rainy 2022) to develop F3 populations of sweet and high-biomass bmr sorghum lines. The proximate fibre component analysis was done in the matured F3 populations by drying the plant samples and grinding them into a fine powder. Fibre quality components such as cellulose, hemicellulose, acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent fibre (NDF), metabolizable energy (ME), nitrogen, in vitro organic matter digestibility (IVOMD), and ash, were assessed using Near-Infrared Reflectance Spectroscopy (NIRS). ICSV18003 had the lowest acid detergent fibre (ADF) percentage at 37.04%, while it also had the highest acid detergent lignin (ADL) percentage at 3.84%. The ash percentage was 3.73% in SSV84 × N609. Moreover, the bmr transferred lines of the F3 population exhibited higher levels of cellulose and hemicellulose, while lignin and ash content were decreased. This indicates that the bmr6 and bmr12 alleles can be confidently utilized in sorghum breeding for bioenergy production, as they meet the requirements for bioethanol production.

Fuel properties and incineration behavior of poultry litter blended with sweet sorghum bagasse and pyrolysis oil

The incineration of poultry litter (PL) effectively reduces the volume of waste in line with the United Nations Sustainable Development Goal of “affordable and clean energy”. However, mono-incineration is associated with considerable challenges due to the varying moisture, structural and chemical composition and low energy yield. The aim of the present work was to investigate the influence of sweet sorghum bagasse (SS) and pyrolysis oil (PO) on improving the fuel properties of PL and mitigating ash related burdens during incineration. The different biomass feedstocks were produced by combining PL with SS at 0.0% (T0), 25% (T1), 50% (T2), 75% (T3) and compared with 100% SS (T4). In order to achieve high energy potential and low ash deposition, the parallel samples were additionally mixed with 10% PO to improve the energy value. The experimental results show that increasing the proportion of SS and adding PO to the mixtures increases the volatile matter and decreases the moisture and ash content. The addition of PO also increases the carbon and hydrogen content. The use of SS and PO thus increased the values of the ignitability index and apparently also the flammability by 30.0%–49.4% compared to pure PL. SS and PO shifted the HHV of the starting material from 16.90 to 18.78 MJ kg−1. In addition, SS + PO improved the flame volume and red color intensity of the PL blends based on the image analysis method. However, the presence of SS and PO did not sufficiently improve the ash-related index values, which requires further investigation.

Simulating short-term light responses of photosynthesis and water use efficiency in sweet sorghum under varying temperature and CO2 conditions.

Climate change, characterized by rising atmospheric CO2 levels and temperatures, poses significant challenges to global crop production. Sweet sorghum, a prominent C4 cereal extensively grown in arid areas, emerges as a promising candidate for sustainable bioenergy production. This study investigated the responses of photosynthesis and leaf-scale water use efficiency (WUE) to varying light intensity (I) in sweet sorghum under different temperature and CO2 conditions. Comparative analyses were conducted between the A n-I, g s-I, T r-I, WUEi-I, and WUEinst-I models proposed by Ye etal. and the widely utilized the non-rectangular hyperbolic (NRH) model for fitting light response curves. The Ye's models effectively replicated the light response curves of sweet sorghum, accurately capturing the diminishing intrinsic WUE (WUEi) and instantaneous WUE (WUEinst) trends with increasing I. The fitted maximum values of A n, g s, T r, WUEi, and WUEinst and their saturation light intensities closely matched observations, unlike the NRH model. Despite the NRH model demonstrating high R 2 values for A n-I, g s-I, and T r-I modelling, it returned the maximum values significantly deviating from observed values and failed to generate saturation light intensities. It also inadequately represented WUE responses to I, overestimating WUE. Across different leaf temperatures, A n, g s, and T r of sweet sorghum displayed comparable light response patterns. Elevated temperatures increased maximum A n, g s, and T r but consistently declined maximum WUEi and WUEinst. However, WUEinst declined more sharply due to the disproportionate transpiration increase over carbon assimilation. Critically, sweet sorghum A n saturated at current atmospheric CO2 levels, with no significant gains under 550 μmol mol-1. Instead, stomatal closure enhanced WUE under elevated CO2 by coordinated g s and T r reductions rather than improved carbon assimilation. Nonetheless, this response diminished under simultaneously high temperature, suggesting intricate interplay between CO2 and temperature in modulating plant responses. These findings provide valuable insights into photosynthetic dynamics of sweet sorghum, aiding predictions of yield and optimization of cultivation practices. Moreover, our methodology serves as a valuable reference for evaluating leaf photosynthesis and WUE dynamics in diverse plant species.

SbYS1 and SbWRKY72 regulate Cd tolerance and accumulation in sweet sorghum.

SbYS1 and its upstream transcription factor SbWRKY72 were involved in Cd tolerance and accumulation and are valuable for developing sweet sorghum germplasm with high-Cd tolerance or accumulation ability through genetic manipulation. Cadmium (Cd) is highly toxic and can severely affect human health. Sweet sorghum, as an energy crop, shows great potential in extracting cadmium from Cd-contaminated soils. However, its molecular mechanisms of Cd-tolerance and -accumulation remain largely unknown. Here, we isolated a YSL family gene SbYS1 from the sweet sorghum genotype with high Cd accumulation ability and the expression of SbYS1 in roots was induced by cadmium. GUS staining experiment exhibited that SbYS1 was expressed in the epidermis and parenchyma tissues of roots. Further subcellular localization analysis suggested that SbYS1 was localized in the endoplasmic reticulum and plasma membrane. Yeast transformed with SbYS1 exhibited a sensitive phenotype compared to the control when exposed to Cd-NA (chelates of cadmium and nicotianamine), indicating that SbYS1 may absorb cadmium in the form of Cd-NA. Arabidopsis overexpressing SbYS1 had a longer root length and accumulated less Cd in roots and shoots. SbWRKY72 bound to the promoter of SbYS1 and negatively regulated the expression of SbYS1. Transgenic Arabidopsis of SbWRKY72 showed higher sensitivity to cadmium and increased cadmium accumulation in roots. Our results provide references for improving the phytoremediation efficiency of sweet sorghum by genetic manipulation in the future.

Genetic Variability Studies in Sweet Sorghum (Sorghum bicolor l.) Genotypes for Sugar and Biomass Related Traits

Sorghum bicolor (L. Moench) is an important crop in the semi-arid tropics of Africa and Southern Asia. Sweet sorghum is characterized by more rapid growth, higher biomass production, wider adaptation and greater potential for ethanol production. The present study was conducted to evaluate 33 sweet sorghum genotypes including two check varieties for different yield and sugar related traits. Analysis of variance revealed the presence of significant difference for all characters under the study. The genetic variability study revealed the presence of greater phenotypic co-efficient of variation (PCV) than genotypic co-efficient of variation (GCV) for most of the characters indicating the presence of the environmental effect. Stem girth, nodes per plant, biomass weight, cane weight, juice content and total soluble solids, total sugars were recorded high PCV and GCV. Plant height and cane height recorded moderate PCV and GCV. Except for plant height at 30 days after sowing (DAS)  all other characters plant height at 60 DAS, plant height at 90 DAS, cane height, nodes per plant, stem girth, biomass weight, cane weight, total biomass yield, juice yield, total soluble solids, total sugars, total reducing sugars and total non-reducing sugars showed high heritability estimates coupled with high genetic advance as percent of mean suggesting that, these characters are under the control of additive genes and phenotypic selection will be effective for these traits.

The effect of the moisture availability rate on the productivity and nutritional value of sorghum crops

Productivity reduced by drought is quite common. There can be up to 60.0% of the harvest losses. This is especially true for forage crops. The purpose of the current work was to identify the dependence of productivity and quality of green mass of sorghum crops on moisture availability during a vegetation period of plants. Sudan grass variety Alice, sugar sorghum variety Yuzhnoye, and sorghum-sudangrass hybrid variety Gustolistny were used as research objects. The study was carried out in the Rostov region. The soil of the experimental plot was ordinary carbonate black earth (chernozem). In order to study the variability of productivity and nutritional qualities, the years with the HTC level from 0.34 to 0.88 with an interval of 0.8–1.2 (2018–2022) were taken into account. The trials were conducted according to the methodology of the State Variety Testing. When the HTC increased from 0.34 to 0.88, there was a tendency to improve green mass productivity by 23.3–35.0% and decrease the protein percentage by 41.80–55.54%. A negative relationship between the amount of crude protein and the HTC value was revealed (r = –0.78... –0.92). The digestible protein yield decreased by 22.22–31.03% with increasing moisture content. The largest mean value was identified for the sorghum-sudangrass hybrid with 0.70 t/ha and the sweet sorghum variety with 0.71 t/ha. The variation coefficient of fiber content was 2.16–5.42%, which indicated weak variability of the trait over the years, and, consequently, a weak dependence on the moisture availability rate, which was confirmed by the correlation analysis (r = –0.03...0.32). The largest value of the metabolic energy was found in the sorghum-sudangrass hybrid (10.42–10.80 mJ/kg). At the same time, there was no dependence of this indicator, as well as the amount of feed units, on the moisture availability rate. The highest amount of digestible protein per feed unit was identified in sweet sorghum (83.4 g). A tendency to decrease this indicator by 22.6–42.5% was found as the HTC level increased (r = –0.69...–0.90).

Enhancing biomass conservation and enzymatic hydrolysis of sweet sorghum bagasse by combining pretreatment with ensiling and NaOH.

Lignocellulosic pretreatment is an important stage in biomass utilization, which usually requires high input. In this study, a low-cost method using combined ensiling and NaOH was developed for lignocellulosic pretreatment. Sweet sorghum bagasse (SSB) was ensiled for 21 days and then treated with diluted NaOH (0%, 1%, and 2%) for fermentation. The results showed that the application of Lactobacillus plantarum (L) reduced fermentation losses of the silages, mainly low water-soluble carbohydrate (WSC) and ammonia nitrogen loss. Meanwhile, the application of Lactobacillus plantarum and ensiling enzyme (LE) promoted lignocellulosic degradation, as evidenced by low neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (ADL), and hemicellulosic (HC) contents. The dominant bacterial genera were Lactobacillus, uncultured_bacterium_f_Enterobacteriaceae, and Pantoea after silage, which corresponded to the higher lactic acid and acetic contents and lower pH. The reducing sugar yields of SSB increased after combined pretreatment of silage and NaOH and were further enhanced by the 2% NaOH application, as evidenced by the high reducing sugar yield and microstructure damage, especially in the L-2% NaOH group and the LE-2% NaOH group, in which the reducing sugar yields were 87.99 and 94.45%, respectively, compared with those of the no additive control (CK)-0 NaOH group. Therefore, this study provides an effective method for SSB pretreatment to enhance biomass conservation.

Advancing safe bioenergy production from cadmium-contaminated sweet sorghum through mild synergistic pretreatment

Phytoremediation is an eco-friendly and cost-effective method for treating cadmium (Cd)-contaminated soil. However, safe disposal of harvested hyperaccumulators remains scarce. Herein, a mild synergistic pretreatment combining dilute acid and alkali pretreatment was developed for safe biorefining of the Cd-containing sweet sorghum, and Cd was centrally extracted into the acid pretreatment liquid in the first step. The results showed that the synergistic pretreatment was more effective in removing Cd from the biomass and overcoming biomass recalcitrance. During the synergistic pretreatment, the Cd concentration in biomass dramatically decreased from 4.03 to 0.00626 mg/kg, and a considerable amount of lignin and hemicelluloses in biomass was removed, facilitating enzymatic saccharification and safe bioenergy production. The optimal conditions of the synergistic pretreatment resulted in a total sugar yield of 81.6 wt %, which was 4.7-fold higher than that of the original biomass. This strategy holds promise for reducing the cost of industrial saccharification and is a valuable inspiration for the safe handling and resource utilization of Cd-containing biomass.

Use of hybridization to develop new sorghum varieties and hybrids

Hybridization is the main method for developing new breeding material, obtaining genetic variability, and combining desired traits. The purpose of the current work is to characterize new promising varieties and hybrids of sweet and grass sorghum developed by the “ARC “Donskoy” because of hybridization on a sterile and fertile basis. The study was conducted on the breeding field of the FSBSI “ARC “Donskoy”, Zernograd, Rostov region in 2021–2023. The zone is characterized by ordinary carbonate chernozem (3.2 % of humus, 10–40 mg/kg of phosphorus, 70–110 mg/kg of nitrogen, 300–500 mg per kg of soil of potassium). Meteorological conditions during the years of study (2021–2023) were contrasting: in 2022, HTC = 0.52 indicated average aridity and insufficient moisture with 0.81–0.82 in 2021 and 2023. The objects of the study were the varieties and hybrids of Sudan grass and sugar sorghum developed by the FSBSI “ARC “Donskoy”. As a result of hybridization on a sterile basis, there was developed a number of sorghumSudan hybrids (‘Jetta x Kudesnitsa’, ‘APV-1115 x Topolina’, ‘APV-1115 x FP’, ‘Dobrynya’, ‘Gordey’) and sweet sorghum hybrids (‘APV-115 x Yuzhnoye’, ‘Jetta x Severanay Vishnya’, ‘Duet’), allowing to obtain green mass yields of 51–63 and 47–49 t/ha, which was higher than the standard by 5–17 t/ha (10.8–37.0 %) and 5–7 t/ha (11.9–16.7 %) respectively. Using intervarietal hybridization, almost all varieties developed by the FSBSI “ARC “Donskoy” have been created. Among them there are the Sudan grass varieties ‘Alisa’, ‘Gratsiya’, ‘Anastasiya’, ‘Kudesnitsa’, ‘FP’ and the sweet sorghum varieties ‘Yuzhnoe’, ‘Feniks’, ‘Orfey’, ‘SK-20/334’, ‘Severanay Vishnya’ with a green mass yield of 40–48 and 34–38 t/ha, which is higher than that of standard varieties by 3–11 t/ha (8.1–29.7 %) and 7–11 t/ha (25.9–40.7 %), respectively. Thus, hybridization is the main method for developing new breeding material and combining the desired traits in new samples.

Carbon footprint of four bioethanol cropping systems in a temperate region

Under the EU Renewable Energy Directive (2009/28/EC), estimating biofuel GHG emissions is essential to gauge emissions reductions compared to fossil fuels. Within this framework, the carbon footprint (CF) was calculated for four bioethanol cropping systems: a maize-wheat-sorghum rotation without the harvest of crop residues (MWS), a maize-wheat-sorghum rotation with harvested crop residues (MWS-R), switchgrass (Sw), and continuous sweet sorghum (Ss). The estimation followed a life-cycle analysis strategy. The CF varied between 0.04 and 3.68 kg CO2-eq l − 1 ethanol. Switchgrass had the smallest CF and the highest ethanol yield per hectare (4,263 L [ha yr] − 1). However, for annual systems, Ss had the highest CF (3.68 kg CO2-eq l − 1 ethanol), 2 and 4 times larger than MWS-R and MWS systems. The soil preparation, planting, and post-planting emissions were 80% of the mean emissions in the annual cropping systems. By comparison, 60% of Sw’s CF came from post-planting, and 46% from fertilizers. In Sw, soil erosion accounted for 11% of the soil organic carbon lost in the MWS-R and Ss systems. In addition, Sw was the system with the most significant carbon sequestration (−1,957 kg CO2-eq [ha yr − 1]), a value corresponding to 94% of the CF of this bioethanol cropping system.

PRODUÇÃO DE BIOGÁS A PARTIR DE SILAGEM DE SORGO DOCE E RESÍDUOS ANIMAIS

The objective of this work is to quantify the biogas produced in batch-type benchtop biodigesters, from the anaerobic fermentation of sweet sorghum, stored in silos for 12 months, associated with goat and cattle waste, respectively. The input and output waste (biofertilizer) from the biodigesters was analyzed for physical (solid) and physical-chemical parameters (pH and electrical conductivity). The yield (Lbiogas.kg-1SVad), biogas productivity (Lbiogas.L-1reator.d-1) and the added volumetric organic load - VOLad (kgSV.L-1reator.d-1) were calculated. The work was conducted at the Rural Construction Laboratory of the Federal University of Vale do São Francisco located on the Agricultural Sciences Campus. The hydraulic retention time was 30 days in the randomized block experimental design. The constructed biodigesters performed well in quantifying the production of biogas from organic substrate, promoting ideal conditions for the anaerobic digestion process to occur without oxygen contamination. However, there was no significant difference in biogas production between treatments. Treatment T2 (cattle manure) showed the highest yield (240 Lbiogas.kg-1SVad) with an average added volumetric organic load of 8 kgSV.L-1reactor.d-1. Treatment T5 (sorghum 50% + beef 50%) presented a higher numerical value of biogas productivity (0.0703 Lbiogas.L-1reator.d-1) in relation to the other treatments, however this difference was not significant at 5% probability using the Tukey test.

Strain engineering of Bacillus coagulans with high osmotic pressure tolerance for effective L-lactic acid production from sweet sorghum juice under unsterile conditions

Open unsterile fermentation of the low-cost non-food crop, sweet sorghum, is an economically feasible lactic acid biosynthesis process. However, hyperosmotic stress inhibits microbial metabolism and lactic acid biosynthesis, and engineering strains with high osmotic tolerance is challenging. Herein, heavy ion mutagenesis combined with osmotic pressure enrichment was used to engineer a hyperosmotic-tolerant Bacillus coagulans for L-lactic acid production. The engineered strain had higher osmotic pressure tolerance, when compared with the parental strain, primarily owing to its improved properties such as cell viability, cellular antioxidant capacity, and NADH supply. In a pilot-scale open unsterile fermentation using sweet sorghum juice as a feedstock, the engineered strain produced 94 g/L L-lactic acid with a yield of 91 % and productivity of 6.7 g/L/h, and optical purity of L-lactic acid at the end of fermentation was 99.8 %. In short, this study provided effective and low-cost approach to produce polymer-grade L-lactic acid.

Effect of Tillage and Nitrogen Rates on Fodder Productivity and Juice Quality of Sweet Sorghum (Sorghum bicolar L.) in Himalayan Foothills of India

Effect of Tillage and Nitrogen Rates on Fodder Productivity and Juice Quality of Sweet Sorghum (Sorghum bicolar L.) in Himalayan Foothills of India

Cell-type-specific transcriptomics uncovers spatial regulatory networks in bioenergy sorghum stems.

Bioenergy sorghum is a low-input, drought-resilient, deep-rooting annual crop that has high biomass yield potential enabling the sustainable production of biofuels, biopower, and bioproducts. Bioenergy sorghum's 4-5 m stems account for ~80% of the harvested biomass. Stems accumulate high levels of sucrose that could be used to synthesize bioethanol and useful biopolymers if information about cell-type gene expression and regulation in stems was available to enable engineering. To obtain this information, laser capture microdissection was used to isolate and collect transcriptome profiles from five major cell types that are present in stems of the sweet sorghum Wray. Transcriptome analysis identified genes with cell-type-specific and cell-preferred expression patterns that reflect the distinct metabolic, transport, and regulatory functions of each cell type. Analysis of cell-type-specific gene regulatory networks (GRNs) revealed that unique transcription factor families contribute to distinct regulatory landscapes, where regulation is organized through various modes and identifiable network motifs. Cell-specific transcriptome data was combined with known secondary cell wall (SCW) networks to identify the GRNs that differentially activate SCW formation in vascular sclerenchyma and epidermal cells. The spatial transcriptomic dataset provides a valuable source of information about the function of different sorghum cell types and GRNs that will enable the engineering of bioenergy sorghum stems, and an interactive web application developed during this project will allow easy access and exploration of the data (https://mc-lab.shinyapps.io/lcm-dataset/).

Sweet Sorghum for Biofuel Production in Sub-Tropical India

Sweet sorghum (Sorghum bicolor L. Moench), a sugar crop with wider adaptation and high potential for bioenergy and ethanol production is expected to meet food, feed, fodder, fuel and fibre demands. It produces high biomass (50-80 t/ha) and alcohol (1500-2800 l/ha) and multiple income opportunities exist with this crop. Some sweet sorghum lines attain juice yields of about 78% of total plant biomass, containing from 15 to 23% soluble fermentable sugars which are composed mainly of sucrose (70–80%), fructose and glucose. Due to its short growing period (3-4 months), it could be cultivated and supplied during the lean period of sugarcane crushing thus extending the crushing period before and after sugarcane crushing and stretch the sugar mill operation. The major advantage with this crop is that no CAPEX is required when used in a sugar mill system as same machinery can be used for crushing and fermentation. It will help farmers to fetch additional income and provide an opportunity for better utilization of industrial facilities during sugarcane off-season. Promising sweet sorghum genotypes developed by ICAR-IIMR, Hyderabad are being tested for their suitability to sub-tropical conditions in February and June-July plantings at the NSI, Kanpur to establish a sustainable cropping system. Five sweet sorghum genotypes were tested during kharif 2021 for sweet sorghum productivity traits. The fresh stalk yield ranged from 45-60 t/ha and based on TRS, maximum alcohol percentage in wash was observed in three varieties, i.e., Phule Vasundhara, CSH 22SS and SSV 74 which was 8.4%, 8.38% and 7.8% respectively. Maximum ethanol yield of 53.05 L/T was recorded in CSH 22 SS followed by SSV 74 (50.93 L/T). Phule Vasundhara, with a highest stalk yield of 60 t/ha recorded highest ethanol content of 2837 L/ha followed by CSH 22SS (2780 L/ha) and SSV 74 (2411 L/ha).

Novel Batch and Repeated-Batch Butanol Fermentation from Sweet Sorghum Stem Juice by Co-Culture of Arthrobacter and Immobilized Clostridium in Scaled-Up Bioreactors

This research aims to study butanol fermentation from sweet sorghum stem juice (SSJ) by immobilized Clostridium beijerinckii TISTR 1461 cells on bamboo chopsticks using Arthrobacter sp. as an efficient bacterium for creating anaerobic conditions in scaled-up bioreactors. For batch culture in a 1-L screw-capped bottle, a butanol concentration (PB), butanol productivity (QB), and butanol yield (YB/S) were 12.09 g/L, 0.26 g/L·h and 0.28 g/g, respectively. These values were ~8 to 14% higher than those of a single culture using oxygen-free nitrogen (OFN) gas to generate anaerobic conditions. When butanol fermentation by the co-culture was scaled-up to 5-L and 30-L stirred-tank fermenters, the butanol production efficiency was not different from that using the 1-L bottles. Additionally, repeated-batch butanol fermentation in the 1-L bottles by the co-culture was successfully operated for four successive cycles with high butanol production. All results clearly indicate that Arthrobacter sp. is promising for creation of anaerobic conditions for butanol production by immobilized Clostridium in large scale bioreactors.

Effects of cutting height and storage length on fermentation characteristics, microbial community, co-occurrence networks, potential functionality and pathogenic risk of fermented sweet sorghum stem

Postharvest management strategies like cutting height and anaerobic fermentation may affect the microbial risk of vegetables. This study evaluated the effects of cutting height and storage length on the fermentation characteristics, microbial diversity, co-occurrence networks, potential functionality and pathogenic risk of sweet sorghum stem (SSS). Fresh SSS harvested at two cutting heights (15 cm, F15; 45 cm, F45) was spontaneously fermented (S15 and S45) for 2, 4, 8, 16, 32 and 64 days. Decreasing the cutting height of SSS increased the dry matter, water-soluble carbohydrate content as well as Acinetobacter (23.0% vs. 44.9%) and Klebsiella (1.84% vs. 6.58%) proportion but decreased the crude protein content (P < 0.05). After fermentation, both cutting heights presented desirable fermentation. Anaerobic fermentation promoted the Glycolysis pathway (0.009 vs. 0.018) and related enzymes (l-lactate dehydrogenase, etc.) associated with lactate synthesis, but suppressed the degradation pathways of valine, leucine, isoleucine (0.011 vs. 0.003) and lysine (0.008 vs. 0.002). In microbial phenotype analysis, although F15 had higher proportions of ‘Potentially Pathogenic’ than F45, this undesirable phenotype declined to negligible levels via fermentation. These results concluded that, for SSS, concerns about the risk of microbial contamination and pathogens from low cutting height can be dispelled by well fermentation.

Hydrogen and Fatty Acid Production by Dark Fermentation of Sweet Sorghum Stalks as an Efficient Pre-treatment for Energy Recovery Before Their Bioconversion into Methane

Hydrogen and Fatty Acid Production by Dark Fermentation of Sweet Sorghum Stalks as an Efficient Pre-treatment for Energy Recovery Before Their Bioconversion into Methane

Major impacts of widespread structural variation on sorghum.

Genetic diversity is critical to crop breeding and improvement, and dissection of the genomic variation underlying agronomic traits can both assist breeding and give insight into basic biological mechanisms. Although recent genome analyses in plants reveal many structural variants (SVs), most current studies of crop genetic variation are dominated by single-nucleotide polymorphisms (SNPs). The extent of the impact of SVs on global trait variation, as well as their utility in genome-wide selection, is not yet understood. In this study, we built an SV data set based on whole-genome resequencing of diverse sorghum lines (n = 363), validated the correlation of photoperiod sensitivity and variety type, and identified SV hotspots underlying the divergent evolution of cellulosic and sweet sorghum. In addition, we showed the complementary contribution of SVs for heritability of traits related to sorghum adaptation. Importantly, inclusion of SV polymorphisms in association studies revealed genotype-phenotype associations not observed with SNPs alone. Three-way genome-wide association studies (GWAS) based on whole-genome SNP, SV, and integrated SNP + SV data sets showed substantial associations between SVs and sorghum traits. The addition of SVs to GWAS substantially increased heritability estimates for some traits, indicating their important contribution to functional allelic variation at the genome level. Our discovery of the widespread impacts of SVs on heritable gene expression variation could render a plausible mechanism for their disproportionate impact on phenotypic variation. This study expands our knowledge of SVs and emphasizes the extensive impacts of SVs on sorghum.