Fungi associated with sorghum grain from Argentina

Sorghum (Sorghum bicolor (L.) Moench) is an important cereal produced in and exported from Argentina. The risk of contamination by mycotoxins is related to the mycoflora associated with the sorghum grain. This paper reports on the identification of internal mycoflora of sorghum grain harvested in Argentina in 1991, 1992 and 1993, years with different total rainfall levels. A mycological survey was carried out on sorghum samples, from a location at the humid Argentinian pampa, using a Fusarium/dematiaceous fungi selective medium. The relative density of the prevalent fungal genera were statistically compared. Genus Fusarium was the most prevalent component of the internal seedborne mycoflora in the three harvest seasons. Genera Alternaria, Phoma, Penicillium and Aspergillus were also isolated. The predominant Fusarium was F. moniliforme and the most frequently isolated species of Alternaria, Phoma, Penicillium and Aspergillus were Alt. alternata, Pho. sorghima, Pen. funiculosum and Asp. flavus, respectively. This is the first report of the isolation of Fusarium napiforme in sorghum grain in Argentina. This revised version was published online in June 2006 with corrections to the Cover Date.     

Screening for grain polyphenol variants from high-tannin sorghum somaclones

Several hundred somaclones established from plants regenerated from embryogenic callus cultures of six high tannin sorghum lines were screened for variants with altered levels of polyphenols in the grain. Grain from over 6000 plants including the R ₁ (primary), R₂, and R₃ generations were analyzed for total phenols, flavan-4-ols, and proanthocyanidins (condensed tannins). Although many variants which had lost the ability to synthesize chlorophyll were found, none of the somaclones tested had lost or greatly reduced the ability to synthesize any of the polyphenols assayed. However, we did observe statistically significant differences in polyphenol concentration between tissue culture-derived R₁ plants and the parental controls. In the R₂ generation the proportion of somaclones which differed significantly from the parents varied from 47% to 68% depending upon genotype. The average somaclonal variation rate and somaclonal variant frequency estimated in the tested population for the three polyphenol characteristics ranged from 37.3% to 40.7% and 5.3% to 7.8%, respectively. Variants with decreased levels of polyphenols were usually epigenetic and reverted back to normal levels in subsequent generations, but those with increased levels usually persisted after two meiotic cycles, indicating they are heritable. Variants with polyphenol levels increased up to 80% or decreased by 30% were selected for in the R₃ generation.     

Activated carbons prepared from phosphoric acid activation of grain sorghum.

The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 degrees C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The preparation conditions, e.g., activation duration, phosphoric acid concentration, and activation temperature, have been varied to determine the optimal processing conditions. The optimal activation conditions for the highest surface areas have been determined to be 600 and 500 degrees C with a phosphoric acid concentration of 35% for the one-stage and two-stage processes, respectively. The two-stage process has been found to greatly enhance the porosity development, especially the microporosity.     

Response of grain sorghum to enhanced-ammonium supply

Two greenhouse experiments were conducted to examine the effects of increased levels of soil NH ₄ ⁺ on the growth and yield of grain sorghum (Sorghum bicolor (L.) Moench). Nitrogen was supplied as urea plus the nitrification inhibitor nitrapyrin (enhanced-NH ₄ ⁺ supply) or as a 41 molar ratio of CA(NO₃)₂ and Mg(NO₃)₂ at rates of 0 to 450 mg N kg^–1 soil in 37.5 mg N increments. Enhanced-NH ₄ ⁺ supply, in comparison to the NO₃ treatment, increased grain yield 15 and 18% in the two experiments. In one experiment this yield increase occurred through increased number of kernels and in a second experiment, through increased weight of kernels. During the first 28 days after plant emergence, the number of leaves, stalk width, plant weight, and plant N content were greater with enhanced-NH ₄ ⁺ supply than with NO ₃ ^– . However, at harvest total plant weight and plant N content were minimally affected by enhanced-NH ₄ ⁺ supply.     

Experimental studies for levulinic acid production from whole kernel grain sorghum.

Levulinic acid has potential as an important basic chemical material. This study proposed a method of making levulinic acid using abundant and low cost whole kernel sorghum grain as the raw material. Flour made from grinding whole kernel sorghum grains was blended with 2%, 5% and 8% aqueous solutions of sulfuric acid. Mixtures were heated to 160 or 200 degrees C in a pressurized reactor. A stepwise heating scheme helped improve the yield of levulinic acid. Levulinic acid yield was determined based on sorghum flour content, as opposed to total sorghum mass. Levulinic acid yield increased as reaction temperature increased. Higher sulfuric acid concentration also significantly increased the levulinic acid yield. However, flour loading had an adverse effect on levulinic acid yield. A maximum yield of 32.6% levulinic acid was achieved at 200 degrees C, 8% sulfuric acid concentration and 10% flour loading. A linear regression model was capable of predicting the levulinic acid yield with respect to effects of reaction temperature, mineral acid concentration and flour loading (R2 = 0.88).     

Toxigenicity of Clostridium histolyticum

Nishida, Shoki (Kanazawa University, Kanazawa, Japan), and Masaaki Imaizumi. Toxigenicity of Clostridium histolyticum. J. Bacteriol. 91:477-483. 1966.-From 234 soil samples, 21 strains of Clostridium histolyticum of different levels of alpha-toxigenicity were isolated by a new method specially designed for the isolation of this species. The alpha-toxigenicity of freshly isolated strains and of stock strains was closely associated with the potentiality for sporulation, growth, and smooth-colony formation. The presence of sugars, particularly xylose and arabinose, was inhibitory for growth. A few controversies on the biological properties of this species seem to be due to disregard for the growth-inhibiting effects of these sugars.     

Potential gain from selection for yield stability in two grain sorghum populations

Summary Maximum yield under highly unpredictable environments should be associated with selection of genotypes with superior performance across good and poor environments. Several stability parameters have been proposed to identify superior genotypes over a wide range of environments. None of these has been used as selection criteria, however, because of their low heritability. The objective of the study presented here was to compare the relative efficiency of predicted gain from indirect selection among three stability parameters: the coefficient of regression (b), deviation from regression (S _d ² ), and principal components scores (PC) from the AMMI model; two indices including mean yield and a stability parameter; and three indices involving yield at the best, the worst, and an intermediate environment. Two hundred S₁ families from each of two sorghum populations (TP24D and KP9B) were evaluated at four dry-land evironments over 2 years. The low heritability estimates and the low genetic correlation between the various stability parameters and mean yield resulted in their low relative efficiency as indirect selection criteria for high yield across environments. However, when the parameters were combined with mean yield over all to create indices, the relative efficiency increased for all the environments. In terms of resource allocation, these indices were not as efficient as mean productivity, rank summation, and selection index that involved fewer environments in their estimation.Contribution no. 9820 of Agricultural Research Division, Univ. of Neb. and no. 92-203-J of Kansas Exp. Stn.     

Biochemical characterization of the major sorghum grain peroxidase

The major cationic peroxidase in sorghum grain (SPC4) , which is ubiquitously present in all sorghum varieties was purified to apparent homogeneity, and found to be a highly basic protein (pI approximately 11). MS analysis showed that SPC4 consists of two glycoforms with molecular masses of 34,227 and 35,629 Da and it contains a type-b heme. Chemical deglycosylation allowed to estimate sugar contents of 3.0% and 6.7% (w/w) in glycoform I and II, respectively, and a mass of the apoprotein of 33,246 Da. High performance anion exchange chromatography allowed to determine the carbohydrate constituents of the polysaccharide chains. The N-terminal sequence of SPC4 is not blocked by pyroglutamate. MS analysis showed that six peptides, including the N-terminal sequence of SPC4 matched with the predicted tryptic peptides of gene indice TC102191 of sorghum chromosome 1, indicating that TC102191 codes for the N-terminal part of the sequence of SPC4, including a signal peptide of 31 amino acids. The N-terminal fragment of SPC4 (213 amino acids) has a high sequence identity with barley BP1 (85%), rice Prx23 (90%), wheat WSP1 (82%) and maize peroxidase (58%), indicative for a common ancestor. SPC4 is activated by calcium ions. Ca2+ binding increased the protein conformational stability by raising the melting temperature (Tm) from 67 to 82 degrees C. SPC4 catalyzed the oxidation of a wide range of aromatic substrates, being catalytically more efficient with hydroxycinnamates than with tyrosine derivatives. In spite of the conserved active sites, SPC4 differs from BP1 in being active with aromatic compounds above pH 5.     

Amino acid composition of two varieties of sorghum grain

The purpose of the present study was to investigate the animo acid composition of 5 different samples of C Hara sorghum grain and to estimate the biological values of their protein fraction by means of some chemical indexes, such as the the chemical score, biological value, essential amino acid index and the protein balance index.The figures obtained were compared with those of 5 different samples of sorghum grain belonging to the variety NK 121 and with those of common maize grain. C Hara appeared to have the highest amount of crude protein with the lowest biological value, but when protein digestibility figures were considered, C Hara had the highest content of biologically utilizable proteins.     

Evaluation of Magadi soda-treated sorghum grain for young broilers

Magadi soda (MS) is a commercially available form of sodium sesquicarbonate in Kenya. Soaking high-tannin sorghum (HTS) grain (2.5% catechin equivalents) in a 6 g l⁻¹ MS solution was shown to eliminate measurable tannin content. A feeding trial was conducted to investigate the performance of broiler chicks fed soyabean-based diets containing HTS or MS-treated HTS as the sole cereal source from 1-3 weeks of age. A third diet containing sorghum with no detectable tannin content served as the control. Diets containing 220 g kg⁻¹ crude protein were fed to 6 pens of 5 birds per pen for each treatment from 1-2 weeks of age and to 4 pens of 4 birds per pen per treatment in weeks 2-3. Feed intake, weight gain and feed efficiency (FE) were determined weekly. Apparent dry matter digestibility (DMD), metabolizable energy (AMEn) and nitrogen retention (NR) were measured over the last 3 days of each period. Gain and feed intake were not affected by treatment (P > 0.05), but FE and DMD were lower (P < 0.05) for the HTS diet than for the MS-treated HTS and control diets, which themselves were similar. Absolute NR was higher (P < 0.05) for the control diet than either of the HTS diets in week 2 but was the same for all diets in week 3. As % of intake, NR was higher (P < 0.05) for the control in both weeks 2 and 3 than for the HTS diets, although this was improved (P < 0.05) by MS treatment in week 2. AMEn values showed a similar pattern to that for NR in week 2 but in week 3 was the same for the MS-treated HTS and control diets, which were higher than the HTS diet (P < 0.05). Though total tannin content did not influence growth of birds in this study, MS treatment of HTS did reduce deleterious effects on FE, AMEn and NR as a % of intake.     

Supercritical CO2 extraction of lipids from grain sorghum dried distillers grains with solubles

Experiments were carried out on a lab supercritical CO(2) extraction system to determine the effects of extraction conditions, including mass ratio of CO(2) consumed to distillers dry grain with solubles (DDGS) extracted, extraction pressure, extraction temperature and time, on yield and composition of extracted lipids. A maximum lipid yield of 150 g/kg DDGS was achieved with a mass ratio approximately 45, an extraction pressure at 27.5 MPa, an extraction temperature at 70 degrees C and an extraction time of 4 h. Under these extraction conditions, the contents of tocols, phytosterols, policosanols and free fatty acids were 0.44, 15.6, 31.2 and 155.3 mg/g in the extract. Experimental results indicated that shorter extraction time and higher flow rate of CO(2) can achieve higher contents of tocols, phytosterols and policosanols but lower content of free fatty acids in the lipid extract. Extraction conditions had no observed effects on the composition of free fatty acids in the extract. Palmitic, oleic and linoleic acids were three main free fatty acids extracted and constituted about 94% of all free fatty acids.     

Genetic variation for gas exchange rates in grain sorghum

Carbon assimilation rate (A) and stomatal conductance (g) are highly correlated. However, the slope of the A versus g relationship differs among species and environments resulting in differences in gas exchange efficiency which should reflect water use efficiency. The objective of this research was to determine the genetic variation for A and g in grain sorghum (Sorghum bicolor [L.] Moench.). Field experiments were conducted using 30 sorghum hybrids with four water supply treatments. A, g, and leaf water potential (Ψ_w) of individual leaves were monitored every 15 to 20 days. Significant genetic variation existed among the hybrids for A and g. Plant age and water supply also affected A and g as expected. When A was regressed on g for each hybrid, large and significant differences existed among the slopes, implying differences in intrinsic gas exchange efficiency. The regression analysis of A and g versus Ψ_w suggested that A was more sensitive than g to increasing water stress. Genetic differences in the rate of change in A as water stress increased were observed. Regression analysis was used to evaluate the individual hybrid response relative to other hybrids. Twofold difference in slopes existed for A. These results provide evidence for genetic variation in gas exchange rates which might directly contribute to whole plant water use efficiency and productivity.     

Freezing points and small-scale deicing tests for salts of levulinic acid made from grain sorghum

Deicers from renewable resources are needed to overcome the disadvantages of using traditional deicers. Salts made from levulinic acid produced using grain sorghum as raw material were tested as road deicing agents. Freezing points of these salts viz., sodium levulinate, magnesium levulinate and calcium levulinate along with rock salt (sodium chloride) were determined according to American Society for Testing and Materials (ASTM) D 1177-94 standard at concentrations of 10, 20, 30 and 40 % w/w. There were significant differences among the freezing points of the salts. Freezing points for rock salt, sodium levulinate, calcium levulinate and magnesium levulinate, for different concentrations, were in the ranges of -6.6 to -20.5, -2.9 to -15.0, -2.1 to -7.8 and -1.5 to -6.5 degrees C, respectively. Deicing effectiveness of the salts of levulinic acid were investigated by conducting small-scale deicing tests with aqueous solutions of various salt concentrations (2%, 5% and 10%) in a laboratory freezer and by spraying the deicer on a graveled surface covered by ice and snow with the average temperature during the testing at -2.7 degrees C. Deicing capabilities of the three salts of levulinic acid differed. At -2.7 degrees C, all three salts caused melting of the ice. Among the different levulinates studied sodium levulinate was the most effective deicing agent. These salts of levulinates could be a viable replacement for traditional deicers and could help in reducing the disadvantages of traditional deicers.