Enhancing the anaerobic digestion of corn stalks using composite microbial pretreatment

A composite microbial system (XDC-2) was used to pretreat and hydrolyze corn stalk to enhance anaerobic digestion. The results of pretreatment indicated that sCOD concentrations of hydrolysate were highest (8,233 mg/l) at the fifth day. XDC-2 efficiently degraded the corn stalk by nearly 45%, decreasing the cellulose content by 22.7% and the hemicellulose content by 74.1%. Total levels of volatile products peaked on the fifth day. The six major compounds present were ethanol (0.29 g/l), acetic acid (0.55 g/l), 1,2-ethanediol (0.49 g/l), propionic acid (0.15 g/l), butyric acid (0.22 g/l), and glycerine (2.48 g/l). The results of anaerobic digestion showed that corn stalks treated by XDC-2 produced 68.3% more total biogas and 87.9% more total methane than untreated controls. The technical digestion time for the treated corn stalks was 35.7% shorter than without treatment. The composite microbial system pretreatment could be a cost-effective and environmentally friendly microbial method for efficient biological conversion of corn stalk into bioenergy.     

玉米感染禾谷镰刀菌后PAL、POD活性和同工酶谱的变化

为了明确苯丙氨酸解氨酶活和过氧化物酶活与玉米对镰刀菌茎腐病的抗性关系,探讨玉米对镰刀菌茎腐病的抗病机制及其在玉米抗病性鉴定中的利用,用禾谷镰刀菌孢子悬浮液对抗病品种陕单931和感病品种西农11号在抽雄初期进行接种,并于接种后测定茎秆髓部组织内的PAL,POD活性变化以及POD同工酶谱的变化。结果表明,玉米植株受镰刀菌侵染后,抗病品种的PAL酶活上升快,活性强,且形成两个活性高峰,高活性时间持续长;感病品种PAL酶活上升慢,活性相对较弱,且只形成一个峰,高活性持续时间短。抗病品种POD酶活峰值高,感病品种峰值低;抗病品种高酶活持续的时间长,感病品种高酶活持续的短。POD同工酶谱研究表明,抗、感品种POD同工酶带都有增多。抗病品种增5条,感病品种新增2条。PAL活性变化、POD活性变化及同工酶谱酶活变化与其对茎腐病的抗性有密切的关系,可作为抗病育种的生理生化指标。     

Toxicity to Rats of Corn Invaded by Chaetomium globosum

Of 53 isolates of Chaetomium globosum Kunze isolated from corn, manufactured feed, and fiberboard, grown on autoclaved corn, and fed to rats, 25 were lethal within 4 to 6 days. Thirty-six single ascospore cultures of one isolate were uniformly lethal when similarly grown and fed to rats. Incubation of the fungus on corn for 6 to 8 weeks resulted in greater toxicity than shorter incubation times. Premortem symptoms indicated damage to the central nervous system of the affected animals, and postmortem lesions included hemoglobinuria, hemorrhagic enteritis, and subdural hemorrhaging. Corn invaded by C. globosum and toxic to rats had no detectable effects on swine when fed as their sole ration for 6 weeks, and appeared to be consumed with relish. The toxic substance was best obtained by defatting the fungus-invaded corn with petroleum ether (bp, 60 to 70 C), extraction with acetone, and further purification by elution from a silica gel column with acetone and 5% acetone in chloroform.     

一株纤维素降解菌的分离、鉴定及对 玉米秸秆的降解特性

[目的]获得高产纤维素酶细菌菌株,探讨以氨化预处理玉米秸秆为底物时的纤维素酶产酶特性及底物降解特性,探讨纤维素酶作用机理,提高玉米秸秆利用率.[方法]用LB培养基分离并纯化菌株,羧甲基纤维素钠培养基培养、刚果红染色进行初步筛选.考察氨化预处理对底物降解率、产酶能力的影响.通过形态特征观察及16S rRNA、Biolog鉴定菌株.[结果]分离到一株高效纤维素降解菌NH11,经鉴定为枯草芽孢杆菌(Bacillus subtilis). 30℃、发酵5d时,预处理前后玉米秸秆降解率分别为14.24％和24.73％.30℃、pH 7.2时,处理组CMC酶活力峰值处为153.84 U/mL,FPA酶活力为197.24 U/mL,比未处理组分别高出11.45％和10.59％.[结论]NH11具有较高的纤维素酶产酶能力,氨化预处理能够提高菌株对玉米秸秆的降解率.该菌株在秸秆堆肥、制作食用菌培养基和制取反刍动物粗饲料方面具有很高的应用价值.     

Mitochondrial DNA restriction map and cytochrome c oxidase subunits I and II sequence divergence of corn stalk borer Sesamia nonagrioides (Lepidoptera: Noctuidae)

Corn stalk borer Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) is among the most important insect pests of corn in the Mediterranean basin. The mitochondrial DNA of this insect was purified and a restriction map was constructed. The size of the mtDNA genome is 16.3 kb. Genetic analysis of four corn stalk borer populations, collected from Greece (three populations) and Spain (one population), was undertaken using DNA sequences of the mtDNA cytochrome oxidase (CO) I and II genes. Sequencing of a 2079 bp region of these genes revealed 25 polymorphic sites among the populations. Five molecular RFLP markers, located in the mtDNA COI and COII genes, were surveyed, and two different haplotypes were detected. Phylogenetic analysis based on COI/COII nucleotide sequences revealed genetic differentiation between samples, and the results are discussed in relation to the geographic distribution of the corn stalk borer in two Mediterranean countries.     

Mitochondrial DNA Restriction Map and Cytochrome c Oxidase Subunits I and II Sequence Divergence of Corn Stalk Borer Sesamia nonagrioides (Lepidoptera: Noctuidae)

Corn stalk borer Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) is among the most important insect pests of corn in the Mediterranean basin. The mitochondrial DNA of this insect was purified and a restriction map was constructed. The size of the mtDNA genome is 16.3 kb. Genetic analysis of four corn stalk borer populations, collected from Greece (three populations) and Spain (one population), was undertaken using DNA sequences of the mtDNA cytochrome oxidase (CO) I and II genes. Sequencing of a 2079 bp region of these genes revealed 25 polymorphic sites among the populations. Five molecular RFLP markers, located in the mtDNA COI and COII genes, were surveyed, and two different haplotypes were detected. Phylogenetic analysis based on COI/COII nucleotide sequences revealed genetic differentiation between samples, and the results are discussed in relation to the geographic distribution of the corn stalk borer in two Mediterranean countries.     

土壤添加玉米秸秆对小麦Pb毒害缓解效应

采用室内盆栽和网室盆栽的方法研究了Pb污染土壤上玉米秸秆对小麦幼苗生物效应、成熟期籽粒Pb含量和蛋白质含量以及产量性状的影响,探讨了玉米秸秆缓解Pb毒害小麦的生理机制.结果表明,添加3g/kg和6g/kg的玉米秸秆对Pb污染土壤上小麦幼苗生长有明显的促进作用,能有效缓解Pb对小麦的毒害.具体表现为,与对照相比,小麦幼苗根长、芽长、植株干重增大,叶绿素含量和根系活力升高,过氧化物酶(POD)和超氧化物歧化酶(SOD)同工酶活性以及丙二醛(MDA)含量下降,小麦成熟期籽粒Pb含量降低,蛋白质含量以及生物产量升高.     

不同培养料和发酵次数栽培巴氏菇比较

分别以玉米秸秆和稻草为培养料栽培巴氏菇,对菌丝生长性状进行对比;同时,在我国传统发酵栽培方法的基础上,将三次发酵法与二次发酵法进行了对比。试验结果表明:利用玉米秸秆栽培的巴氏菇在发菌速度及子实体质量和产量上均优于稻草;培养料经过3次发酵更适宜巴氏菇生长。经过3次发酵的玉米秸秆培养料栽培的巴氏菇产量和生物学效率分别为7.7 kg/m2和27.5%,子实体粗蛋白含量44.89%,可溶性糖含量44.01%,18种氨基酸总量31.70%,明显高于2次发酵的玉米秸秆培养料及2次、3次发酵的稻草培养料。     

Thermogravimetric kinetics of corn stalk pretreated by oleaginous fungi Cunninghamella echinulata

The thermogravimetric and composition of corn stalk pretreated by oleaginous fungi Cunninghamella echinulata had been studied in this paper. Results indicated that pretreatment by oleaginous fungi C. echinulata could decrease the activation energy and make the pyrolysis more efficient and energy-saving. By bio-pretreatment, the contents of elements agreed with the weight loss, sugar content, and oil contents, especially the sulfur content was greatly decreased, greatly eliminating the inventory of gas contamination such as the emission of SOx and making the pyrolysis more environmentally friendly. Therefor, corn stalk with sugar pretreated by oleaginous fungi C. echinulata should be a good pyrolysis material to obtain high quality bio-oil.     

Systemic infection of stalks and ears of corn hybrids by <Emphasis Type="Italic">Aspergillus parasiticus</Emphasis>

This study was conducted to explore systemic infection by the Aspergillus flavus group into corn ears via the stalk. An A. parasiticus mutant which produces norsolorinic (NOR) acid (a visible orange intermediate of the aflatoxin biosynthetic pathway) was used in field studies to monitor systemic infection of corn stalk and ear tissues. Corn hybrids resistant and susceptible to aflatoxin contamination were grown in the field and inoculated prior to tasseling by inserting A. parasiticus infested toothpicks into stalks between the 5th and 6th node below the lowest ear shoot. Beginning 2 weeks after inoculation, systemic infection by the NOR mutant was assessed weekly by collecting ear shank tissue and stalk tissue from the nodes between the infection sites and the developing ears. Ears were collected at the end of the growing season to determine the level of kernel infection by the NOR mutant. In two separate studies, the A. parasiticus NOR mutant was isolated from stalk tissues at all of node positions and ear shank tissue from several susceptible corn hybrid plants at the first harvest date 2 weeks after inoculation. The NOR mutant was also isolated from stalk and ear tissue of a resistant hybrid. The NOR mutant was only isolated from kernels of susceptible hybrids in 2003 and 2004. Infection rates of kernels in infected ears were very low (<1%). In 2005, the fungus was found in only one kernel from an ear of the resistant hybrid. The NOR mutant was not isolated from stalks, ears, or kernels from control (uninoculated) plants grown in the plots with inoculated plants. Although infection levels of corn kernels were low, systemic movement of the A. parasiticus up the stalk appears to be another possible route to infection of developing corn ears.     

Feeding behavior and growth of corn earworm (Lepidoptera: noctuidae) larvae on Bacillus thuringiensis-treated (dipel 4L) and untreated meridic diet

The effect of Dipel 4L in artificial diet on feeding behavior, occurrence on a specific diet, and growth of corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), was assessed in short-term tests. Third-, fourth-, and fifth-stage laboratory-reared and feral corn earworm larvae were evaluated. Arenas used for each assay included a non-Dipel diet, Dipel-containing diet, and a combination of the two diets. Larval activity was observed immediately after exposure to diet and at 6 and 18 h for third instars and at 6, 8, and 24 h for fourth and fifth instars, respectively. Feral and laboratory-reared third, fourth, and feral fifth instars avoided Dipel-treated diet when more suitable food was available. Third and fourth instars consistently preferred non-Dipel-containing diet when presented a choice of foods. Corn earworm growth was delayed when larvae were subjected to Dipel-treated diet in choice and no-choice assays compared with larvae provided untreated diet. Larvae presented a choice of diets grew more rapidly than those presented Dipel-treated diets in no choice arenas. Larval feeding frequency and weight gain were superior when larvae were supplied untreated diet than when restricted solely to a Dipel-treated diet. Larvae presented a choice of diets spent more time feeding and fed more frequently on untreated diet than Dipel-treated food. These data indicate that corn earworm presented a choice of Bacillus thuringiensis (Bt) and non-Bt diets may have an increased probability of completing development compared with those restricted to Bt-laced sources.     

Effect of Watering Regimen on Injury to Corn and Grain Sorghum by Pratylenchus Species

The effect of simulated rainfall frequency on the pathogenicity of Pratylenchus zeae and P. brachyurus was studied in four greenhouse experiments. Corn and grain sorghum were watered at different intervals during predetermined cycles to create a gradient of water-stressed plants. Each experiment included nematode and uninoculated treatments. Growth reaction of plants to different frequencies of watering was significant but was not affected by the presence of nematodes. Pratylenchus zeae numbers differed among watering regimens on corn but not on sorghum. Numbers of P. brachyurus did not differ among watering regimens on corn or sorghum. Both lesion nematode species were harmful to corn, but sorghum increased plant growth in response to P. brachyurus. It is concluded that water stress is not the only environmental factor that influences the pathogenicity of these two species on corn and sorghum.     

Biodetrimental effects of the Corn hybrids,Neemazal-T/S and Chlorphan 48% on the pink corn borer Sesamia cretica Led.

The aim of this study was to investigate influence of transgenic and commercial corn hybrids on the behaviour and feeding activity of the pink corn borer (Sesamia cretica Led.). Food consumption was different according to feeding period and hybrids. The feeding ratio of S. cretica on maize hybrids was significantly different between transgenic and commercial hybrids. It appears from the results of this experiment that the antifeeeding activity of transgenic hybrids had greater effect than commercial hybrids one. Thus, it is apparent from these results that transgenic maize was unsuitable because larvae were dead, but the other commercial hybrids were preferable. It can be concluded from the data that the feeding on different maize hybrids had different effects on certain biological aspects of pink corn borer. The impact of untreated Bt. Corn; 0.5% water emulsion of Neem-Azal-T/S and 0.005% water emulsion of Chlorpyrifos insecticides on the behaviour and feeding activity of the pink corn borer S. cretica has been studied. The data showed that larvae stopped feeding from the time when it was fed on untreated Bt. corn or/and non Bt. Corn treated with NeemAzal-T/S 0.5%. The results indicated that Bt. corn, NeemAzal-T/S 0.5% and Chlorphan 48% (0.005%) possessed the toxic effect on pink corn borer S. cretica. According to results, it could be stated that the tested compounds can play an important role in controlling the pink corn borer.     

Distribution of Field Corn Roots and Parasitic Nematodes in Subsoiled and Nonsubsoiled Soil

A field trial was conducted for 2 years in an Arredondo fine sand containing a tillage pan at 15-20 cm deep to determine the influence of subsoiling on the distribution of corn roots and plant-parasitic nematodes. Soil samples were taken at various depths and row positions at 30, 60, and 90 days after planting in field corn subsoiled under the row with two chisels and in non-subsoiled corn. At 30 and 60 days, in-row nematode population densities to 60 cm deep were not affected by subsoiling compared with population densities in nonsubsoiled plots. After 90 days, subsoiling had not affected total root length or root weight at the 20 depth-row position sampling combinations, but population densities of Meloidogyne incognita and Criconemella spp. had increased in subsoiled corn. Numbers of Pratylenchus zeae were not affected. Subsoiling generally resulted in a change in distribution of corn roots and nematodes in the soil profile but caused little total increase in either roots or numbers of nematodes. Corn yield was increased by subsoiling.     

不同微生物菌剂对基质酶活性和番茄产量及品质的影响

以鸡粪配方基质(腐熟鸡粪:腐熟玉米秸秆:河沙体积为3:4:3)和牛粪配方基质(腐熟牛粪:腐熟玉米秸秆:河沙体积为3:4:3)为试材,研究了基质中分别添加地福来、酵素菌、EM菌、枯草芽孢杆菌和农用微生物菌剂对基质酶活性和番茄产量及品质的影响.结果表明: 两种配方基质添加微生物菌剂40和60 d时根际基质的脲酶、蔗糖酶和碱性磷酸酶活性均显著提高,番茄植株生长量、果实产量及维生素C含量显著高于对照.鸡粪和牛粪配方基质均以添加地福来效果最好,番茄单株产量分别较各自对照增加14.7%和40.0%,果实维生素C含量分别提高22.2%和39.7%.在不添加微生物菌剂的情况下,鸡粪配方基质栽培的番茄单株产量和果实维生素C含量高于牛粪配方基质;分别添加地福来后,两种基质栽培的番茄单株产量和果实维生素C含量无显著差异.     

Biological hydrogen production by the algal biomass Chlorella vulgaris MSU 01 strain isolated from pond sediment

Chlorella vulgaris MSU 01 strain isolated from the sediment of the pond is able to produce molecular hydrogen in a clean way. To relate the dynamic coupling between the cultural conditions and biological responses, an original lab scale set up has been developed for hydrogen production. Different sources like mannitol, glucose, alanine, citric acid, aspartic acid, l-alanine, l-cysteine, sodium succinate and sodium pyruvate were used for algal media optimization. Corn stalk, from 1 to 5 g/L was tested for the effective algal growth and hydrogen production. The cell concentration of 1.6-19 g/L dry cell weight (DCW) was found at the 10th day. The kinetic parameters involved in the hydrogen production at 4 g/L corn stalk using the algal inoculum (50 mL) in the bioreactor volume (500 mL) was found to be with the hydrogen production potential (P_s) of 7.784 mL and production yield of (P_r) 5.534 mL respectively. The growth profile of the algal biomass at the above mentioned condition expressed the logistic model with R² 0.9988. The final pH of the broth was increased from 7.0 to 8.5-8.7. The anaerobic fermentation by C. vulgaris MSU 01 strain involved in the conversion process of complex carbon source has increased the H₂ evolution rate and higher butyrate concentration in the fermentate.     

Changes in plant cell-wall structure of corn stover due to hot compressed water pretreatment and enhanced enzymatic hydrolysis

Corn stover is a potential feedstock for biofuel production. This work investigated physical and chemical changes in plant cell-wall structure of corn stover due to hot compressed water (HCW) pretreatment at 170–190 °C in a tube reactor. Chemical composition analysis showed the soluble hemicellulose content increased with pretreatment temperature, whereas the hemicellulose content decreased from 29 to 7 % in pretreated solids. Scanning electron microscopy revealed the parenchyma-type second cell-wall structure of the plant was almost completely removed at 185 °C, and the sclerenchyma-type second cell wall was greatly damaged upon addition of 5 mmol/L ammonium sulfate during HCW pretreatment. These changes favored accessibility for enzymatic action. Enzyme saccharification of solids by optimized pretreatment with HCW at 185 °C resulted in an enzymatic hydrolysis yield of 87 %, an enhancement of 77 % compared to the yield from untreated corn stover.     

Bahiagrass,Corn, Cotton Rotations,and Pesticides for Managing Nematodes,Diseases, and Insects on Peanut

Florunner peanut was grown after 1 and 2 years of Tifton 9 bahiagrass, corn, cotton, and continuous peanut as whole-plots. Pesticide treatments aldicarb (3.4 kg a.i./ha), flutolanil (1.7 kg a.i./ha), aldicarb + flutolanil, and untreated (control) were sub-plots. Numbers of Meloidogyne arenaria second-stage juveniles in the soil and root-gall indices of peanut at harvest were consistently lower in plots treated with aldicarb and aldicarb + flutolanil than in flutolanil-treated and untreated plots. Percentages of peanut leaflets damaged by thrips and leafhoppers were consistently greater in flutolaniltreated and untreated plots than in plots treated with aldicarb or aldicarb + flutolanil but not affected by cropping sequences. Incidence of southern stem rot was moderate to high for all chemical treatments except those that included flutolanil. Stem rot loci were low in peanut following 2 years of bahiagrass, intermediate following 2 years of corn or cotton, and highest in continuous peanut. Rhizoctonia limb rot was more severe in the peanut monoculture than in peanut following 2 years of bahiagrass, corn, or cotton. Flutolanil alone or combined with aldicarb suppressed limb rot compared with aldicarb-treated and untreated plots. Peanut pod yields were 4,186 kg/ha from aldicarb + flutolanil-treated plots, 3,627 kg/ha from aldicarb-treated plots, 3,426 kg/ha from flutolanil-treated plots, and 3,056 kg/ha from untreated plots. Yields of peanut following 2 years of bahiagrass, corn, and cotton were 29% to 33% higher than yield of monocultured peanut.     

Performance of transgenic corn hybrids in Missouri for insect control and yield

The efficacy of Bacillus thuringiensis-transformed corn (Zea mays L.) hybrids compared with comparable nontransformed corn hybrids for controlling first- and second-generation European corn borer, Ostrinia nubilalis (Hübner), and second-generation southwestern corn borer, Diatraea grandiosella Dyar, was determined. Yield comparisons were obtained from the same plots of corn hybrids. Both generations of European and the second-generation of southwestern corn borer were effectively controlled, but the Bt hybrids varied in degree of control. Hybrids from Ciba Seeds, DEKALB, and Mycogen had more European corn borer tunneling than those from Novartis or Cargill, and this was generally ascribed to different transgenic events. The Bt-transformed hybrids had virtually no leaf-feeding damage and less tunneling than the non-Bt corn hybrids. Some Bt corn hybrids had no tunneling, whereas other Bt hybrids had a small amount of tunneling. All of the non-Bt hybrids had significant leaf-feeding damage and stalk tunneling from both insects. Only three live European corn borer larvae (stunted) were found in the Bt corn hybrids while splitting stalks to assess tunnel length. When insect damage was significant, and in some evaluations where damage was not significant, differences in yields among hybrids were observed. No significant insect population differences were observed for five genera of beneficial insects for Bt versus non-Bt corn hybrids. Corn hybrids that have been transformed with the Bt gene provide an effective means of control for corn borers and efforts to reduce the likelihood of development of borer resistance are warranted.     

Antioxidative effects of hesperetin against 7,12-dimethylbenz(a)anthracene-induced oxidative stress in mice

We investigated the effects of the chronic administration of hesperetin on the activation of the antioxidant defence system in mice in which oxidative stress had been induced by 7,12-dimethylbenz(a)anthracene (DMBA). Mice were divided randomly into three treatment groups. Hesperetin was administered orally to two of the three groups at 10 and 50 mg/kg body weight for 5 weeks. Subsequently, each group was subdivided randomly into DMBA-treated and untreated groups. The DMBA-treated groups were intragastrically administered a dose of 34 mg/kg BW in corn oil vehicle twice a week for 2 weeks. The TBARS value showed a tendency to decrease following hesperetin treatment; these decreases were significantly greater in the DMBA-treated than the untreated groups. Hesperetin significantly decreased the carbonyl content at the high dose in both DMBA-treated and untreated mice. Catalase and SOD activity were increased by hesperetin; this increase was more pronounced in DMBA-treated than untreated mice. Catalase, Mn-SOD, and CuZn-SOD expression analyses supported these results. Although the GSH-px and GR activity were little affected, hesperetin treatment significantly increased the GSH/GSSG ratio in the DMBA-treated group in a dose-dependent manner. These results suggest that hesperetin shows antioxidant activity and plays a protective role against DMBA-induced oxidative stress.