Effect of different supplements on bioprocessing of wheat straw by Phlebia brevispora: changes in its chemical composition, in vitro digestibility and nutritional properties

Bioprocessing of wheat straw was carried out by Phlebia brevispora under solid state conditions. Effect of different supplements on lignocellulolytic enzymes production, degradation of straw cell wall fibers and its resultant effect on nutritional quality of wheat straw were studied. Ammonium chloride and malt extract were more effective in terms of ligninolysis and enhanced in vitro digestibility. The concentration of the selected supplements and the moisture content was worked out using response surface methodology in order to minimize the loss in total organic matter so as to selectively degrade lignin. The experiment was scaled up to batches of 200 g under optimized conditions and the degraded substrate was analyzed for its biochemical properties. P. brevispora degraded 290 g/kg of lignin and enhanced the in vitro digestibility from 150 to 268 g/kg (78%). Crude protein, amino acids, total phenolic contents and antioxidant properties were significantly higher in degraded straw.     

Effect of biodelignification of rice straw on humification and humus quality by Phanerochaete chrysosporium and Streptomyces badius

The effect of biodelignification of rice straw by two different ligninolytic organisms, Phanerochaete chrysosporium (white-rot fungus) and Streptomyces badius (actinomycetes), on humus quality was investigated during a 56-day incubation at 30 °C. Lignin degradation, the release of humic extract (HE), humic acid (HA) and fulvic acid (FA), E4/E6 ratio of HA, and humification index (HI, HA/FA) were measured during the incubation. Lignin was degraded by both organisms, but to different extents. Lignin was degraded to 41% and 31% by P. chrysosporium and S. badius, respectively. HE released by P. chrysosporium and S. badius were, respectively, 2.10 and 2.13 times larger than that in the control at the maximum values. A significant correlation between lignin degradation and humus-related parameters involving HA fraction showed that both organisms are converting lignin to humic substances.     

Chemical and biological properties of wheat soil in response to paddy straw incorporation and its biodegradation by fungal inoculants

A field experiment was conducted to evaluate the relative contribution of organic fertilizers (paddy straw, microbial inoculants and vermicompost) and inorganic fertilizers (urea and superphosphate) in improving pH, C, N, humus, microbial biomass, dehydrogenase, phosphatase, cellulase, β-glucosidase and xylanase activities of soil under wheat crop. Vermicompost fertilization resulted in highest microbial biomass, available phosphorus, and nitrogen content of wheat soil. It was also found effective in minimizing the alkalinity of soil compared to other treatments as indicated by pH change. However incorporation of paddy straw in conjunction with N₆₀P₆₀ and T. reesei inoculation resulted in maximum dehydrogenase, alkaline phosphatase and highest humus content of soil. Mixed inoculation of A. awamori and T. reesei did not prove effective in improving the soil biochemical properties in comparison to single inoculation of T. reesei. Results showed that in situ incorporation of paddy straw in combination with N₆₀P₆₀ and T. reesei inoculation can be used as an effective measure for valuable disposal of paddy straw and to improve the soil health by reducing mineral fertilization.     

Phylogeographic patterns in Leccinum sect. Scabra and the status of the arctic-alpine species L. rotundifoliae

We investigated inter- and intraspecific phylogenetic relationships in the ectomycorrhizal fungal genus Leccinum section Scabra. Species of this section are exclusively associated with Betula and occur throughout the Northern Hemisphere. We compared the phylogenetic relationships of arctic, alpine, boreal and temperate accessions of section Scabra based on DNA sequences of the single-copy nuclear gene Gapdh and the multiple-copy nuclear region 5.8S-ITS2. Exclusively arctic lineages were not detected in species that occur both in arctic-alpine or boreal regions, except in L. rotundifoliae that was restricted to cold climates. L. scabrum and L. holopus showed an intercontinental phylogeographic pattern, and L. variicolor showed a pattern unrelated to geographical distribution. Molecular clock estimates indicated that L. rotundifoliae is as old as other species in section Scabra. Individual gene trees suggest that interspecific hybridisation occurred several times in the evolution of section Scabra.     

Intracellular degradation of two structurally different polyhydroxyalkanoic acids accumulated in Pseudomonas putida and Pseudomonas citronellolis from mixtures of octanoic acid and 5-phenylvaleric acid

From a set of mixed carbon sources, 5-phenylvaleric acid (PV) and octanoic acid (OA), polyhydroxyalkanoic acid (PHA) was separately accumulated in the two pseudomonads Pseudomonas putida BM01 and Pseudomonas citronellolis (ATCC 13674) to investigate any structural difference between the two PHA accumulated under a similar culture condition using one-step culture technique. The resulting polymers were isolated by chloroform solvent extraction and characterized by fractional precipitation and differential scanning calorimetry. The solvent fractionation analysis showed that the PHA synthesized by P. putida was separated into two fractions, 3-hydroxy-5-phenylvalerate (3HPV))-rich PHA fraction in the precipitate phase and 3-hydroxyoctanoate (3HO)-rich PHA fraction in the solution phase whereas the PHA produced by P. citronellolis exhibited a rather little compositional separation into the two phases. According to the thermal analysis, the P. putida PHA exhibited two glass transitions indicative of the PHA not being homogeneous whereas the P. citronellolis PHA exhibited only one glass transition. It was found that the structural heterogeneity of the P. putida PHA was caused by a significant difference in the assimilation rate between PV and OA. The structural heterogeneity present in the P. putida PHA was also confirmed by a first order degradation kinetics analysis of the PHA in the cells. The two different first-order degradation rate constants (k₁), 0.087 and 0.015/h for 3HO- and 3HPV-unit, respectively, were observed in a polymer system over the first 20 h of degradation. In the later degradation period, the disappearance rate of 3HO-unit was calculated to be 0.020 h. The k₁ value of 0.083/h, almost the same as for the 3HO-unit in the P. putida PHA, was obtained for the P(3HO) accumulated in P. putida BM01 grown on OA as the only carbon source. In addition, the k₁ value of 0.015/h for the 3HPV-unit in the P. putida PHA, was also close to 0.019/h for the P(3HPV) homopolymer accumulated in P. putida BM01 grown on PV plus butyric acid. On the contrary, the k₁ values for the P. citronellolis PHA were determined to be 0.035 and 0.029/h for 3HO- and 3HPV-unit, respectively, thus these two relatively close values implying a random copolymer nature of the P. citronellolis PHA. In addition, the faster degradation of P(3HO) than P(3HPV) by the intracellular P. putida PHA depolymerase indicates that the enzyme is more specific against the aliphatic PHA than the aromatic PHA.     

微泡菌属菌株YPW1和YPW16多糖降解特性分析

【背景】海洋环境中分离到的微泡菌属菌株具有多糖降解能力,在环境中可以作为糖类代谢的重要执行者参与海洋碳循环过程。【目的】测定2株微泡菌属菌株的多糖降解活性,通过与微泡菌属其他菌株基因组比较分析2株菌的多糖降解基因特征。【方法】通过3,5-dinitrosalicylicacid(DNS)定糖法测定多糖降解活性,同时利用高通量测序技术对菌株基因组序列进行测定与组装,并与其他基因组注释结果进行比较分析。【结果】分离得到2株微泡菌属菌株YPW1和YPW16,二者均为潜在新种。结果表明,菌株YPW1能够降解琼胶、褐藻胶、果胶、几丁质、木聚糖、淀粉、普鲁兰等7种多糖,而菌株YPW16仅可降解淀粉和普鲁兰。基因组分析表明,YPW1具有上述7种多糖的降解酶基因,但菌株YPW16只具有淀粉酶与普鲁兰酶降解基因。相较于其他微泡菌属菌株,菌株YPW1多糖降解范围、多糖降解酶基因种类与丰度较高,但菌株YPW16多糖降解范围却较为狭窄。由此可知,多糖降解酶基因在微泡菌属基因组中的分布差异性较大。【结论】本研究为微泡菌属提供了2株潜在的新型菌株资源,为生物多糖降解提供了生化工具,也为研究微泡菌属菌株中多糖降解基...     

Topochemical investigation of early stages of lignin modification within individual cell wall layers of Scots pine (Pinus sylvestris L.) sapwood infected by the brown-rot fungus Antrodia vaillantii (DC.: Fr.) Ryv.

The initiation and progress of wood degradation of Pinus sylvestris sapwood exposed to the brown-rot fungus Antrodia vaillantii was studied on a cellular level by scanning UV microspectrophotometry (UMSP 80, Zeiss, MSP 800 Spectralytics). This improved analytical technique enables direct imaging of lignin modification within individual cell wall layers. The topochemical analyses were supplemented by light and transmission electron microscopy (TEM) studies in order to characterize morphological changes during the first days of degradation. Small wood blocks (1.5 × 1.5 × 5 mm) of Scots pine (P. sylvestris) were exposed to fungal decay by A. vaillantii for 3, 7, 11, 16, and 22 days. No significant weight loss was determined in the initial decay periods within three up to 7 days. After three days of decay the topochemical investigation revealed that the lignin modification starts at the outermost part of the secondary wall layer, especially in the region of the latewood tracheids. During advanced degradation after exposure of 22 days, lignin modification occurs non-homogeneously throughout the tissue. Even among the significantly damaged cells, some apparently unmodified cells still exist. Knowledge about lignin modification at initial stages of wood degradation is of fundamental importance to provide more information on the progress of brown-rot decay.     

A C CP/MAS NMR evaluation of the structural changes in wheat straw subjected to different chemical and biological pulping conditions

Wheat straw pulps prepared by chemical (soda) and biological (enzymatic or fungal) treatments were analyzed by ¹³C CP/MAS NMR spectrometry under quantitative acquisition conditions. The most significant changes reflected in the spectra as a result of soda cooking correspond to: (i) decrease of methoxyl content of the residual lignin (56, 153, 147 and 135 ppm), and (ii) deacetylation of hemicellulose fractions and saponification of cinnamyl esters concomitant to the release of alkali-soluble fractions (21 and 172 ppm). Reaction time was the factor with the greatest bearing on the former process, whereas soda concentration and temperature play an additional role in the latter. The decrease of the methoxyl/aryl ratio both after chemical and biological pulping suggests preferential removal of S-type lignin units. The comparison between quality parameters of the pulps and the ¹³C NMR integration data suggests that the linkage breakdown between straw macromolecules has a greater influence on paperboard properties than the neat extent of the chemical and biological removal of lignin fractions.     

丁酸梭菌发酵培养基的优化及发酵产物对黄曲霉毒素B1的降解

【背景】丁酸梭菌是专性厌氧的新一代芽孢益生菌,耐热、耐酸、抗逆性强,极具应用价值和开发前景。【目的】优化丁酸梭菌发酵培养基并初步研究其发酵液对黄曲霉菌的抑制作用和降解黄曲霉毒素B₁ (aflatoxin B₁, AFB₁)的能力。【方法】利用响应面法对发酵培养基进行优化,采用牛津杯法对丁酸梭菌发酵液抑制黄曲霉菌生长进行研究,并通过酶联免疫法测定发酵液对AFB₁的降解能力。【结果】优化后的发酵培养基为：葡萄糖18.1g/L,大豆蛋白胨29.7g/L,磷酸氢二钾3.8 g/L,氯化钠2.0 g/L,乙酸钠4.0 g/L,结晶硫酸镁1.2 g/L,L-半胱氨酸盐酸盐0.3 g/L。优化后的丁酸梭菌生物量由8.99×10⁸个/mL提高至2.28×10⁹个/mL,是优化前的2.54倍。丁酸梭菌发酵液对致病真菌黄曲霉菌的抑菌效果十分显著,其上清液经浓缩后对AFB₁降解72h的降解率达到68.65%,初步分析表明上清液中对AFB₁     

大麦虫及其肠道微生物对聚乙烯的生物降解

【背景】废旧塑料聚乙烯因具有较高的化学惰性,不易被自然降解而形成长期污染。【目的】探究聚乙烯泡沫塑料对大麦虫生长发育的影响,为大麦虫作为降解聚乙烯泡沫塑料的昆虫推广提供理论依据。【方法】以大麦虫幼虫为研究对象,选用常见的泡沫塑料(聚乙烯),采用4种不同的饲喂方式T1 (麦麸)、T2 (泡沫塑料)、T3 (泡沫塑料+麦麸)、T4 (不饲喂)进行驯化,处理30 d后对大麦虫进行解剖,取肠道内容物于LB培养基中进行富集培养,将富集培养后的菌液加入以聚乙烯(polyethylene,PE)为唯一碳源的LCFBM培养基进行选择性培养,从中筛选分离得到对PE塑料有降解能力的菌株。【结果】取食泡沫塑料30d后,与单一饲喂PE相比,麦麸和PE混合饲喂后大麦虫幼虫的存活率为76%。采用傅里叶变换红外光谱检测发现虫粪组分中主要官能团中峰值明显变化,表明PE长链有断裂现象,并从肠道中分离得到3株可以对PE薄膜边缘造成明显侵蚀的菌株。【结论】大麦虫可取食并消化PE塑料,其肠道内的微生物对PE塑料的降解起到关键作用,研究结果为塑料污染的生物降解提供了科学证据。     

结冷胶固定化保加利亚乳杆菌及在玉米秸秆连续发酵d-乳酸中的应用

秸秆生物炼制化学品是解决秸秆资源利用附加值低、减轻秸秆焚烧带来的环境污染的主要方法之一。本研究制备了结冷胶固定化保加利亚乳酸杆菌(Lactobacillus bulgaricus)T15凝胶珠(结冷胶-T15凝胶珠),并对其性质进行表征,建立了结冷胶-T15凝胶珠固定化细胞循环连续发酵产D-乳酸发酵工艺。结冷胶-T15凝胶珠的断裂应力为(91.68±0.11) kPa,较海藻酸钙固定化T15凝胶珠(海藻酸钙-T15凝胶珠)提高了125.12%,表明结冷胶-T15凝胶珠的强度更强。以结冷胶-T15凝胶珠为出发菌株,葡萄糖为发酵基质,10批次循环(720h)发酵,其D-乳酸最高批次产量为(72.90±2.79)g/L,较海藻酸钙-T15凝胶珠提高了33.85%,较游离T15提高了37.70%。将葡萄糖更换为玉米秸秆酶解液,使用结冷胶-T15凝胶珠进行10批次循环(240 h)发酵,D-乳酸生产强度可达(1.74±0.79)g/(L·h),远高于游离菌。10批次循环发酵后结冷胶-T15凝胶珠磨损率小于5%,表明结冷胶是一种细胞固定化的良好载体,可广泛应用于细胞固定化工业发酵领域。本研究为细胞...     

Phenotypic suppression of the Drosophila mitochondrial disease-like mutant tko by duplication of the mutant gene in its natural chromosomal context

A mutation in the Drosophila gene technical knockout (tko^25t), encoding mitoribosomal protein S12, phenocopies human mitochondrial disease. We isolated three spontaneous X-dominant suppressors of tko^25t (designated Weeble), exhibiting almost wild-type phenotype and containing overlapping segmental duplications including the mutant allele, plus a second mitoribosomal protein gene, mRpL14. Ectopic, expressed copies of tko^25t and mRpL14 conferred no phenotypic suppression. When placed over a null allele of tko, Weeble retained the mutant phenotype, even in the presence of additional transgenic copies of tko^25t. Increased mutant gene dosage can thus compensate the mutant phenotype, but only when located in its normal chromosomal context.     

一株尼古丁降解菌株Arthrobacter sp.D4的分离鉴定及其降解代谢途径

【背景】烟草在生产和加工中会产生高浓度的尼古丁废弃物,对环境造成较大的污染。【目的】筛选降解尼古丁的微生物菌种并解析其降解尼古丁的代谢途径,理解微生物如何降解尼古丁。【方法】用常规分离筛选方法、结合形态学观察和分子鉴定手段分离和鉴定菌株类别,进而利用单因素试验方法,通过设置不同的尼古丁浓度、温度和pH确定菌株降解尼古丁的最适发酵条件和降解率,利用气相色谱-质谱联用技术检测菌株在尼古丁降解过程中的主要代谢产物。【结果】获得一株以尼古丁为唯一碳源和氮源的节杆菌属(Arthrobacter)菌株,编号为D4;该菌株降解尼古丁的最适温度和pH分别为30.0℃和7.0;在1 g/L的尼古丁浓度下具备较快的尼古丁降解速率,培养18 h时尼古丁降解率可达到90%以上;尼古丁浓度≥4 g/L时菌株生长受到明显抑制;与目前报道的节杆菌属降解途径不同,该菌株降解尼古丁过程中产生了新的终产物N-甲基吡咯烷酮、可替宁及中间产物麦斯明。【结论】本研究分离鉴定到一株具有较快尼古丁降解速率的节杆菌,该菌株很可能存在新的尼古丁降解途径。     

Role of veratryl alcohol in lignin degradation by Phanerochaete chrysosporium

Several aromatic compounds increased initial lignin degradation rates in cultures of Phanerochaete chrysosporium. This activation was connected to increased H₂O₂ production and glucose oxidation rates. Veratryl alcohol, a natural secondary metabolite of P. chrysosporium, also activated the lignin-degrading system. In the presence of added veratryl alcohol the ligninolytic system appeared 6–8 h earlier than in reference cultures. This effect was only seen when lignin was added after the primary growth was completed because lignin itself also caused earlier appearance of the degradative system. In cultures which received no added lignin or veratryl alcohol the ligninolytic activity only appeared once the alcohol started to accumulate. The degradation patterns of veratryl alcohol and lignin were similar. The activity levels of lignin degradation and glucose oxidation could be regulated by veratryl alcohol concentration. It is suggested that either veratryl alcohol itself or a metabolite derived from it is actually responsible for the low levels of ligninolytic activity in glucose grown cultures.     

Effects of different Beauveria bassiana isolates on field populations of Lygus lineolaris in pigweed (Amaranthus spp.)

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is a pest of various fruit, vegetable, fiber, and seed crops; including cotton. Lygus spp. populations often build on alternate host plants before moving to cotton, and in the midsouthern U.S. wild host plants, such as pigweed (Amaranthus spp.), play a major role in L. lineolaris population development. Three isolates of the entomopathogenic fungus Beauveria bassiana (Balsamo) were evaluated for L. lineolaris control in redroot pigweed (Amaranthus retroflexus L.): one from L. lineolaris in Mississippi (TPB3); one from Lygus hesperus (Knight) in California (WTPB2); and one commercial isolate from Mycotrol^® (GHA). Fungal applications resulted in moderate to high mycosis in adults (33 to 80%) and moderate mycosis in nymphs (36 to 53%) that were collected from field plots at 2 days post-treatment and incubated under laboratory conditions. Although TPB3 was previously found to be more pathogenic in laboratory bioassays, there was not a consistent separation of this isolate from the other two isolates in field trials. Where differences in adult mycosis or mortality were observed, TPB3 was the most pathogenic. However, in one field trial 7 day mortality for nymphs treated with GHA was higher than those treated with TPB3 or WTPB2. Infection rates at 2, 7, and 14 days post-treatment from caged and non-caged adults suggested that movement of adults among plots occurred, which could have masked some treatment effects. Fungal treatments did not significantly reduce populations relative to controls. This may have been caused by delayed mortality rates under field conditions and/or difficulties with estimating population change under field conditions characteristic of wild host plant populations (e.g., heterogeneous populations, adult movement, and small plot size). Further work evaluating time–dose–mortality over dynamic temperatures, spring and fall field trials on this and other wild hosts, and improved methods for estimating populations on wild hosts are needed.     

Elimination of EVE protein by CALI in the short germ band insect Tribolium suggests a conserved pair-rule function for even skipped

The question of the degree of evolutionary conservation of the pair-rule patterning mechanism known from Drosophila is still contentious. We have employed chromophore-assisted laser inactivation (CALI) to inactivate the function of the pair-rule gene even skipped (eve) in the short germ embryo of the flour beetle Tribolium. We show that it is possible to generate pair-rule type phenocopies with defects in alternating segments. Interestingly, we find the defects in odd numbered segments and not in even numbered ones as in Drosophila. However, this apparent discrepancy can be explained if one takes into account that the primary action of eve is at the level of parasegments and that different cuticular markers are used for defining the segment borders in the two species. In this light, we find that eve appears to be required for the formation of the anterior borders of the same odd numbered parasegments in both species. We conclude that the primary function of eve as a pair rule gene is conserved between the two species.     

Diet and physiological responses of Spondyliosoma cantharus (Linnaeus, 1758) to the Caulerpa racemosa var. cylindracea invasion

Marine invasions are a worldwide problem that involves changes in communities and the acclimation of organisms to them. The invasive Chlorophyte Caulerpa racemosa var. cylindracea is widespread in the Mediterranean and colonises large areas from 0 to 70 m in depth. The omnivorous fish Spondyliosoma cantharus presents a high frequency of occurrence of C. racemosa in the stomach contents at invaded areas (76.3%) while no presence of C. racemosa was detected in control areas. The isotopic composition of muscle differed significantly between invaded and non-invaded sites for δ¹³C (− 16.67‰ ± 0.09 and − 17.67‰ ± 0.08, respectively), δ¹⁵N (10.22‰ ± 0.22 and 9.32‰ ± 0.18, respectively) and the C:N ratio (2.01 ± 0.0002 and 1.96 ± 0.009, respectively). Despite the high frequency of occurrence of C. racemosa in the stomach contents of S. cantharus and its important contribution to the δ¹³C source (20.7% ± 16.2), the contribution of C. racemosa to the δ¹⁵N in S. cantharus food sources was very low (6.6% ± 5.8). Other invertebrate prey such as decapods and polychaetes were more important contributors to the δ¹⁵N source at both invaded and non-invaded sites. Activation of enzymatic pathways (catalase, superoxide dismutase, glutathione-s-tranferase, 7-ethoxy resorufin O-de-ethylase) but not a significant increase in lipid peroxidation MDA (0.49 ± 0.01 nmol/mg prot at non-invaded and 0.53 ± 0.01 nmol/mg prot at invaded sites) was observed in S. cantharus individuals living in C. racemosa-invaded sites compared with control specimens. The low δ¹⁵N contribution values of C. racemosa by S. cantharus together with the toxicity demonstrated by the activation of the antioxidant defences and the important contribution of invertebrate prey to the δ¹⁵N could mean that the ingestion of C. racemosa by S. cantharus might be unintentional during the predation of invertebrate preys living underneath the entanglement of the C. racemosa fronds and stolons mats.     

Influence of aFusarium culmorum inoculation of wheat onin sacco dry matter degradation of wheat straw and wheat chaff

The aim of this study was to investigate the effect of aFusarium culmorum inoculation of wheat on thein sacco dry matter degradation (DG) of wheat straw and wheat chaff in dairy cows. The ruminal disappearance of dry matter was measured with thein situ nylon bag technique. Samples of wheat straw and wheat chaff from non-inoculated andFusarium-inoculated wheat were used to examine the ruminal dry matter degradability. Samples were subjected to ruminal incubation in two dairy cous fitted with a permanent rumen fistula and incubated for 4, 8, 16, 24, 48, 72, 96 and 120 h. To describe the degradation kinetics, the equation by Ørskov and McDonald (1979) was used. DG rates obtained for contaminates straw and chaff were higher compared to the corresponding rates of the non-contaminated samples, which is assumed to be due to the activity of fungal enzymes. It can be concluded that an infection of wheat withF. culmorum may have an influence on the dry matter degradation of straw and chaff.