Microbiological contamination of pap ‘akamu’ in Bauchi markets from water or utensils?

Bacteriological qualities of water and utensils were determined in Bauchi in order to ascertain the potential routes and sources of contamination of pap samples prepared from maize and sold in three Bauchi markets. Eleven genera of bacteria were isolated in the pap samples. These included: Streptococci, Staphylococci, Neisseriae, Enterobacter, Lactobacilli, Klebsiella, Proteus, Citrobacter, Micrococcus, Leuconostoc and Bacillus. The water samples contained seven genera: Staphylococci, Enterobacter, Klebsiella, Proteus, Citrobacter, Escherichia coli and Shigella. Water was eliminated as the route and source of Strepotococci, Neisseriae, Lactobacter, Micrococcus, Leuconostoc and Bacillus found in pap. The utensils contained six genera: Streptococci, Enterobacter, Lactobacilli, Klebsiella, Micrococcus and Bacillus. Utensils were eliminated as the potential route and source of Staphylococci, Neisseriae, Proteus, Citrobacter and Leuconostoc found in pap. The Shigella and Escherichia coli came from water alone. The mean bacteria counts varied with isolates. For example, pap was 10⁹ order, Yelwa water and utensils were 10² order each. However, each group of samples from the markets and among the markets showed no variability. The statistical analysis for the goodness of fit that there was no significant difference between the observed and the expected data was highly significant for all maize samples, most water samples and a few utensil counts at 99.9% level.     

Cry1Ie基因在大肠杆菌中的表达及等同性鉴定

目的以Cry1Ie基因表达蛋白为模式蛋白,建立外源基因表达蛋白的技术平台。方法利用大肠杆菌系统高效表达Cry1Ie蛋白,并采用SDS-PAGE技术分离纯化,通过生物学活性和免疫反应性2项指标检测了大肠杆菌表达蛋白与转基因玉米中蛋白的等同性。结果大肠杆菌表达系统可以产生大量的Cry1Ie蛋白,所获得的蛋白与转Cry1Ie玉米表达的Cry1Ie蛋白有相同的免疫反应性和生物活性。结论大肠杆菌表达系统可以作为Cry1Ie外源基因蛋白表达技术平台用于转基因植物食用安全性的初步研究。     

An alternative strategy for sustainable pest resistance in genetically enhanced crops

Bacillus thuringiensis (Bt) crystal protein genes encode insecticidal delta-endotoxins that are widely used for the development of insect-resistant crops. In this article, we describe an alternative transgenic strategy that has the potential to generate broader and more sustainable levels of resistance against insect pests. Our strategy involves engineering plants with a fusion protein combining the delta-endotoxin Cry1Ac with the galactose-binding domain of the nontoxic ricin B-chain (RB). This fusion, designated BtRB, provides the toxin with additional, binding domains, thus increasing the potential number of interactions at the molecular level in target insects. Transgenic rice and maize plants engineered to express the fusion protein were significantly more toxic in insect bioassays than those containing the Bt gene alone. They were also resistant to a wider range of insects, including important pests that are not normally susceptible to Bt toxins. The potential impact of fusion genes such as BtRB in terms of crop improvement, resistance sustainability, and biosafety is discussed.     

Multi-Mycotoxin Contamination of Maize Silages in Flanders,Belgium: Monitoring Mycotoxin Levels from Seed to Feed

Maize silage, which in Europe is the main feed for dairy cattle in winter, can be contaminated by mycotoxins. Mycotoxigenic Fusarium spp. originating from field infections may survive in badly sealed silages or re-infect at the cutting edge during feed-out. In this way, mycotoxins produced in the field may persist during the silage process. In addition, typical silage fungi such as Penicillium spp. and Aspergillus spp. survive in silage conditions and produce mycotoxins. In this research, 56 maize silages in Flanders were sampled over the course of three years (2016–2018). The concentration of 22 different mycotoxins was investigated using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, and the presence of DNA of three Fusarium spp. (F. graminearum, F. culmorum and F. verticillioides) was analyzed in a selection of these samples using quantitative polymerase chain reaction (qPCR). Every maize silage contained at least two different mycotoxins. Nivalenol (NIV) and deoxynivalenol (DON) were the most prevalent (both in 97.7% of maize silages), followed by ENN B (88.7%). Concentrations often exceeded the EU recommendations for DON and zearalenone (ZEN), especially in 2017 (21.3% and 27.7% of the maize silages, respectively). No correlations were found between fungal DNA and mycotoxin concentrations. Furthermore, by ensiling maize with a known mycotoxin load in a net bag, the mycotoxin contamination could be monitored from seed to feed. Analysis of these net bag samples revealed that the average concentration of all detected mycotoxins decreased after fermentation. We hypothesize that mycotoxins are eluted, degraded, or adsorbed during fermentation, but certain badly preserved silages are prone to additional mycotoxin production during the stable phase due to oxygen ingression, leading to extremely high toxin levels.     

Anti-fungal activity of maize silk proteins and role of chitinases in Aspergillus flavus resistance

Studies were conducted to identify proteins in maize silks that may be contributing to Aspergillus flavus resistance. We first performed bioassays using silk extracts collected from two A. flavus-resistant inbred lines and two susceptible inbred lines. Fungal biomass was quantified by measuring fluorescence of a green fluorescent protein (GFP)-tagged A. flavus and by measuring ergosterol levels. The silk extracts from resistant inbreds had greater anti-fungal activity compared to susceptible inbreds. Comparative proteomic analysis of the two resistant and susceptible inbreds led to the identification of several anti-fungal proteins. One of the anti-fungal proteins that we further investigated was chitinase. There were three chitinases that were differentially expressed in the resistant lines (PRm3 chitinase, chitinase I, and chitinase A). We conducted chitinase assays on silk proteins from extracts of resistant and susceptible inbred lines. Silk extracts from resistant inbred lines showed significantly higher activity in the resistant maize inbreds compared to the susceptible inbreds (P?<?0.01). The differential expression of chitinases in maize resistant and susceptible inbred silks suggests that these proteins may contribute to A. flavus resistance.     

SFE-GC/HPLC对重离子辐照育种的玉米油中五种营养物质的含量分析

目的分析重离子辐射育种的玉米油中棕榈酸、油酸、亚油酸、维生素E(VE)和β-胡萝卜素5种营养物质的含量变化。方法重离子辐照育种的玉米粒粉碎后利用CO2-SFE萃取技术进行玉米油的提取分离,然后利用GC色谱和HPLC色谱分别对棕榈酸、油酸和亚油酸及VE和β-胡萝卜素进行含量的检测分析。结果重离子辐照处理对玉米油中5种营养物质含量的积累具有正、负双重效应,对于多数辐照品种营养物质的含量基本呈现增加趋势,增加的范围分别为4.35%～18.39%、5.21%～28.73%、3.545%～12.18%、0.5587%～28.02%和7.621%～19.46%;但对于某些辐照品种,营养物质的积累也会表现为下降,比如,CSR24001的油酸含量相对于对照降低了7.21%,金象4C-1的VE含量相对于对照降低了14.52%;除CSR24001外,辐照后3种脂肪酸总量均有不同程度增加,其中,棕榈酸所占比例因品种差异而不同、油酸除CSR24001外均有所增加、亚油酸则均表现为下降。结论通过重离子辐照进行玉米诱变育种,可有效提高玉米油中营养物质含量,改变营养物质的比例,进而改进玉米籽粒的品质。     

玉米花粉黄酮类物质对SD大鼠降血脂作用的研究

目的：探讨玉米花粉黄酮灶物质对SD大鼠降血脂效应，为玉米花粉黄酮类物质做降血脂治疗提供依据。方法：用高脂高胆固醇饲料复制SD大鼠高脂血症动物模型，给予玉米黄酮类物质以观察其治疗高血脂症作用，玉米花粉黄酮类物质，分别按400gm/kg,200mg/kg,100mg/kg体重剂量灌有给药，20天后，观察给药动物和对照组血清甘油三酯（TG）和胆固醇（TG）的变化情况。结果：给患高血脂症的动物连续20天灌胃玉米动物和对照组血清甘油三酯（TG)胆固醇（TG）的变化情况。结果：给患高血脂症的动物连续20天灌胃玉米黄酮类物质后，其血清胆固醇和甘油三酯含量与模型对照相比，均有明显差异，在三种不同剂量中以中剂量（200mg/kg)组效果最为显著。结论：玉米黄酮类物质对实验性高脂血症和高胆固醇血症均有显著的治疗作用。     

不同收获期青贮玉米贮前和贮后营养含量变化研究

本文对乳熟前期、乳熟期和蜡熟期青贮玉米贮前和贮后主要营养成分进行了测试分析,结果表明：蜡熟期青贮玉米贮前和贮后的营养含量均高于乳熟前期和乳熟期,如蜡熟期青贮玉米贮前的DM（29.89%）分别比乳熟前期（23.17%）和乳熟期（23.17%）高6.72（P〈0.01）和4.72（P〈0.05）个百分点,乳熟期比乳熟前期高2个百分点（P〈0.05）;蜡熟期青贮玉米贮后的DM分别比乳熟前期和乳熟期高5.7（P〈0.01）和5.18（P〈0.01）个百分点.同一收获期的青贮玉米贮后营养物质含量有所降低,如乳熟前期、乳熟期和蜡熟期青贮玉米贮后DM均分别比贮前下降1.47（P〈0.05）、2.95（P〈0.05）和2.49（P〈0.05）个百分点。     

Mycotoxins in Maize Silage from China in 2019

Animal feed (including forage and silage) can be contaminated with mycotoxins. Here, 200 maize silage samples from around China were collected in 2019 and analyzed for regulated mycotoxins, masked mycotoxins (deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, and deoxynivalenol-3-glucoside), and emerging mycotoxins (beauvericin, enniatins, moniliformin, and alternariol). Deoxynivalenol and zearalenone were detected in 99.5% and 79.5% of the samples, respectively. Other regulated mycotoxins were detected in fewer samples. The highest deoxynivalenol and zearalenone concentrations were 3600 and 830 μg/kg, respectively. The most commonly detected masked mycotoxin was 15-acetyldeoxynivalenol, which was detected in 68.5% of the samples and had median and maximum concentrations of 61.3 and 410 μg/kg, respectively. The emerging mycotoxins beauvericin, alternariol, enniatin A, enniatin B1, and moniliformin were detected in 99.5%, 85%, 80.5%, 72.5%, and 44.5%, respectively, of the samples but at low concentrations (medians <25 μg/kg). The samples tended to contain multiple mycotoxins, e.g., the correlation coefficients for the relationships between the concentrations of beauvericin and deoxynivalenol, deoxynivalenol and zearalenone, and zearalenone and beauvericin were 1.0, 0.995, and 0.995, respectively. The results indicated that there needs to be more awareness of the presence of one or more masked and emerging mycotoxins in maize silage in China.