发酵饲料对猪肉品质的影响及应用研究进展

发酵饲料作为一种新型绿色环保的功能性饲料,具有提高饲料营养价值、降低抗营养因子含量、改善饲料适口性、有益动物肠道健康、促进动物生长发育、改善动物产品质量和减排环保等特点.文章对发酵饲料的定义和益处进行了简要的概述,重点讨论了其对猪肉品质的影响、机理和其在猪肉生产上的应用,以期为发酵饲料的合理开发与高效应用提供参考.     

食品微生物快速检测技术研究进展

近年来,微生物及其产生的各类毒素引发的食品污染备受重视,微生物污染造成的食源性疾病仍是世界食品安全中最突出的问题。准确、省时的快速检验方法,对预防肠道传染病和食物中毒具有重要意义。随着生物学技术和微电子技术的发展,食品微生物快速检验技术有了较大进展。综述了食品微生物快速检验技术的研究进展。     

青贮饲料中微生物及乳酸菌特性初步研究

分析青贮饲料中微生物的种类和数量,从中分离鉴定了22株乳酸菌,并研究了这些乳酸菌的特性。结果表明:分离株都是革兰氏阳性、过氧化氢酶阴性和兼性厌氧菌。根据所分离到的乳酸菌的形态学和生理生化特性,这些乳酸菌可被分为6组(A-F)。经表型分类鉴定,A组、B组、C组和D组为典型的乳杆菌属(Lactobacillus)。E组属于肠球菌属(Enterococcus)。F组为明串珠菌属(Leuconostoc)。青贮饲料中的大多数乳酸菌为乳杆菌属(Lactobacillus),占总数的79%以上。     

Biomanagement of Fusarium wilt of tomato by the soil application of certain phosphatesolubilizing microorganisms

Abstract

We tested whether a new automated bait dispenser, the Scentinel®, could be programmed to deliver non-toxic bait selectively only to animals of specified dimensions (>400 g body weight and <110 mm body diameter, the size of a ferret or a mink). We tested whether wild ferrets would discriminate between two types of bait (egg/oil and homogenised brain tissue). We set 24 Scentinels in 12 randomised pairs for 11 weeks on a 2400-ha area of pastoral farmland in New Zealand. Of 1559 visits by small animals, 198 were by ferrets (c. 28 individuals). The Scentinels correctly delivered 895 baits to visitors weighing >400 g, and no baits to 543 visitors of <400 g. The mean body weight of live ferrets recorded by Scentinels was not significantly different from that of 34 carcasses collected from the same area by professional trappers. Of the 145 baits dispensed to ferrets, egg/oil bait was significantly more often eaten. We conclude that the Scentinel can reliably deliver bait to specified sizes of animals and deny it to others. It can also facilitate extensive bait preference tests on unrestrained wild pests.     

Direct and indirect effects of tree diversity drive soil microbial diversity in temperate deciduous forest

We investigated the link between aboveground and belowground diversity in temperate deciduous forest ecosystems. To this end, we determined the effects of the tree species composition on the biomass and composition of the soil microbial community using phospholipid fatty acid (PLFA) profiles in the Hainich National Park, a deciduous mixed forest on loess over limestone in Central-Germany. We investigated the effects of the leaf litter composition on the microbial community, hypothesizing that distinctive leaf litter compositions increase signature PLFAs. In addition, we studied the impact of clay content, pH and nutrient status of the soil on the microbial community in different surface soil layers. Consequently, soil was sampled from depths of 0-5 cm, 5-10 cm and 10-20 cm. Plots with highest leaf litter diversity had the largest total amounts of fatty acids, but only PLFA 16:1ω5, which is a common marker for arbuscular mycorrhizal fungi, was significantly increased. In the uppermost soil layer, the pH explained most of the variance in microbial composition. In the deeper surface soil layers, nutrients such as carbon, nitrogen and phosphorus determined the microbial abundances and composition. Our results suggest that the soil microbial community is mainly indirectly influenced by aboveground diversity. Changes in soil pH or the soil nutrient status that are driven by specific plant traits like leave litter quality drive these indirect changes. Specific direct interactions are most reasonable for mycorrhizal fungi.     

Effects of a Microbial Inoculant and Organic Fertilizers on the Growth,Photosynthesis and Yield of Sweet Corn

Summary

A microbial inoculant known as Effective Microorganisms or EM is a mixed culture of naturally-occurring, beneficial microorganisms (predominantly lactic acid bacteria, yeast, actinomycetes, photosynthetic bacteria and certain fungi) that has been used with considerable success to improve soil quality and the growth and yield of crops, particularly in nature farming and organic farming systems. Despite this success, the exact mechanisms of how this EM elicits such beneficial effects is largely unknown. Consequently, a study was conducted to determine the effects of EM and organic fertilizer on the growth, photosynthesis, and yield of sweet corn (Zea mays L.) under glasshouse conditions, compared with chemical fertilizer. An organic fertilizer consisting of a mixture of oilseed mill sludge, rice husk and bran, and fish processing waste, was inoculated and fermented with EM as the microbial inoculant. The organic fertilizer and chemical fertilizer were then applied to respective pots to compare the growth, yield and physiological response of sweet corn plants. EM applied with the organic fertilizer was shown to promote root growth and activity, and to enhance photosynthetic efficiency and capacity, which resulted in increased grain yield. This was attributed largely to a higher level of nutrient availability facilitated by EM application over time. Interestingly, during the early stage of the experiment, the growth and dry matter yield of plants that received organic fertilizer were actually lower than those treated with chemical fertilizer that provided higher initial levels of macronutrients. However, during the intermediate and late growth stages, EM increased the nutrient availability of the organic fertilizer to a higher level, than the chemical fertilizer. Consequently, even though there was an early lower growth rate for plants that received EM-fermented organic fertilizer compared with chemical fertilizer, the final biomass and grain yield from organic fertilizer was equal to or higher than from chemical fertilizer.     

Does leaf litter quality influence population parameters of the common woodlouse, Porcellio scaber (Crustacea: Isopoda)?

Population parameters (mortality of females, reproductive success, longevity of juveniles) of the common woodlouse, Porcellio scaber (Isopoda, Oniscidea), were examined with respect to the influence of varying leaf litter attributes: pH level, microbial cellulase activity, microbial dehydrogenase activity, protein content, nitrogen content, water content, tannin content, total phenol content and toughness of the leaves. These attributes were combined by using Principal Component Analysis. We obtained three Principal Components (PC) that were defined as “acidification,”“microorganisms” and “tree species.” The PCs explained 85% of the variance of leaf litter attributes. The PC “acidification” mainly influenced the mortality of females (P<0.001), while the longevity of juveniles showed significant correlation to the PC “microorganisms” (P<0.05). The PC “tree species” showed no influence on the observed population parameters, indicating that the leaf litter species itself had no direct influence on the population parameters of P. scaber. The reproductive success of females could not be explained by either of the PCs, but was influenced by cellulolytically active microorganisms (P<0.01). From these results, we conclude that acidification and reduced microbial activity in the field will cause a decrease in population density of P. scaber. Received: 30 July 1996     

Effects of nutrient concentration on the biodegradation of crude oil and associated microbial populations in the soil

The influence of nutrient amendments on the biodegradation of a crude oil and on associated microbial populations in an agricultural soil was studied in microcosms during a 150-day experiment. Concentration and chemical composition of residual hydrocarbons (HC) were periodically monitored in series of polluted soils unfertilized and fertilized with increasing concentrations of nutrients. The decrease in HC concentration was effective in all soils over time. The maximal biodegradation extent was 62%, meanwhile the natural attenuation contributed to 47% of degradation. A permanent inhibition of hydrocarbons assimilation was recorded with a high input of nutrients. The biodegradation of saturates, aromatics and polars was respectively, permanently, temporally and not reduced by excessive fertilization in soil. Accumulation of polar metabolic by-products was demonstrated. Enumerations of total heterotrophic bacteria and hydrocarbon-adapted bacteria showed a strong stimulation in both populations. Maximum stimulation was observed with the highest input of nutrients. However, the extents of biodegradation were not concurrently improved, thus indicating that the microbial degraders were selected depending on the nutrient supply. The permanent and/or temporally inhibition of the saturated and unsaturated HC assimilation revealed that different nutrient supplies were optimum for the degradation of aliphatic and aromatic HC.     

Microbial Population and Yield of Wheat in Relation to Soil Salinity

The studies on isolations of microorganisms from four different saline soils (ECe 1.85, 5.8, 9.4 and 13.4 dS/m) and roots of wheat ( Kharchia-65 , a salt tolerant variety) plants grown in above soils reveal an interesting correlation between microbial population and soil salinity Vis-a-vis growth and yield. Though growth and yield of wheat decreased with an increase in the salinity of the soils, the fungal and bacterial populations concomitantly increased and the maximum microbial colonies were recorded from the soil, having highest salinity status. A maximum number of fungal colonies (predominantly of Aspergillus sp., Paecilomyces sp., Penicillium sp. etc.) was isolated from the root surfaces of the plants grown on soil having ECe of 1.85 dS/m, whereas a single colony of Fusarium oxysporum occurred from roots of plants of soils having an ECe of 13. 4dS/m.     

Lipid composition of Collembola and their food resources in deciduous forest stands—Implications for feeding strategies

The lipid composition of Collembola and their potential food resources was assessed in three deciduous forest stands, in order to gain insight into food web linkages under field conditions. Fatty acids (FAs) previously assigned as trophic markers in laboratory experiments were used to investigate feeding strategies in situ. As potential food sources soil microbiota and plant debris were characterised by their phospholipid fatty acid (PLFA) composition. Both the amount and the pattern of PLFAs differed between sites and soil depth, in particular the bacterial and plant marker FAs in the upper soil layer. Thus, the availability of resources for micro-detritivores varied due to forest and soil layer. The lipid composition of vital and senescent beech leaves was predominantly influenced by metabolic status and represented a quite homogenous FA resource across forest stands. Comparing Folsomia quadrioculata, Lepidocyrtus lignorum, Neanura muscorum and Pogonognathellus longicornis between the different forests revealed FA profiles to be predominantly affected by site, suggesting a diet shift depending on resources at hand. However, species-specific differences in individual FAs occurred, likely related to feeding strategy and physiological activity. Lipids of Collembola comprised low amounts of bacterial marker FAs, and bacterial consumption may occur to some extent, particularly on Gram-positives. The marker FA for predatory feeding, 20:1ω9, was found in several species, although in low amounts. This contradicts known feeding habits and caution is advisable in using 20:1ω9 as trophic marker. Overall, as indicated by high proportions of oleic (18:1ω9) or linoleic (18:2ω6,9) acid, most species were either plant litter or fungal feeders, with some transitions. The ratio 18:1ω9/18:2ω6,9 is proposed as a tool to distinguish between these two major feeding strategies in Collembola.