控制发酵过程氧化还原电位优化酿酒酵母乙醇生产

利用氧化还原电极,研究了在厌氧条件下将氧化还原电位值(ORP)控制在不同水平(-50mV、-100mV、-150mV、-230mV)对乙醇发酵过程的影响。试验结果表明,不同的ORP值水平对乙醇得率,甘油形成、有机酸分泌、生物量和菌体死亡率的影响有明显的差异。当ORP为-50mV时的生物量是ORP为-100mV时的1.26倍、ORP为-150mV时的1.86倍、ORP为-230mV时的2.59倍,甘油浓度分别是后三者的1.2倍、1.1倍、1.7倍,而乙醇浓度却分别只有后三者的0.87倍、0.49倍、0.51倍。综合考虑生物量、乙醇浓度、甘油产量、残糖的测定结果,表明将ORP控制在-150mV时对乙醇发酵极为有利。说明可以用ORP电极来精确控制厌氧发酵条件,从而为酵母细胞合理分配代谢流以实现乙醇生产最优化的宏观控制提供了一种有效的手段。     

棉花根际解磷菌的解磷能力和分泌有机酸的初步测定

利用特殊培养基对盐碱地棉花根际解磷菌进行了分离以及pH值和分泌有机酸能力的初步测定。利用溶磷圈法筛选出10个解磷能力较高的菌株进行深入研究,其中液体培养条件下测定了菌株的溶磷能力,有效磷在4.04~185.63 mg/L,其中wpL2溶磷量达到185.63 mg/L;测定了培养液pH值,下降到5.12~6.67,但是pH与溶磷量之间没有线性关系,测定了培养液的有机酸含量,菌株溶磷量与有机酸总量没有线性相关性,其中所分离到的解无机磷菌株均可以分泌酒石酸,除此之外,wpc1还分泌乙酸,wpc2和wpL2还分泌柠檬酸;分离到的解有机磷菌株均可分泌乙酸,除此之外,ypL1和ypc2分泌酒石酸,ypL3分泌柠檬酸,ypL2和ypc3分泌柠檬酸和丁二酸,均不能产生苹果酸。     

四川岷山小麂的种群性比、社会结构和活动节律

小麂(Muntiacus reevesi)主要分布在东亚长江以南的地区,是我国分布范围最广的麂属物种.本研究基于四川省岷山山脉6个自然保护区2011-2020年的红外相机调查数据,共布设有效调查位点726个,完成75320个相机日的有效调查工作量;在其中133个相机位点上拍摄到小麂照片和视频20236份,独立探测190...     

Effect of silicate on phosphate availability for rice in a P-deficient soil

In a pot experiment the effect of silicate on P availability for rice grown in a P-deficient soil with and without flooding was analyzed. Treatments were designed as follows: C (control: Yakuno soil), SS (sodium silicate application, at 0.47 mg Si g^-1 soil) and SC (sodium carbonate application). In order to separate pH effect from Si effect, SC was adjusted to the same pH as SS.Soil pH of SS and SC increased by 1.0 unit. Shoot dry weight of SC plants, and more so of SS plants, increased under both nonflooded and flooded conditions. P concentrations in the shoots were not increased under either condition of SS and SC. With SS, Si concentration in the shoots significantly increased, Mn concentration significantly decreased, resulting in a higher P/Mn ratio in the shoot, but not with SC. Both SS and SC increased N concentration in the shoots nearly two times compared with control under both conditions.Adsorption experiments showed that neither SS nor SC decreased P adsorption by soil. SS also could not displace the adsorbed P in soil samples which had previously either received P or not.These results suggest that the beneficial effects of silicate on rice growth do not result from increasing P availability in soil. The Si effect may be attributed to decreasing Mn uptake, thus indirectly improving P utilization in the plant.     

肠通透性改变的研究初报

本文用气相色谱测定烧伤猪和羊的ＭＳＯＦ动物模型尿内乳果糖和甘露醇分泌比率（Ｌ／Ｍ）。烧伤猪治疗组７２小时Ｌ／Ｍ分泌比率为０．０２４±０．００７,而对照组为０．０２６±０．００３,伤前Ｌ／Ｍ分泌比率为０．００７±０．００５,与伤前比较,无显著性差异。这说明Ｌ／Ｍ分泌比率升高与烧伤前期治疗及伤后天数无关。而在羊的ＭＳＯＦ的动物模型内Ｍ组中,输入内毒素４小时及伤后３天的Ｌ／Ｍ分泌比率为０．６２±０．２、１．７０±０．６０,对照组为０．２８±０．２５、０．２０±０．１０,伤前为０．０２９±０．０２,Ｌ／Ｍ分泌比率升高显著（Ｐ＜０．０５）,提示内毒素血症可能与肠通透性改变之间具有密切联系。     

On the trophic fate of Phaeocystis pouchetii (Hariot). II. Grazing rates of Calanus hyperboreus (Krøyer) on diatoms and different size categories of Phaeocystis pouchetii

Experiments were conducted with CIV and C V copepodites of Calanus hyperboreus (Krøyer) to determine if they would feed on the prymnesiophyte Phaeocystis pouchetii (Hariot). We used analysis of gut pigment to estimate ingestion and clearance rates. In applying this methodology we have demonstrated that pigments can be completely extracted from whole animals within 90 min, and that laborious procedures of tissue homogenization and centrifugation are not required. We conducted two experiments. In the first experiment Stage IV copepodites were exposed to ≈1 mg C·1⁻¹ of either P. pouchetii flagellates, small colonies (25–200 μm), large colonies (> 200 μm) or mixed diatoms > 25 μm (primarily Chaetoceros socialis Lauder and Nitzschia grunowii Hasle). Ingestion rates and daily rations were almost four times greater on both sizes of colonies than on either Phaeocystis pouchetii flagellates or mixed diatoms. Daily rations of copepodites feeding on colonies ranged from 8.1 to 12.4% · day⁻¹, well within the range previously reported for Calanus hyperboreus or sympatric copepods of similar size. From the second experiment we determined that Stage V copepodites obtained a daily ration of 6.2 to 10.8% · day⁻¹ when feeding on small colonies of Phaeocystis pouchetii. We conclude that a diet of P. pouchetii colonies should sustain the metabolic and growth requirements of Calanus hyperboreus copepodites.     

Gastric evacuation of single and multiple meals by piscivorous coho salmon,Oncorhynchus kisutch

Synopsis Gastric evacuation of multiple meals of recently emerged sockeye salmon, Oncorhynchus nerka, consumed by juvenile coho salmon, O. kisutch, were compared with that expected from a single meal evacuation rate model developed for the estimation of food consumption by coho in the field. Significant interaction occurred between meals consumed two hours apart (p<0.001). Evacuation of the first of two meals (29.9% of initial weight remaining) was significantly faster (p<0.05) than that of a single meal (36.1% of initial weight remaining) after four hours, whereas evacuation of the second meal (72.2% of initial weight remaining) was significantly slower (p<0.001) than that of single meals (50.6% of initial weight remaining) after two hours. The total weight of the multiple meal remaining after four (0.191 g), six (0.138 g) and eight (0.070 g) hours averaged within 6% of that predicted by the single meal evacuation model (0.186 g, 0.115 g and 0.073 g, respectively). These data suggest that the stomach evacuation model based on single meals is adequate for estimating the evacuation of prey consumed by continuously feeding coho salmon.     

An examination of two concentrate allocation strategies which are based on the early lactation milk yield of autumn calving Holstein Friesian cows

The objective of this experiment was to compare the effects of two concentrate feeding strategies offered with a grass silage and maize silage diet on the dry matter (DM) intake, milk production (MP) and estimated energy balance of autumn calved dairy cows. Over a 2-year period, 180 autumn calving Holstein Friesian cows were examined. Within year, cows were blocked into three MP sub-groups (n=9) (high (HMP), medium (MMP) and low (LMP)) based on the average MP data from weeks 3 and 4 of lactation. Within a block cows were randomly assigned to one of two treatments (n=54), flat rate (FR) concentrate feeding or feed to yield (FY) based on MP sub-group. Cows on the FR treatment were offered a fixed rate of concentrate (5.5 kg DM/cow per day) irrespective of MP sub-group. In the FY treatment HMP, MMP and LMP cows were allocated 7.3, 5.5 and 3.7 kg DM of concentrate, respectively. The mean concentrate offered to the FR and FY treatments was the same. On the FR treatment there was no significant difference in total dry matter intake (TDMI, 17.3 kg) between MP sub-groups. In the FY treatment, however, the TDMI of HMP-FY was 2.2 kg greater than MMP-FY, and 4.5 kg greater than LMP-FY (15.2 kg DM). The milk yield of LMP-FR was 3.5 kg less than the mean of the HMP-FR and MMP-FR treatments (24.5 kg). The milk yield of the HMP-FY treatment was 3.6 and 7.9 kg greater than the MMP-FY and LMP-FY treatments, respectively. The difference in MP between the HMP sub-groups was 2.6 kg, which translates to a response of 1.4 kg of milk per additional 1 kg of concentrate offered. There was no significant difference in MP between the two LMP sub-groups; however, MP increased 0.8 kg per additional 1 kg of concentrate offered between cows on the LMP-FR and LMP-FY treatments. The estimated energy balance was positive for cows on the LMP-FR treatment, but negative for cows on the other treatments. The experiment highlights the variation within a herd in MP response to concentrate, as cows with a lower MP potential are less responsive to additional energy input than cows with a greater MP potential. Cows with a greater MP capacity did not substitute additional concentrate for the basal forage, which indicates an additional demand for energy based on ability of individual cows to produce milk.     

Short Communication

Abalone farmed in Australia are predominantly fed formulated feeds, while in the wild, their diet consists of a mix of macroalgae. Here we investigated the feeding behaviour of juvenile greenlip abalone, Haliotis laevigata; fed live macroalgae and formulated diets at different rations; and observed their feeding behaviour using a novel ventral video monitoring technique. Four different diets (commercial chip, experimental flake, Ulva sp. and Gracilaria cliftonii) at two feeding rations (excess vs. restricted) were tested. Diet type had no effect on abalone movement, but macroalgal diets resulted in higher feed intakes. Restricting feed rations induced greater movement. Abalone moved little during the light period and moved mostly during darkness, except for animals on the restricted feed ration where feeding commenced during the light period. On farms, this phenomenon may be a useful behavioural indicator for identifying underfed abalone. Despite their lower intake, formulated diets promoted higher energy and nutritional intake, indicating that quantity of feed consumed is not solely indicative of nutritional gain. From a research perspective, the novel ventral monitoring method has created opportunities for further behavioural studies in molluscs.