氮、磷对单针藻异养生长与油脂合成的影响

在异养条件下,应用Andrew方程考察了氮、磷营养盐对单针藻Monoraphidium sp.FXY-10生长的影响,并研究了氮、磷营养盐对单针藻油脂含量的影响。结果表明,磷的半饱和常数(KS,P)小于氮的半饱和常数(KS,N),说明磷对单针藻生长的影响大于氮。此外,在NaNO3质量浓度为1 g/L时,生物量产率(253.77 mg/(L·d))、油脂产率(110.36 mg/(L·d))、油脂含量(43.49%)达到最大值;在K2HPO4质量浓度为0.1 g/L时,生物量产率(323.54 mg/(L·d))、油脂产率(136.83 mg/(L·d))、油脂含量(42.29%)达到最大值。并且在氮、磷缺乏的情况下,油脂含量相对较高。     

培养条件对丝状微藻克里藻生长与亚油酸合成的影响

为开发亚油酸生产新资源,对筛选获得的一株丝状微藻克里藻,考察培养基氮浓度、培养基磷浓度、光强、培养温度和环境pH对其生长、氮消耗、油脂含量和油脂脂肪酸组成的影响。结果表明：培养基氮浓度对克里藻生长没有明显影响,但高氮不利于油脂和不饱和脂肪酸的合成;培养基磷浓度过低会抑制细胞生长,过高对细胞有毒害作用;适当提高光强有利于细胞生长,但对细胞内油脂含量影响不大,低光强培养有利于亚油酸等不饱和脂肪酸的合成;培养温度对克里藻生长与油脂积累影响不大,低温培养有利于亚油酸的合成;环境pH对细胞生长、油脂积累和亚油酸合成影响明显,pH 6.0～7.5的弱酸-中性条件下细胞生长最快,油脂含量更高;控制初始氮浓度3～6 mmol/L、磷浓度0.115～0.230 mmol/L、光强100～300μmol/(m²·s)、培养温度15～30℃、环境pH 7.5左右,克里藻细胞可积累42%左右的油脂,油脂中亚油酸含量在65%～75%。综上,丝状微藻克里藻是一种有潜力的亚油酸生产新资源。     

硝态氮对Nannochloropsis oculata生长及合成胞内组分的影响

研究了硝态氮对Nannochloropsis oculata C170细胞生长及胞内组分合成的影响。以硝酸钠为氮源考察不同氮浓度下藻细胞生长、氮消耗及油脂含量变化,并在此基础上分析氮限制处理时油脂、总糖及蛋白等胞内组分合成差异。结果表明:N.oculata C170在42.5mg/L氮浓度时生长最佳,其生物量、比生长速率及产率最高,分别为0.59g/L、0.275d-1和50.98mg/(L·d)。油脂含量与氮浓度呈明显负相关,氮浓度为12.5mg/L时,油脂含量和产率最高,分别为29.17%和11.40mg/(L·d)。而胞内多不饱和脂肪酸比例随着氮浓度的升高显著增加,其中EPA含量由8.06%升高到18.76%。此外藻细胞在限氮培养时,其油脂含量增加至23.07%,为最初含量的2.8倍,同时总糖含量升高了76%左右,叶绿素a和蛋白含量则分别下降了大约29%和24%。高浓度硝态氮有利于N.oculata C170细胞生长及胞内EPA积累,低浓度硝态氮诱导藻细胞油脂积累并与糖类合成、色素和蛋白降解相关联。     

培养条件对湛江等鞭金藻生长和油脂产率的影响

为提高微藻油脂产率和优化培养条件,以湛江等鞭金藻(Isochrysis zhanjiangensis)为研究对象,探讨了营养方式、光强和NaNO_3浓度对微藻生长和产物积累的影响以及培养过程中氮消耗与微藻生长间的关系。结果表明,湛江等鞭金藻生长越快,对氮的吸收越多,兼养较光自养和光异养消耗更多的氮以满足生长需要。充足的氮源和兼养培养条件下,蛋白质积累较多;氮浓度和光强较低条件下,油脂积累较多。光强为100μmol/(m2·s)、NaNO_3质量浓度为75 mg/L、光异养条件下油脂含量最高为46%,生物量质量浓度为0. 46 g/L;光强为100μmol/(m2·s)、NaNO_3质量浓度为750 mg/L、兼养培养时生物量质量浓度最高为2. 20 g/L,油脂含量为32. 77%。综合考虑油脂产率和节约成本等因素,湛江等鞭金藻最高油脂产率80. 06 mg/(L·d),在光强为100μmol/(m2·s)、NaNO_3质量浓度为375 mg/L、兼养培养条件下获得,此时多不饱和脂肪酸占总脂肪酸含量也较高(30. 82%),因此是生产微藻油脂的合适条件。     

淡水绿藻在培养基中生长及油脂积累研究

为筛选出最适合进行油脂生产的藻株及其较适生长和油脂积累的培养基,采用柱状光生物反应器进行一次性培养,对微藻Tetranephrisbrasiliensis DL12、Ankistrodesmusgracilis CJ09、Ankistrodesmus sp.CJ02及Desmodesmussubspicatus WC01在4种常用淡水绿藻培养基BG11、3N-BBM、SE及TAP中的生长和油脂积累进行研究。结果表明:3N-BBM有利于微藻的生长和生物量的积累,BG11有利于微藻细胞内油脂的积累;16组培养试验中,Tetranephrisbrasiliensis DL12在3N-BBM中的生物量产率((257.65±45.52)mg/(L·d))和油脂产率((80.34±14.19)mg/(L·d))最高,Ankistrodesmusgracilis CJ09在BG11中的油脂含量(42.72%±0.60%)最高。Tetranephrisbrasiliensis DL12最具油脂生产潜力,其最适生长和油脂积累的培养基为3N-BBM。     

Paenibacillus polymyxaZJ-9混合发酵菊粉和葡萄糖合成R,R-2,3-丁二醇

在7.5 L发酵罐上考察了Paenibacillus polymyxa ZJ-9混合发酵菊粉和葡萄糖合成R,R-2,3-丁二醇的工艺条件。选用菊芋菊粉粗提液为发酵前期底物,分析比较不同初始菊粉浓度下的细胞比生长速率(μ)和产物比合成速率(qp),进而研究了补糖种类和不同补料方式对合成R,R-2,3-丁二醇的影响。结果表明,初始菊粉75.0g/L,当发酵到24 h、31 h时,分别添加15.0 g/L的葡萄糖,发酵效果最佳,44 h时,产物产量达到最高值47.8 g/L,与分批发酵相比,糖转化率由原来的34.9%提高到45.5%,生产强度由原来的0.70 g/(L·h)提高到1.09 g/(L·h),并且副产物乙偶姻、残糖浓度相对较低。     

混合碳源对地衣芽孢杆菌发酵合成杆菌肽的影响

在10 L发酵罐水平研究了地衣芽孢杆菌批发酵、补料(葡萄糖、乳糖)批发酵对细胞生长以及溢流代谢和杆菌肽合成的影响。批发酵过程中,细胞28 h达到峰值(91×10~8CFU/mL)后自溶,杆菌肽效价32 h达到峰值(960 U/mL)后逐渐降解。20~28 h流加葡萄糖批发酵的峰值生物量(24 h)为115×10~8CFU/mL,比对照提高了26%。但是,流加葡萄糖后杆菌肽合成速率(20~40 h)是17.2 U/(mL·h),仅为补料前(20 h之前)的53%。基料添加乳糖批培养的峰值生物量(32 h)为110×10~8CFU/mL,比分批发酵提高了20.6%,并与流加葡萄糖批发酵接近。同时,杆菌肽以29 U/(mL·h)的速率持续合成至40 h的1 143 U/mL,比分批发酵效价提高了19%。     

生物柴油副产品粗甘油浓度对裂殖壶菌生长与积累油脂的影响

在研究了生物柴油副产品粗甘油培养裂殖壶菌(Schizochytrium sp.)WZU6961产油脂的优化培养条件的基础上,对粗甘油浓度对裂殖壶菌生长和积累油脂的影响进行研究。结果表明,在温度、溶氧及培养基其他成分相同的培养条件下,随着粗甘油浓度的增加,菌体油脂含量和脂肪酸组成没有显著的变化;但甘油的生物量和油脂得率系数以及生物量生产率和油脂生产率逐渐下降,说明粗甘油浓度过高对细胞的生长有抑制效应;当粗甘油质量浓度分别为30 g/L和60 g/L时,生物量生产率分别为0.94 g/(L·h)和0.87 g/(L·h),油脂生产率分别为0.69 g/(L·h)和0.64 g/(L·h),两者的生物量生产率和油脂生产率比较接近,因而可以得出适宜的粗甘油质量浓度为30 g/L。在粗甘油质量浓度30 g/L下,发酵时间26 h,生物量、菌体油脂含量和DHA占油脂的比例分别为(24.38±1.42)g/L、(74.08±2.20)%和23.72%。     

氮、磷浓度对小球藻生长及油脂积累的影响

含油微藻是非常有前景的生产生物柴油的材料,其生物量和油脂含量是决定其经济可行性的重要指标。培养基组成对含油微藻的生长与油脂积累具有重要影响。实验以采自青岛海域的一株海水小球藻为研究对象,在摇瓶中考察培养基氮源、磷源浓度对小球藻生长及其油脂积累的影响。结果表明:在一定范围内,增加氮源浓度能提高小球藻生长速率,但磷源对小球藻生长影响不明显;随着氮、磷源浓度的降低,小球藻总脂和中性脂含量均逐渐增大,氮源起的作用更加显著,在0.220mmol/L的低氮胁迫下获得了最高的细胞总脂含量,总脂占细胞干重的33.5%±0.3%。氮源浓度为0.441mmol/L时,小球藻的油脂产率最高,为(10.58±0.29)mg·L-1·d-1。培养基中低磷浓度有利于小球藻的油脂积累,但差别不明显。     

产油微藻的筛选及油脂含量测定

为了促进微藻领域研究和微藻生物燃料的生产,从潍坊地区多种生境中分离、筛选产油微藻,并对产油微藻生长情况和油脂积累情况进行研究。结果表明:共分离出49株微藻,其中产油微藻19株;产油微藻的生物量为1.39~6.36 g/L,油脂含量为11.16%~45.62%;6株油脂产率大于90mg/(L·d)微藻在培养的12~15 d产油能力最高,6株微藻最佳收获时间在培养后的14 d。     

岭南黄鸡炖鸡汤过程中营养及风味物质的变化

以不同饲养期（90 d、120 d、150 d）的岭南黄鸡为原料,探究不同炖制时间（1 h、2 h、3 h）炖鸡汤的营养成分、理化性质、游离氨基酸及挥发性风味物质的变化。结果表明,随着炖制时间的延长,鸡汤中的脂肪含量、蛋白质含量、b*值、可溶性固形物、总游离氨基酸含量均逐渐上升,汤产出率则相反,随着时间的增加而减少。120 d岭南黄鸡炖鸡汤的蛋白质含量较高,炖制3 h后达到6.17%。120 d炖2 h鸡汤的L*值最大为50.91,鸡汤色泽较为清亮。各鸡汤中谷氨酸和丙氨酸的含量最高,分别在380.59~2467.01 mg/kg、240.34~1309.55 mg/kg之间。120 d炖2 h、120 d炖3 h鸡汤的谷氨酸（1857.08 mg/kg、2467.01 mg/kg）和丙氨酸（1042.50 mg/kg、1309.55 mg/kg）含量高于其它7组鸡汤,其滋味更为鲜美。各鸡汤的挥发性风味物质共鉴定出有85种,醛类物质的相对含量最高,在63.99%~85.44%之间。各鸡汤共同含有的14种风味物质中,己醛的相对含量最高在50%左右。90 d炖2 h鸡汤的挥发性风味成分种类最多为45种,其次是120 d炖2 h鸡汤为42种。该研究揭示了岭南黄鸡饲养期与炖汤时间对其鸡汤品质的影响规律,表明了炖制时间适宜（2 h）,饲养期适当（120 d）的岭南黄鸡鸡汤的综合品质最佳。     

高产油脂隐球酵母菌发酵条件研究

通过摇瓶培养,对各项与菌体产油脂相关因素进行单因素及正交试验,确定摇瓶发酵培养最佳产油脂条件:碳源,葡萄糖120g/L;氮源,硝酸钾1g/L,玉米浆2.5g/L;C/N:400,硫酸镁1.5g/L,硫酸锰2mg/L;培养温度为28℃,接种量10%,发酵时间96h,起始pH7.0,最后可得油脂产量14.32g/L,菌体生物量25.67g/L,油脂含量55.8%。     

Reduction of Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis in chicken manure by larvae of the black soldier fly

Green fluorescent protein-labeled Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis were inoculated at 10(7) CFU/g into cow, hog, or chicken manure. Ten- or 11-day-old soldier fly larvae (Hermetia illucens L.) (7 to 10 g) were added to the manure and held at 23, 27, or 32 degrees C for 3 to 6 days. Soldier fly larvae accelerated inactivation of E. coli O157:H7 in chicken manure but had no effect in cow manure and enhanced survival in hog manure. The initial pH values of the hog and chicken manure were 6.0 to 6.2 and 7.4 to 8.2, respectively, and it is surmised that these conditions affected the stability of the larval antimicrobial system. Reductions of E. coli O157:H7 populations in chicken manure by larvae were affected by storage temperature, with greater reductions in samples held for 3 days at 27 or 32 degrees C than at 23 degrees C. Pathogen inactivation in chicken manure by larvae was not affected by the indigenous microflora of chicken manure, because Salmonella Enteritidis populations in larvae-treated samples were approximately 2.5 log lower than control samples without larvae when either autoclaved or nonautoclaved chicken manure was used as the contaminated medium during 3 days of storage. Extending the storage time to 6 days, larvae again accelerated the reduction in Salmonella Enteritidis populations in chicken manure during the first 4 days of storage; however, larvae became contaminated with the pathogen. After 2 days of feeding on contaminated manure, Salmonella Enteritidis populations in larvae averaged 3.3 log CFU/g. Populations decreased to 1.9 log CFU/g after 6 days of exposure to contaminated chicken manure; however, the absence of feeding activity by the maggots in later stages of storage may be responsible for the continued presence of Salmonella Enteritidis in larvae. Transfer of contaminated larvae to fresh chicken manure restored feeding activity but led to cross-contamination of the fresh manure.     

Effects of feeding in free-range conditions or in confinement with different dietary MUFA/PUFA ratios and α-tocopheryl acetate, on antioxidants accumulation and oxidative stability in Iberian pigs

The experiment was undertaken to provide information of the influence of feeding either free-range or in confinement with different dietary MUFA/PUFA ratios and α-tocopheryl acetate supplementation (40 vs. 200 mg/kg) on tocopherol content and susceptibility to lipid oxidation of muscle and microsomes in Iberian pigs. The grass provided to the pigs had a similar α-tocopherol concentration to that observed for diets supplemented with 200 mg/kg α-tocopheryl acetate, and acorns supplied fourfold higher content of γ-tocopherol than the experimental diets. The α- and γ-tocopherol contents of muscle reflected the tocopherol concentration of the diets. Mono and Medium diets produced a similar MUFA/PUFA ratio in neutral and polar lipids of pig muscle to those fed outdoors. The lowest TBARS numbers were found in muscle samples from pigs fed a MUFA-enriched diet in confinement. No significant influence of free-range feeding or dietary fat on drip loss was found. However, α-tocopheryl acetate supplementation reduced (P<0.05) drip loss. Dietary vitamin E supplementation decreased the membrane lipid oxidation by 18% after 120 min. However, free-range feeding decreased the extent of microsome oxidation by 20%, 56% and 82% after 120 min when compared with those groups fed in confinement with high, medium and low MUFA/PUFA ratios, respectively. The hexanal concentration of muscle showed a similar trend to that observed for microsome induced-oxidation, suggesting, that hexanal determination is a more accurate method to measure lipid oxidation in iberian pig muscle than the thiobarbituric acid test.     

耐氨米根霉的分批补料发酵及发酵动力学初探

以氨水为中和剂,替代CaCO3,对耐氨米根霉R.oryzaeJS-N0-2-02进行15L自动发酵罐的分批和分批补料发酵及其发酵动力学的初步研究,结果表明,降低起始糖浓度,产酸期补糖可明显提高菌体L-乳酸比生产速率和耗糖产酸能力,提高L-乳酸产量和纯度,降低残糖。在发酵起始时添加1 g/L CaCO3能进一步提高补糖发酵的L-乳酸比生产速率,增强发酵后期菌体耗糖产酸能力,从而进一步提高L-乳酸产量和纯度,降低残糖。发酵结果:起始糖浓度为120 g/L,25h时补糖使最终发酵总糖浓度达137 g/L,发酵培养60 h,L-乳酸产量可达101.8 g/L,纯度97.3%,菌体耗糖转化率76%,比生产速率0.27 g/g.h,残糖降至3 g/L。     

Effects of combinations of lactoperoxidase system and nisin on the behaviour of Listeria monocytogenes ATCC 15313 in skim milk

Individual or combined effects of nisin (100 or 200 IU/ml) and the lactoperoxidase system (LPS) were analysed against 1 x 10(4) cfu/ml Listeria monocytogenes ATCC 15313 cells in skim milk, at 25 degrees C for 15 days. Nisin induced an immediate bactericidal effect and LPS a 48 h bacteriostatic phase which in both cases was followed by re-growth of L. monocytogenes. LPS and nisin added together at t0 showed a synergistic and lasting bactericidal effect which after 8 days and until 15 days resulted in no detectable cells in 1 ml of milk. When LPS was added to cells already in contact with 100 or 200 IU/ml nisin for a period of 4 h, the inhibitory activity was enhanced with no L. monocytogenes detectable after 72 or 48 h, respectively, and until 15 days. When LPS was added after 12 h, the nisin bactericidal phase was followed by re-growth. When nisin, 100 or 200 UI/ml, was added to cells already in contact with LPS over 24 h, L. monocytogenes was not detectable after 196 and 244 h, respectively, without any re-growth. For nisin addition after 72 h, cell counts were 8 log10 cycles lower than in the control milk after 196 h, but population levels were similar to the control within 15 days. The best combination to inhibit L. monocytogenes ATCC 15313 was nisin present at t0 followed by the LPS addition 4 h later, when the maximum inhibitory effect of nisin was reached.     

Streptococcus zooepidemicus H23生产透明质酸营养条件的优化

在发酵罐水平上研究了酵母粉用量、初糖浓度和碳氮比以及补加葡萄糖对Strepto coccuszoopeidemicusH2 3发酵生产透明质酸的影响。利用上述条件在 5L罐上进行发酵实验 ,16h时发酵液中透明质酸质量浓度为 4 83g/L。     

Feeding of palm oil fatty acids or rapeseed oil throughout lactation: Effects on energy status,body composition,and milk production in Norwegian dairy goats

The objective of this experiment was to examine how supplements of rapeseed oil or palm oil fatty acids would affect milk production and composition, body lipid stores, and energy balance in 30 multiparous goats of Norwegian dairy goat breed. The experiment lasted 230 d, with 1 to 120 d in milk (DIM) for indoor feeding (P1), 120 to 200 DIM for mountain grazing (P2), and 200 to 230 DIM for indoor feeding (P3). Grass silage was fed according to appetite during indoor feeding periods. After an adjustment period (1–60 DIM) when the control diet was given to the goats, the animals were subdivided into 3 groups of 10 goats. Treatments (60–230 DIM) were (1) basal concentrate (control; no added fat); (2) control concentrate with 8% (added on air-dry basis) hydrogenated palm oil enriched with palmitic acid (POFA); and (3) control concentrate with 8% (added on air-dry basis) rapeseed oil (RSO). Individual energy balances based on energy intake and milk production were estimated on 10, 30, 60, 90, 120, 200, and 230 DIM. At the same times, body weight (BW), body condition score (BCS), body mass index, and body tissue stores using computed tomography were monitored. Silage intake was depressed by POFA throughout the experimental period. Reduced BW and body mass index were observed in the POFA and RSO groups, whereas no effect on BCS or body composition was observed throughout lactation. Generally, a minor decrease in BW was observed from 10 to 120 DIM (only 0.6 kg on average) and the total amount of body lipid was reduced by 4.4 kg. During the mountain grazing period, a further reduction in body lipid stores (2.7 kg) was observed, and BW was reduced by 3.9 kg in the same period. The goats mobilized, on average, 72% of their fat reserves during the first 200 DIM. In this period, dietary fat supplementation did not reduce the mobilization of adipose tissue but resulted in greater milk fat yield (2 kg more, on average, compared with the control group). Milk yield was not affected by POFA or RSO supplementation. Milk fat content was higher in the POFA group than in the control and RSO groups. Milk protein and lactose contents were not affected by lipid supplements. In late lactation, a rapid accumulation of fat deposits followed the intense mobilization during the grazing period. Dietary lipid supplements had no effect on milk fat yield at this stage. Milk production depends heavily on the ability to mobilize body lipid stores, and neither POFA nor RSO supplements at rates used in our study affected this mobilization.     

黄嘌呤和谷氨酰胺对枯草芽孢杆菌XGL产腺苷的影响

该研究以枯草芽孢杆菌（Bacillus subtilis）XGL为出发菌株,探究黄嘌呤和谷氨酰胺添加量及添加方式对其产腺苷的影响。结果表明,底物中添加100 mg/L黄嘌呤并在发酵16 h后持续向发酵液中流加3 g/L的黄嘌呤溶液200 mL可使腺苷产量达到34.4 g/L,相比于不流加黄嘌呤时腺苷产量（11.2 g/L）提高207%。在此基础上,再向底物中添加6 g/L谷氨酰胺,发酵32 h之后持续向发酵液中流加6 g/L的谷氨酰胺,腺苷产量达到45.8 g/L,相比于不添加谷氨酰胺腺苷产量（34.4 g/L）提高33%。因此,在B. subtilis XGL发酵过程中,可以通过底物添加和流加补料的发酵方式加入一定量的黄嘌呤和谷氨酰胺以提高腺苷产量。     

阿卡波糖发酵过程的放大研究

研究了阿卡波糖产生菌游动放线菌A-56在30 m3罐上的发酵放大策略。首先通过摇瓶分批补料发酵,考察了补料培养基中麦芽糖和葡萄糖配比对阿卡波糖合成的影响,结果表明,麦芽糖和葡萄糖的配比对阿卡波糖的生物合成具有显著的影响,且麦芽糖和葡萄糖的配比为3∶1最利于阿卡波糖合成;在此基础上,在100 L发酵罐上进一步考察了碳源控制对阿卡波糖发酵的影响,结果表明,补料阶段的发酵液总糖和还原糖浓度分别控制在75～80 g/L和45～50 g/L时,最利于阿卡波糖合成。因此,筛选出总糖和还原糖(麦芽糖和葡萄糖)这两个关键参数作为放大因子,成功地实现了阿卡波糖从100 L罐到30 m3罐的工业化发酵放大,最终(168 h)的阿卡波糖产量达到4 327 mg/L。