Optimization of L-lactic Acid Production of Rhizopus Oryzae Mutant RLC41-6 by Ion Beam Implantation at Low-Energy

In order to obtain an industrial strain with a higher L（＋）-lactic acid yield, the strain Rhizopus oryzae RF3608 was mutated by means of nitrogen ion beam implantation and the mutant strain RLC41-6 was isolated. Under optimal conditions the yield of L（＋）-lactic acid produced in a shake-flask reached 133 g/L - 137 g/L after 36 h cultivation, indicating that the conversion rate based on glucose was as high as 88% - 91% and the productivity was 3.75 g/L.h. It was almost a 115% increase in lactic acid production compared with the original strain RF3608.     

Studies on Mutation Breeding of High-Yielding Xylanase Strains by Low-Energy Ion Beam Implantation

As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.     

壳聚糖固定化单宁酸酶的特性研究

研究了以壳聚糖为载体交联-吸附单宁酸酶后的化学特性。结果表明：固定化单宁酸酶（简称“ITA”）的最适反应pH为3.0,原酶（简称“TA”）为5．5;ITA最适反应温度为50℃,TA为40℃;ITA的Km（app）为1．3845×10(-1)mol／L,TA为6．7500×10(-5)mol/L;ITA在pH3．0～8．0的范围内残存酶活大于60％,ITA在pH3．0～6.0范围内残存酶活大于60％;ITA在80℃的水浴中保温1h,酶活力仍未见下降,而TA在60℃水浴中保温30min酶已失活;ITA和TA在4℃和30℃的条件下,贮藏20d后,ITA的残存活性大于40％,TA的残存活性小于20％。     

花生四烯酸的研究概况及应用前景

多不饱和脂肪酸（Ｐｏｌｙｕｎｓａｔｕｒａｔｅｄ　ｆａｔｔｙ ａｃｉｄｓ,ＰＵＦＡｓ）是指含两个以上双键的一类长链脂肪酸。在微生物体内,ＰＵＦＡｓ的合成通常是以单不饱和脂肪酸、油酸为底物,合成途径中,有两个主要的反应,即碳链的增长和去饱和作用。链增长是供体（乙酰辅酶Ａ或丙二酰辅酶Ａ）上的两个碳原子被引入增加碳链长度。而亚油酸的链增长和去饱和则有两个不同的代谢方向,见图１［１］。 ＰＵＦＡｓ对人体健康的重要作用已为人们所广泛认识,有人也称它们为维生素Ｆ。天然存在的ＰＵＦＡｓ种类繁多,其中有３种显得特别…     

Study on Mutagenic Breeding of Bacillus Subtilis and Properties of Its Antifungal Substances

Bacillus subtitles JA isolated by our laboratory produced a large amount of antifungal substances, which had strong inhibitory activity against various plant pathogenic fungi,such as Rhizoctonia solani, l?usarium graminearum and so on. Ion beam implantation as a new mutagenic methods was applied in our studay. After B. subtitles JA was implanted by N^ ions,a strain designated as B. subtitles JA-026 was screened and obtained, which had a higher ability to produce those antifungal substances. A series of experiments indicated that the antifungal substances were thermostable and partially sensitive to proteinases K and tryproteinase. When the fermentating broth was fractionated with ammonium sulphate of a final saturation of 70%,the precipitate-enhanced inhibitory activity while the supernatant lost this activity. It appeared that the antifungal substances were likely to be protein.     

磁聚复配物对L-乳酸发酵液的预处理研究

对用磁聚复配物预处理L-乳酸发酵液进行了研究,讨论了pH值、复配物用量、搅拌速度与时间、温度、磁场强度对絮凝效果的影响。实验结果显示,在pH5~6,40 mg/L壳聚糖与100 mg/L Fe3O4复配,200r/min下搅拌5 min,35~55℃,外加磁场(0.5T)作用1 min的情况下,发酵液的絮凝率达到了98.5%,表明磁聚复配物对L-乳酸发酵液中的蛋白质具有优良的絮凝能力,且更大的优势在于显著提高了固液分离的速度。     

紫外线与N~+注入复合诱变选育曲酸高产菌株

为得到一株曲酸的高产菌株,从5种实验菌株中筛选得到1株米曲霉CICC-2336菌株,以其作为出发菌株,经过紫外诱变和氮离子注入诱变两种复合诱变,得到1株曲酸高产菌株,将其命名为Aspergillus oryzaeN11。该菌株经过传代6次后,性状稳定,产酸量基本不变。在接种量15%、30℃恒温、摇床180r/min条件下发酵培养7d后,其产酸量达到24.12g/L,比出发菌株提高101%。     

The Property and Application of Arachidonic Acid

Arachidonic acid(AA) is one of the most important PUFAs(polyunsaturated fatty acids) in human body.A high-yield arachidonic acid-producing strain(mortierella aplina) was selected by ion implantation(the relative content of arachidonic acid is 70.2% among all fatty acids).This paper mainly introduced the structure,distribution,source,physiologic healthcare function and application of AA.     

高产L-乳酸米根霉RE3303菌株特性研究

为了获得更适于工业生产的产乳酸菌株 ,采用低能离子诱变方法 ,对出发菌米根霉PW 35 2进行改良 ,获得高产L(+) 乳酸菌株RE330 3,发酵周期为 36h ,产酸能力达 131～ 136g/L ,最高可达 14 0g/L ,体积产酸速率达 3.6 1g/ (L·h) ,产率为 86 %～ 90 % ,产酸比PW35 2提高 75 %。     

高产二十二碳六烯酸隐甲藻的选育及其发酵条件研究

利用亚硝基胍对隐甲藻ATCC30556进行诱变处理,通过30℃高温培养初筛及摇瓶发酵复筛,得到二十二碳六烯酸(DHA)产量稳定提高的突变株LS1057,其DHA占总脂肪酸的含量从出发株的25.78%提高到32.02%。研究摇瓶发酵条件对突变株发酵的影响,结果表明：在初始pH6.5、温度26℃、转速150r/min的发酵条件下培养216h后,其生物量、总油脂产量及DHA产量分别达到14.06、3.14g/L和1.057g/L,分别比出发藻株提高了21.31%、69.73%和121.59%。