Characteristics of L-lactic Acid Production byRhizopus oryzae mutant RL6041

A high-yield mutant strain Rhizopus oryzae RL6041 induced by ions implantation was used in the present study. L (+)-lactic acid was generated by RL6041 grown on liquefied corn starch as a substrate. With optimal conditions (Liquefied corn starch 150g/L, (NH₄)₂SO₄ 2.0g/L, MgSO₄·7H₂O 1.0g/L, ZnSO₄·7H₂O 2g/L, KH₂PO₄ 0.2g/L, CaCO₃ 8%, medium size 20/250Ml, seed age 6h, fermentation temperature 38° C), the yield of L (+)-lactic acid in shake-flask reached 133∼136g/L after 36h, indicating that the conversion rate was as high as 88%∼91%, and the productivity was 3.75g/L·h. There was almost a 70% increase in lactic acid production compared with the original strain RE3303.     

Solid-state fermentation of Lathyrus sativus seeds using Aspergillus oryzae and Rhizopus oligosporus sp T-3 to eliminate the neurotoxin β-ODAP without loss of nutritional value

The presence of a neurotoxic amino acid, 3-N-oxalyl-L-2,3-diaminopropanoic acid (β-ODAP), in the seeds of grass pea (Lathyrus sativus) is the cause of an irreversible spastic paraparesis, neurolathyrism, after over-consumption. This is a negative factor in an otherwise very tasty, nutritious, easily cultivated and hardy food crop in Asia and Africa. The reduction of β-ODAP to less than 10% of the original content has been reached by fermenting L sativas Jamalpur seeds with Aspergillus oryzae NRRL 1988 for 48 h, followed by fermentation with Rhizopus oligosporus sp T-3 for 48 h. Other nutritional qualities were also improved in the fermented seed meal: increased content of protein, higher amino acid scores for sulphur-containing and aromatic amino acids, better resistance to high temperature and to oxidation, and drastic reduction of the flatulence factors.     

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.     

储粮环境中米象发生与CO2含量变化的关系研究

为阐明储粮环境中害虫发生与CO_2气体含量变化的关系,研究不同含水量的小麦感染不同虫口密度(0、2、5、10、20、30头/kg)米象后储藏环境中CO_2气体体积分数变化的情况。结果表明:对于含水量相同的储藏小麦,储藏环境中CO_2气体体积分数随虫口密度的增加和储藏时间的延长而显著增加。对于含水量12%的小麦,初始感染虫口密度为30头/kg的储粮环境中CO_2气体体积分数最初为0.413%,在第30天达到最大值为14.777%。对于含水量14%的小麦,初始感染虫口密度为30头/kg的储粮环境中CO_2气体体积分数最初为0.720%,在第15天达到最大值为17.197%。本研究结果为今后通过检测CO_2体积分数变化来监测粮堆中虫害发生情况提供了可靠信息。     

米曲霉菌种选育中原生质体制备方法的研究

米曲霉(Aspergillus oryzae)是一种好气性真菌,在生长过程中可以产生多种酶,广泛的应用于食品发酵工业中。因此,米曲霉优良菌株的选育有着重要意义和实用价值。围绕原生质体制备的方法,重点阐述了菌丝和孢子制备原生质体的优缺点以及破壁酶的选择,为米曲霉菌种选育提供理论支持和技术帮助。     

米根霉原生质体电融合条件研究

以米根霉突变株mut-A、mut-B为亲本,采用双亲灭活标记筛选融合子,对亲本灭活条件、原生质体电融合条件进行了研究。实验结果表明,0.6mol/L山梨醇溶液为最适的渗透压缓冲液,mut-A、mut-B的灭活条件分别为50℃加热6min及紫外照射180s。原生质体在电场中排队所需的细胞浓度为1×107/mL,交变电场电压为8V;最佳的电融合参数为直流脉冲电压260V,脉冲持续时间40μs,脉冲次数2次;最高融合率可达7.29±0.71%。     

米曲霉氨基酰化酶拆分DL茶氨酸

DL-茶氨酸经乙酰化可生成N-乙酰-DL-茶氨酸，然后利用米曲霉氨基酰化酶拆分N-乙酰-DL-茶氨酸可以获得L-茶氨酸。本文对氨基酰化酶酶促反应也进行了初步研究，考察了反应温度、反应时间、pH值和底物浓度等因素对酶促反应的影响。实验表明，转化温度40℃、转化时间30h、pH为7．0和底物浓度0．2mol／L时，目的产物L-茶氨酸的产率最高。     

Extractive fermentation for fumaric acid production by Rhizopus oryzae

Low product concentration and high cost of recovery process have motivated the study of in situ removal of fumaric acid from fermentation broth. After a series of screenings, an integrated process with fumaric acid fermentation and extraction was developed. Under this integrated process, fumaric acid production and productivity increased from 18.06 g/L to 34.23 g/L, and from 0.27 g/L/h to 0.57 g/L/h, respectively. Neutralizing agent utilization decreased by 58.75%, and 140.7 g/L ammonium fumarate was obtained after back extraction, which could be directed used to produce related derivatives without concentration. Thus, the integrated process was more economic and environmental friendly.     

酱油曲菌酶系及其产酶能力

研究了Ａｓｐｅｒｇｉｌｌｕｓ ｏｒｙｚａｅ Ａｓ．３９５１,ＪＰ－ＤＱ－１和ＪＰ－Ｗ的酶系和在不同培养基上的产酶能力。结果表明：上述三种菌在小麦曲、麦麸曲、米曲、浓酱油曲和白酱油曲上均可产生α－淀粉酶、糖化酶、纤维素外切酶、果胶酶和蛋白酶。ＪＰ－Ｗ在小麦曲、麦麸曲和白酱油曲上产酶能力最佳;ＪＰ－ＤＱ－１在浓酱油曲上产酶能力较强;Ａｓ．３９５１在米贡上产酶能力强。建议用ＪＰ－ＤＱ－１生产浓酱油,用Ｐ