Description of Pella maoershanensis sp. n. (Coleoptera,Staphylinidae, Aleocharinae) associated with Lasius spathepus from Guangxi,South China

Pellamaoershanensis Song & Li, sp. n., collected from a colony of Lasius (Dendrolasius) spathepus in Maoershan Natural Reserve, Guangxi, is diagnosed, described and illustrated. The discovery represents the first record of the genus in South China.     

外源H2O2对盐碱混合胁迫下裸燕麦幼苗生长和抗性生理的影响

为探讨信号分子过氧化氢（H₂O₂）增强裸燕麦盐碱耐性的作用及其生理机制,以裸燕麦品种‘定莜6号’为材料,在日光温室内用珍珠岩培养幼苗至三叶一心期时叶面喷施0.01 mmol·L^-1 H₂O₂的同时根部浇灌75 mmol·L^-1盐碱混合溶液（NaCl：Na₂SO₄：NaHCO₃：Na₂CO₃=12：8：9：1）或添加H₂O₂淬灭剂二甲基硫脲（DMTU）,研究对幼苗生长及叶片光合色素含量、活性氧代谢和渗透调节物质积累的影响。结果表明：喷施H₂O₂能够缓解盐碱混合胁迫对裸燕麦幼苗生长的抑制,提高幼苗根长、株高和植株干重及叶片叶绿素a、叶绿素b、总叶绿素、类胡萝卜素含量和超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶活性,降低超氧阴离子、H₂O₂、丙二醛、抗坏血酸、谷胱甘肽和游离氨基酸含量,促进抗氧化物质类黄酮、总酚和原花青素及渗透调节物质可溶性蛋白质、可溶性糖和脯氨酸积累。添加DMTU部分或完全逆转了H₂O₂的上述作用。采用隶属函数综合评价显示,喷施H₂O₂提高了盐碱混合胁迫下裸燕麦幼苗的综合评价值D,添加DMTU完全逆转了H₂O₂对D值的提升作用。表明外源H₂O₂通过参与活性氧代谢和渗透调节物质积累等生理代谢调控缓解盐碱混合胁迫诱导的氧化伤害和生长抑制,从而提高裸燕麦对盐碱胁迫的适应能力。     

Codon Usage Decreases the Error Minimization Within the Genetic Code

The genetic code is not random but instead is organized in such a way that single nucleotide substitutions are more likely to result in changes between similar amino acids. This fidelity, or error minimization, has been proposed to be an adaptation within the genetic code. Many models have been proposed to measure this adaptation within the genetic code. However, we find that none of these consider codon usage differences between species. Furthermore, use of different indices of amino acid physicochemical characteristics leads to different estimations of this adaptation within the code. In this study, we try to establish a more accurate model to address this problem. In our model, a weighting scheme is established for mistranslation biases of the three different codon positions, transition/transversion biases, and codon usage. Different indices of amino acids physicochemical characteristics are also considered. In contrast to pervious work, our results show that the natural genetic code is not fully optimized for error minimization. The genetic code, therefore, is not the most optimized one for error minimization, but one that balances between flexibility and fidelity for different species.     

Optimization of cellulase production in batch fermentation byTrichoderma reesei

Maximum cellulase production was sought by comparing the activities of the cellulases produced by differentTrichoderma reesei strains andAspergillus niger. Trichoderma reesei Rut-C30 showed higher cellulase activity than otherTrichoderma reesei strains andAspergillus niger that was isolated from soil. By optimizing the cultivation condition during shake flask culture, higher cellulase production could be achieved. The FP (filter paper) activity of 3.7 U/ml and CMCase (Carboxymethylcellulase) activity of 60 U/ml were obtained from shake flask culture. When it was grown in 2.5L fermentor, where pH and DO levels are controlled, the Enzyme activities were 133.35 U/ml (CMCase) and 11.67 U./ml (FP), respectively. Ammonium sulfate precipitation method was used to recover enzymes from fermentation broth. The dried cellulase powder showed 3074.9 U/g of CMCase activity and 166.7 U/g of FP activity with 83.5% CMCase recovery.     

The larva of Eustra (Coleoptera, Paussinae, Ozaenini):a facultative associate of ants

Larvae of the ground beetle genus Eustra Schmidt-Goebel are described and illustrated for the first time and some biological notes are reported. One specimen of an unknown Eustra species was collected while excavating a nest of the ant Pachycondyla javana Mayr, in Taiwan, which is the first report of a paussine associated with a member of the ant subfamily Ponerinae. Several larvae and adults of a second species, Eustra chinensis Bänninger, were collected in Shanghai under bark with no association with ants. First instar larvae of the latter species were also reared in the lab. The occurrence of larvae of the genus Eustra both inside and outside ant nests, together with a report of adults collected inside a nest in Taiwan, suggests that members of this genus may be facultative predators or facultative symbionts of ants, an attribute that has never been reported for this genus. The larvae of Eustra show several unique features, including a peculiar bidentate mandibular apex, an extremely long galea, one of two tarsal claws greatly reduced, abdominal setae (including those of terminal disk) elongate and clavate at apex, urogomphi wide and flattened, and inflated sensilla S-I. Larvae were studied by both optical and scanning electron microscopy, their morphological features are compared with those of other described Paussinae larvae, and their potential phylogenetic and functional significance are discussed.     

Improved curdlan fermentation process based on optimization of dissolved oxygen combined with pH control and metabolic characterization of <Emphasis Type="Italic">Agrobacterium</Emphasis> sp. ATCC 31749

A significant problem in scale-down cultures, rarely studied for metabolic characterization and curdlan-producing Agrobacterium sp. ATCC 31749, is the presence of dissolved oxygen (DO) gradients combined with pH control. Constant DO, between 5% and 75%, was maintained during batch fermentations by manipulating the agitation with PID system. Fermentation, metabolic and kinetic characterization studies were conducted in a scale-down system. The curdlan yield, intracellular nucleotide levels and glucose conversion efficiency into curdlan were significantly affected by DO concentrations. The optimum DO concentrations for curdlan production were 45–60%. The average curdlan yield, curdlan productivity and glucose conversion efficiency into curdlan were enhanced by 80%, 66% and 32%, respectively, compared to that at 15% DO. No apparent difference in the gel strength of the resulting curdlan was detected. The comparison of curdlan biosynthesis and cellular nucleotide levels showed that curdlan production had positive relationship with intracellular levels of UTP, ADP, AMP, NAD⁺, NADH and UDP-glucose. The curdlan productivity under 45% DO and 60% DO was different during 20–50 h. However, after 60 h curdlan productivity of both conditions was similar. On that basis, a simple and reproducible two-stage DO control process for curdlan production was developed. Curdlan production yield reached 42.8 g/l, an increase of 30% compared to that of the single agitation speed control process.     

Enhancement of butanol tolerance and butanol yield in Clostridium acetobutylicum mutant NT642 obtained by nitrogen ion beam implantation

As a promising alternative biofuel, biobutanol can be produced through acetone/butanol/ethanol (ABE) fermentation. Currently, ABE fermentation is still a small-scale industry due to its low production and high input cost. Moreover, butanol toxicity to the Clostridium fermentation host limits the accumulation of butanol in the fermentation broth. The wild-type Clostridium acetobutylicum D64 can only produce about 13 g butanol/L and tolerates less than 2% (v/v) butanol. To improve the tolerance of C. acetobutylicum D64 for enhancing the production of butanol, nitrogen ion beam implantation was employed and finally five mutants with enhanced butanol tolerance were obtained. Among these, the most butanol tolerant mutant C. acetobutylicum NT642 can tolerate above 3% (v/v) butanol while the wide-type strain can only withstand 2% (v/v). In batch fermentation, the production of butanol and ABE yield of C. acetobutylicum NT642 was 15.4 g/L and 22.3 g/L, respectively, which were both higher than those of its parental strain and the other mutants using corn or cassava as substrate. Enhancing butanol tolerance is a great precondition for obtaining a hyper-yield producer. Nitrogen ion beam implantation could be a promising biotechnology to improve butanol tolerance and production of the host strain C. acetobutylicum.     

酱油在贮存过程中偶有用胀袋原因的初步研究

山崎酱油在贮存过程中偶有胀袋,细菌总数超标,继续酸化等问题,怀疑是乳酸菌（Lactobacillus) 在酱油中继续生长引起的。试图[通过本实验阐明乳酸菌在醪中生长和产酸的关系。