ABSTRACT
Salvia miltiorrhiza is a perennial herbaceous plant for traditional Chinese medicine. It has been extensively applied for many hundred years to treat various diseases (Su et al. 2015). It is also a kind of important cash crop that is widely cultivated in southern Shaanxi province. In June of 2021, in a field in Luonan County, Shaanxi Province, some S. miltiorrhiza plants with stunting and leaf wilting symptoms were observed. The diseased plants exhibited a large number of globular galling on the secondary and tertiary roots. The symptoms were typical of infection by root-knot nematodes. Population densities of second-stage juveniles (J2s) ranged from 330 to 650 per 100 cm3. To identify the species of the root-knot nematodes, J2s and males were collected from the soil in the root zone, and females were isolated from diseased roots. The perineal patterns of females (n = 12) were round-shaped, with low dorsal arches, obvious lateral lines, and characteristic small punctations near anus. Morphological measurements of females (n = 20) included body length (L) = 565.25 ± 33.9 (503.35 - 632.47) µm, body width (BW) = 420.00 ± 21.28 (378.27 - 452.51) µm, stylet = 11.11 ± 0.73 (10.05-12.29) µm, dorsal pharyngeal gland orifice to stylet base (DGO) = 4.69 ± 0.45 (3.82-5.32) µm, vulval slit length = 21.1 ± 1.33 (18.38-22.96) µm, and vulval slit to anus distance = 15.76 ± 1.24 (13.38-17.45) µm. The morphological characters of males (n = 7): L = 1098.14 ± 82.99 (962.83-1193.87) µm, BW = 28.44 ± 1.18 (26.59-29.83) µm, stylet = 18.27 ± 0.97 (16.57-19.28) µm, DGO = 4.89 ± 0.62 (3.82-5.68) µm, and spicule length = 24.04 ± 1.80 (21.30-26.71) µm. The key morphometrics of J2s: L = 380.24 ± 18.24 (354.43-423.13) µm, BW = 13.94 ± 0.70 (12.88-15.34) µm, stylet = 11.82 ± 0.49 (10.96-12.61) µm, DGO = 3.68 ± 0.42 (3.09-4.56) µm, tail length = 55.42 ± 5.81 (46.97-67.03) µm, and hyaline tail terminus = 13.79 ± 1.24 (12.0-16.51) µm. These morphological characteristics are consistent with Meloidogyne hapla as described by Whitehead (1968). Ten individual females were transferred to ten different tubes for DNA extraction. The DNA extraction followed the method described by Htay et al. (2016). The species-specific primers JMV1 (5'-GGATGGCGTGCTTTCAAC-3') and JMV (5'-AAAAATCCCCTCGAAAAATCCACC-3') were used for the identification of M. hapla (Adam et al. 2007). A single 440 bp fragment was amplified by this pair of primers, confirming their identities as M. hapla. To confirm species identification, the ITS region was amplified using the primers 18S/26S (5'-TTGATTACGTCCCTGCCCTTT-3'/5'-TTTCACTCGCCGTTACTAAGG-3') (Vrain et al. 1992). The sequence from the ITS region was 768 bp (GenBank Accession No. OM049198) and was 100% identical to the sequences of M. hapla (GenBank Accession Nos. MT249016 and KJ572385). The mitochondrial DNA (mtDNA) region between COII and the lRNA gene was amplified using primers C2F3 (5'-GGTCAATGTTCAGAAATTTGTGG-3') and 1108 (5'-TACCTTTGACCAATCACGCT-3') (Powers and Harris, 1993). A fragment of 529 bp was obtained and the sequence (GenBank Accession No. OM055828) was 100% identical to the known sequence of M. hapla from Taiwan (GenBank Accession No. KJ598134). An infection test was conducted in greenhouse conditions. Six 2-month-old S. miltiorrhiza plants were individually maintained in 12-cm diameter, 10-cm deep plastic pots containing sterilized soil and each plant was inoculated with 3000 J2s hatched from egg masses of collected M. hapla samples. Two non-inoculated S. miltiorrhiza plants served as negative controls. After 60 days, inoculated plants exhibited galled roots similar to those observed in the field. Many galls (61.33 ± 8.52) and egg masses (26.17 ± 4.79) were found on each root system. The nematode reproduction factor (RF = final population/initial population) was 4.5. No symptoms were observed in control plants. The nematode was reisolated from root tissue and identified to be M. hapla with its sequence-specific primers JMV1/JMV. These results confirmed that the nematode population could infect S. miltiorrhiza. To our knowledge, this is the first time of natural infection of S. miltiorrhiza with M. hapla in China. Including S. miltiorrhiza, the medicinal ingredients of many traditional Chinese herbal medicines were extracted from the roots of the plants. The infection of root-knot nematode will cause a serious decline in the quality of Chinese medicinal materials. Therefore, it is necessary to identify the species of root-knot nematode in different Chinese herbal medicines.
ABSTRACT
BACKGROUND: Environmental issues, such as the fossil energy crisis, have resulted in increased public attention to use bioethanol as an alternative renewable energy. For ethanol production, water and nutrient consumption has become increasingly important factors being considered by the bioethanol industry as reducing the consumption of these resources would decrease the overall cost of ethanol production. Biogas slurry contains not only large amounts of wastewater, but also the nutrients required for microbial growth, e.g., nitrogen, ammonia, phosphate, and potassium. Therefore, biogas slurry is an attractive potential resource for bioethanol production that could serve as an alternative to process water and nitrogen sources. RESULTS: In this study, we propose a method that replaces the process water and nitrogen sources needed for cellulosic ethanol production by Zymomonas mobilis with biogas slurry. To test the efficacy of these methods, corn straw degradation following pretreatment with diluted NaOH and enzymatic hydrolysis in the absence of fresh water was evaluated. Then, ethanol fermentation using the ethanologenic bacterial strain Z. mobilis ZMT2 was conducted without supplementing with additional nitrogen sources. After pretreatment with 1.34% NaOH (w/v) diluted in 100% biogas slurry and continuous enzymatic hydrolysis for 144 h, 29.19 g/L glucose and 12.76 g/L xylose were generated from 30 g dry corn straw. The maximum ethanol concentration acquired was 13.75 g/L, which was a yield of 72.63% ethanol from the hydrolysate medium. Nearly 94.87% of the ammonia nitrogen was depleted and no nitrate nitrogen remained after ethanol fermentation. The use of biogas slurry as an alternative to process water and nitrogen sources may decrease the cost of cellulosic ethanol production by 10.0-20.0%. By combining pretreatment with NaOH diluted in biogas slurry, enzymatic hydrolysis, and ethanol fermentation, 56.3 kg of ethanol was produced by Z. mobilis ZMT-2 through fermentation of 1000 kg of dried corn straw. CONCLUSIONS: In this study, biogas slurry replaced process water and nitrogen sources during cellulosic ethanol production. The results suggest that biogas slurry is a potential alternative to water when pretreating corn straw and, thus, has important potential applications in cellulosic ethanol production from corn straw. This study not only provides a novel method for utilizing biogas slurry, but also demonstrates a means of reducing the overall cost of cellulosic ethanol.
ABSTRACT
OBJECTIVE: To apply the classic leakage integrate-and-fire models, based on the mechanism of the generation of physiological auditory stimulation, in the information processing coding of cochlear implants to improve the auditory result. METHODS: The results of algorithm simulation in digital signal processor (DSP) were imported into Matlab for a comparative analysis. RESULTS: Compared with CIS coding, the algorithm of membrane potential integrate-and-fire (MPIF) allowed more natural pulse discharge in a pseudo-random manner to better fit the physiological structures. CONCLUSION: The MPIF algorithm can effectively solve the problem of the dynamic structure of the delivered auditory information sequence issued in the auditory center and allowed integration of the stimulating pulses and time coding to ensure the coherence and relevance of the stimulating pulse time.