Purification of an Aspergillus oryzae Metallo-proteinase by Talopeptin-aminohexyl-Sepharose and Its Properties

Simple and speedy purification of Aspergillus oryzae metallo-proteinase was performed using Talopeptin-aminohexyl-Sepharose The properties of the metallo-proteinase were: optimum pH 6.5; pH stability, pH 5~11; optimum temperature,50°C; and molecular weight 42,000 (SDS electrophoresis). These results were similar to those of neutral protease I from Aspergillus oryzae reported by Nakadai et al. This metallo-proteinase was compared with others from microbes using the metallo-proteinase inhibitors FMPI, PLT, and Talopeptin. The metallo-proteinase is unique in the point at which FMPI and PLT gave nearly stoichiometrical inhibition.     

Isolation and Identification of Microorganism,Producing Microbial Alkaline Proteinase Inhibitor (MAPI)

In the screening of actinomycetes’ culture filtrate for inhibitor of subtilisin and various microbial alkaline proteinases, a novel inhibitor was found in a cultured broth of strain WT-27. This inhibitor was named as MAPI, abbreviation of microbial alkaline proteinase inhibitor.Judging from the morphological and physiological properties of the actinomycetes which produced MAPI, this strain was identified as Streptomyces nigrescens.

For the production of MAPI, this strain was aerobically cultured at 25 ~ 27%C in a jar fermentor which contained an optimum medium consisting of polypepton 3 %, meat extract 1%, glucose 1%, NaCl 0.1%, K₂HPO₄ 0.1% and MnSO₄·nH₂O 0.0001%, pH 7.0. The production of MAPI reached its maximum after 21 ~ 24 hr cultivation.

MAPI had an inhibitory activity against various microbial alkaline proteinases, α-chymotrypsin and papain but not against trypsin, kallikrein, thermolysin, or pepsin.     

Isolation and Identification of a Hog Pancreatic α-Amylase Inhibitor (Haim) Producing Streptomyces

A screening test was carried out to obtain microbes which produce hog pancreatic α-amylase inhibitor and a new inhibitor was found in culture broth of an actinomycete, strain YM-25. This inhibitor was designated as Haim, an abbreviation for hog pancreatic α-amylase inhibitor from a microbe. The determined morphological and physiological properties of strain YM-25 led to the conclusion that the microorganism was Streptomyces griseosporeus.

When the microorganism was aerobically cultured at 30°C in a jar fermentor containing the most suitable medium for growth which consisted of 5% glycerol, 0.5% polypepton, 0.2% meat extract, 0.1% yeast extract, 0.4% Na₂HPO₄ ? 12H₂O, 0.1% KH₂PO₄, and 0.05% MgSO₄ ? 7H₂O (pH 7.3), the highest activity of Haim was obtained on 23~26hr cultivation.

Haim had specific inhibitory activities against animal α-amylases but not against microbial and plant α-amylases.     

Lipoxygenase inhibition by novel fatty acid ester from Annona squamosa seeds

Studies on the seeds of Annona squamosa yielded a novel lipoxygenase inhibitor fatty acid ester, (+) - annonlipoxy (1). Compound 1 was screened for its enzyme inhibitory activity against lipoxygenase (E.C.1.14.18.1), exhibiting activity with IC₅₀ 69.05 ± 5.06 μm. Baicalein (IC₅₀ 22.6 ± 0.5 μm) was used as a positive control. Crude extracts of Annona squamosa fruit pulp and seeds were screened for its enzyme inhibitory activity against lipoxygenase and acetylcholinesterase. The crude ethanolic extract of fruit pulp and seeds of Annona squamosa also exhibited lipoxygenase activity with 22.2 and 26.7% inhibition, while the pet.ether extract of seeds of A. squamosa exhibited 52.7% inhibition at a concentration of 40 μg/200 ml. The crude ethanolic extract of seeds of Annona squamosa was also bioassayed for acetylcholinesterase inhibition and it was found inactive.     

Antimutagenic activity of Lactobacillus plantarum KLAB21 isolated from kimchi Korean fermented vegetables

Antimutagenic activity of Lactobacillus plantarum KLAB21, isolated from Korean kimchi, was investigated against MNNG (N-methyl-N-nitro-N-nitrosoguanidine), NQO (4-nitroquinoline-1-oxide), NPD (4-nitro-O-phenylenediamine) and aflatoxin B1 using Salmonella typhimurium strains TA100 and TA98. Although all the cell fractions including the culture supernatant, dry cells and cell-free extract exhibited antimutagenic activity against MNNG and NQO, the culture supernatant possessed the highest activity. The antimutagenic ratio of the culture supernatant was 98.4% against MNNG on strain TA100 and 57.3% against NQO on strain TA98. Its antimutagenic activity was reconfirmed by a Bacillus subtilis spore-rec assay. Levels of the antimutagenic ratios of other lactic acid bacteria originating from fermented milk ranged between 26.8 to 53% against MNNG and 28.5 to 43.4% against NQO. The antimutagenic activities of the strain KLAB21 against NPD were 72.6% on TA100 and 62.8% on TA98, and those against aflatoxin B1 were 82.5% on TA100 and 78.2% on TA98.     

Purification,characterization and evaluation of insecticidal potential of trypsin inhibitor from mungbean (<Emphasis Type="Italic">Vigna radiata</Emphasis> L. Wilczek) seeds

Protease inhibitors present in seeds of legumes possess strong inhibitory activity against trypsin and confer resistance against pests. In the present investigation, trypsin inhibitor activity was found in the seed flour extracts of all the eight selected varieties of mungbean under study which was further confirmed by dot blot analysis. All the varieties showed inhibitory activity in vitro against the gut protease of Helicoverpa armigera (HGP). Trypsin inhibitor was purified from mungbean seeds to near homogeneity with 58.1-fold and 22.8% recovery using heat denaturation, NH₄(SO₄)₂ fractionation, ion-exchange chromatography on DEAE-Sephadex A-25 and gel filtration through Sephadex G-75. The molecular mass of the inhibitor was 47 kDa as determined by gel filtration and SDS-PAGE. The inhibitor retained 90% or more activity between pH 4 and 10, however, it was nearly inactive at extreme pH values. The inhibitor was stable up to 80°C but thereafter, the activity decreased gradually retaining nearly 30% of activity when heated at 100°C for 20 min. The inhibitor activity was undetectable at 121°C. Insect bioassay experiment using purified mungbean trypsin inhibitor showed a marked decline in survival (%) of larvae with increase in inhibitor concentration. The larval growth was also extended by the trypsin inhibitor. This study signifies the insecticidal potential of mungbean trypsin inhibitor which might be exploited for raising transgenic plants.     

Identification of new benzamide inhibitor against α-subunit of tryptophan synthase from Mycobacterium tuberculosis through structure-based virtual screening,anti-tuberculosis activity and molecular dynamics simulations

Multi-drug-resistant tuberculosis and extensively drug-resistant tuberculosis has emerged as global health threat, causing millions of deaths worldwide. Identification of new drug candidates for tuberculosis (TB) by targeting novel and less explored protein targets will be invaluable for antituberculosis drug discovery. We performed structure-based virtual screening of eMolecules database against a homology model of relatively unexplored protein target: the α-subunit of tryptophan synthase (α-TRPS) from Mycobacterium tuberculosis essential for bacterial survival. Based on physiochemical properties analysis and molecular docking, the seven candidate compounds were selected and evaluated through whole cell-based activity against the H37Rv strain of M. tuberculosis. A new Benzamide inhibitor against α-subunit of tryptophan synthase (α-TRPS) from M. tuberculosis has been identified causing 100% growth inhibition at 25 μg/ml and visible bactericidal activity at 6 μg/ml. This benzamide inhibitor displayed a good predicted binding score (?48.24 kcal/mol) with the α-TRPS binding pocket and has logP value (2.95) comparable to Rifampicin. Further refinement of docking results and evaluation of inhibitor-protein complex stability were investigated through Molecular dynamic (MD) simulations studies. Following MD simulations, Root mean square deviation, Root mean square fluctuation and secondary structure analysis confirmed that protein did not unfold and ligand stayed inside the active pocket of protein during the explored time scale. This identified benzamide inhibitor against the α-subunit of TRPS from M. tuberculosis could be considered as candidate for drug discovery against TB and will be further evaluated for enzyme-based inhibition in future studies.     

PepJ is a new extracellular proteinase of <Emphasis Type="Italic">Aspergillus nidulans</Emphasis>

Under carbon starvation, Aspergillus nidulans released a metallo-proteinase with activities comparable to those of PrtA, the major extracellular serine proteinase of the fungus. The relative molar mass of the enzyme was 19 kDa as determined with both denaturing and renaturing SDS PAGE, while its isoelectric point and pH and temperature optima were 8.6, 5.5 and 65 °C, respectively. The enzyme was stable at pH 3.5–10.5 and was still active at 95 °C in the presence of azocasein substrate. MALDI-TOF MS analysis demonstrated that the proteinase was encoded by the pepJ gene (locus ID AN7962.3), and showed high similarity to deuterolysin from Aspergillus oryzae. The size of the mature enzyme, its EDTA sensitivity and heat stability also supported the view that A. nidulans PepJ is a deuterolysin-type metallo-proteinase.     

Discovery and characterization of Sip1A: a novel secreted protein from Bacillus thuringiensis with activity against coleopteran larvae

Bioassay screening of Bacillus thuringiensis culture supernatants identified strain EG2158 as having larvicidal activity against Colorado potato beetle (Leptinotarsa decemlineata) larvae. Ion-exchange fractionation of the EG2158 culture supernatant resulted in the identification of a protein designated Sip1A (secreted insecticidal protein) of approximately 38 kDa having activity against Colorado potato beetle (CPB). An oligonucleotide probe based on the N-terminal sequence of the purified Sip1A protein was used to isolate the sip1A gene. The sequence of the Sip1A protein, as deduced from the sequence of the cloned sip1A gene, contained 367 residues (41,492 Da). Recombinant B. thuringiensis and Escherichia coli harboring cloned sip1A produced Sip1A protein which had insecticidal activity against larvae of CPB, southern corn rootworm (Diabrotica undecimpunctata howardi), and western corn rootworm (Diabrotica virgifera virgifera).     

Cloning and Expression of the Insecticidal Crystal Protein Gene <Emphasis Type="Italic">Cry</Emphasis>1Ca9 of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> G10-01A from Taiwan Granaries

A new cry gene (cry1Ca9) was cloned and sequenced from a Bacillus thuringiensis isolate native to Taiwan (G10-01A). The cry1C-type gene, designated cry1Ca9, consisted of an open reading frame of 3,567 bp, encoding a protein of 1,189 amino acid residues. The polypeptide has the deduced amino acid sequences predicting molecular masses of 134.7 kDa. The gene sequence was compared against the GenBank nucleotide sequence data base. It was found that the cry1Ca9 gene coded for a 134.7-kDa protoxin which had greater than 99.8% homology with the previously reported cry1Ca1 gene, as only three mismatches were found between the two amino acid sequences. When the Cry1Ca9 toxin was expressed in a crystal-negative strain of B. thuringiensis (cryB^-), elliptical crystals were produced. Cell extracts from this recombinant strain appear to have high insecticidal activity against lepidopteran larvae (Plutella xylostella).Received: 23 September 2002 / Accepted: 6 December 2002     

Revelation of Antiviral Activities by Artificial Sulfation of a Glycosaminoglycan from a Marine Pseudomonas

Sulfated derivatives of a glycosaminoglycan containing l-glutamic acid produced by a marine Pseudomonas species, No. 42 strain, were prepared by the method of dicyclohexyl-carbodiimide-mediated reaction. Both low and high degrees of sulfation of the polysaccharides (products A1 and A2, respectively) were investigated for their antiviral activities against influenza virus type A (FluV-A) and B (FluV-B) in MDCK cells. Both preparations showed antiviral activity against FluV-A at the 50% antiviral effective concentration of 17.3 and 5.2 μg/ml, respectively, whereas they had no antiviral activity against FluV-B. No cytotoxicity of either product was noted against MDCK cells at the 50% cytotoxic concentration of 100 μg/ml. Received April 4, 1998; accepted July 24, 1998.     

Characterization of proteolytic activities of rumen bacterial isolates from forage-fed cattle

The proteolytic activities of eight strains of ruminal bacteria isolated from New Zealand cattle were characterized with respect to their cellular location, response to proteinase inhibitors and hydrolysis of artificial proteinase substrates. The Streptococcus bovis strains had predominantly cell-bound activity, which included a mixture of serine and cysteine-type proteinases which had high activity against leucine p -nitroanilide (LPNA). The Eubacterium strains had a mainly cell-associated activity with serine and metallo-type proteinases which showed high activity against the chymotrypsin substrate, N -succinyl alanine alanine phenylalanine proline p -nitroanilide (NSAAPPPNA) and some LPNA activity. A Butyrivibrio strain, C211, had a cell-bound mixture of cysteine and metallo-proteinase activities and strongly hydrolysed NSAAPPPNA and LPNA while the high activity Butyrivibrio -like strain, B316, had a cell-bound, mainly serine proteinase activity which strongly hydrolysed NSAAPPPNA. A Prevotella -like strain, C21a, had a mixture of cysteine, serine and metallo-proteinase activities which were cell-bound and hydrolysed LPNA. The activities of these strains did not match those of the bacterial fraction of rumen fluid, which contained activities mainly of the cysteine type with specificity towards the substrate N -succinyl phenylalanine p -nitroanilide. The contribution of these strains to proteolysis in the rumen is discussed.     

Altitudinal Variation In Phase Response Curves For The Himalayan Strains Of Drosophila Helvetica

In previous research, it was determined that the altitude of origin altered the parameters of photic entrainment and free‐running rhythmicity of adult locomotor activity of the high‐altitude Himalayan (haH) strain (Hemkund‐Sahib, 4121 m above sea level) of Drosophila helvetica compared to the low‐altitude Himalayan (laH) strain (Birahi, 1132 m above sea level) of the same species. The present study investigated whether the altitude of origin also affects the parameters of the light pulse phase response curve (PRC) of the adult locomotor activity rhythm of the haH strain. Light pulse PRCs were determined for both strains against the background of constant darkness. Although both were “weak” or type 1 PRCs, the PRC for the haH strain differed from that of the laH strain in three basic parameters. The PRC for the haH strain was of low amplitude, had a protracted dead zone, and showed a ratio of the advance to delay region (A/D>1), while the PRC of the laH strain was characterized by high amplitude, absence of dead zone, and a A/D ratio<1. The asymmetric PRCs of these strains might explain the process of photic entrainment to 24 h light‐dark cycles, as the long period of the free‐running rhythm (τ) of the haH strain is complemented with a larger advance portion of its PRC (A/D>1), whereas the short τ of the laH strain is matched with a larger delay portion of its PRC (A/D<1). Prolonged dead zone and low amplitude in the PRC of the haH strain imply that the photic sensitivity of this strain has been drastically diminished as an adaptation to environmental conditions at the altitude of its origin. While adults of this strain begin activity in very bright light in the forenoon due to non‐permissible low temperature in the morning, the converse is true for the laH strain.     

Isolation and characterization of Bacillus subtilis KS1 for the biocontrol of grapevine fungal diseases

Bacillus subtilis KS1 was isolated from grape berry skin as a biological control agent against grapevine fungal diseases. KS1 was identified as a new strain of B. subtilis according to morphological, biochemical, and genetic analyses. In vitro bioassay demonstrated that KS1 suppressed the growth of Botrytis cinerea (the casual agent of grape grey mold) and Colletotrichum gloeosporioides (the casual agent of grape ripe rot). The biocontrol activity of KS1 against grapevine fungal diseases in vineyards was evaluated over a 3-year span (from 2007 to 2009). Downy mildew, caused by Plasmopara viticola, was reduced on berry skins and leaves by treatment with KS1. The KS1 genome possesses ituD and lpa-14 genes, both of which play a role in iturin A production followed by iturin A production in the culture. In contrast, mutants lacking both genes lost the antagonistic activity against B. cinerea and C. gloeosporioides and the activity in iturin A production, suggesting that the antagonistic activity of KS1 against grapevine fungal pathogens may depend on iturin A production. As KS1 showed tolerance to various chemical pesticides, chemical pesticides could be applied before and/or after KS1 treatment in vineyards. Due to its potential as a biological control agent against grape downy mildew, KS1 is expected to contribute to the further improvement of integrated pest management systems and to potentially reduce the amount of chemical fungicides applied in vineyards.     

Antagonistic and antimicrobial activities of some bacterial isolates collected from soil samples

Thirty seven bacterial cultures isolated from soil samples obtained from different locations were tested for their antagonistic activity against some fungal pathogens, viz., Sclerotium rolfsii, Fusarium oxysporum and Rhizoctonia solani, causal agents of collar rot of sunflower, wilts and root rots, respectively. Among them, 5 bacterial strains, viz., A1 6 (Bacillus sphaericus), K1 24 (Pseudomonas fluorescens), M1 42 (Bacillus circulans), M1 66 (Bacillus brevis) and T1 22 (Bacillus brevis) showed positive antagonistic activity. M1 66 was the most effective in inhibiting mycelial growth of S. rolfsii in vitro followed by M1 42, T1 22, K1 24 and A1 6. Only one bacterial strain i.e. M1 42 exhibited antagonistic activity against F. oxysporum, and none of the bacterial strains gave positive activity against R. solani. Furthermore, antimicrobial activities of all the 5 strains were checked against different test organisms. These strains showed their extensive inhibition effect particularly against gram-positive test bacteria (Staphylococcus aureus and Bacillus subtilis) and the test fungal strain (Candida albicans). On the other hand, B. brevis M1 66 and B. brevis T1 22 strains had an inhibitory effect against gram positive and gram-negative test bacteria (Escherichia coli and Proteus vulgaris) as well as the test fungal strain.     

A Convenient Method for Rapid Determination of Cereal Proteins: A Device to Eliminate the Effect of Color Substances on the Biuret Procedure

At least, four kinds of amylase inhibitors are found in culture of Streptomyces sp. No.280.¹⁾ A large amount of amylase inhibitors were produced by Streptomyces sp. No. 280 when cultivated on 3% oatmeal medium and it was found that the molecular weight of the inhibitors were transformed to smaller molecules during the cultivation time. The transformation of the amylase inhibitor was found to result from degradation of its carbohydrate moiety by α-amylase in the culture broth. The amylase inhibitor was hydrolyzed partially by the action of taka-amylase A or hog pancreatic α-amylase. With hydrolyzation of amylase inhibitor by α-amylase, neutral sugars (mainly maltose) were liberated from the amylase inhibitor and a modified inhibitor was newly formed, but amylase inhibitory activity against glucoamylase was not changed. The inhibitory activity against muscle Phosphorylase a, however, was almost completely lost.     

CELL-ASSOCIATED PROTEOLYTIC ENZYMES FROM MARINE PHYTOPLANKTON1

Despite their central importance in cell metabolism, little is known about proteases in marine phytoplankton. We surveyed caseinolytic and leucine aminopeptidase (LAP) activities in log-phase cultures of the chlorophyte Dunaliella tertiolecta Butcher, the diatom Thalassiosira weissflogii (Gru.) Fryxell et Hasle, the chrysophyte Isochrysis galbana Parke, the coccolithophorid Emiliania huxleyi (Lohm.) Hay et Mohler, and the cyanobacterium Synechococcus sp. (WH 5701). LAP activity was very low at pH < 6 and peaked between pH 7.5 and 8.5 in all species, whereas caseinolytic activity in most species showed only minor peaks in the pH 4–5 range and broad maxima above pH 8. Thus, acidic vacuolar proteases apparently represented only a small fraction of total protease activity. Attempts to classify proteases using selective inhibitors were inconclusive. Neither the serine/cysteine protease inhibitor leupeptin nor the aspartic protease inhibitor pepstatin. A inhibited caseinolytic or LAP activity in any species. The metalloprotease inhibitor EDTA was only effective against LAP activity in some species, causing average decreases of 30–50%, whereas the cysteine/serine protease inhibitor phenyl methyl sulfonylfluoride achieved at best a 30–60% decrease in caseinolytic activity. Caseinolytic activities were remarkably stable. At pH 7.5 and 25°C, extracts of D. tertiolecta, E. huxleyi, and Synechococcus showed no changes in activity after 24 h, whereas activity declined by less than 50% in the other species. Incubation of cell extracts for 1 h at 25°C in pH 7.5 buffer did not alter patterns of cell proteins, suggesting that endogenous proteases did not effectively degrade endogenous proteins. Casein zymograms were used to identify >200-and <20-kDa proteases in homogenates of log-phase T. weissflogii; only the smaller protease was found in D. tertiolecta. Antibodies to the ATPase subunit (C) of the conserved, chloroplastic Clp protease from Pisum cross-reacted with proteins in Synechococcus, D. tertiolecta, and I. galbana, but no cross-reactions were found for any species with antibodies against the ClpP subunit from either E. coli or Nicotiana. Our results show that phytoplankton contain a diverse complement of proteases with novel characteristics.     

Identification and partial characterization of tochicin, a bacteriocin produced by Bacillus thuringiensis subsp tochigiensis

Bacillus thuringiensis subsp tochigiensis HD868 was identified as a bacteriocin producer which exhibited a bactericidal effect against closely related species. This bacteriocin designated as tochicin, was partially purified by 75% ammonium sulfate precipitation followed by subsequent dialysis. This partially purified tochicin showed a narrow antibacterial spectrum of activity against most of 20 typical B. thuringiensis strains and a strain of B. cereus, but not against other bacteria and yeasts tested. The antibacterial activity of tochicin on sensitive indicator cells disappeared completely by proteinase K treatment (1 mg ml⁻¹), which indicates its proteinaceous nature. Tochicin was very stable throughout the range of pH 3.0–9.0 and was relatively heat-stable at 90°C, but bacteriocin activity was not detected after boiling for 30 min. The relationship between cell growth and bacteriocin production was studied in a semi-defined medium. Tochicin activity was detected at the mid-log growth phase, reached the maximum at the early stationary phase, but decreased after the stationary phase. Direct detection of tochicin activity on sodium dodecyl sulfate-polyacrylamide gel suggested it has an apparent molecular mass of about 10.5 kDa. Tochicin exhibited a bactericidal activity against B. thuringiensis subsp thompsoni HD522 in phosphate buffer (pH 7.0). Received 02 December 1996/ Accepted in revised form 25 August 1997     

An in vitro method for increasing UV-tolerance in a strain of Helicoverpa armigera (Lepidoptera: Noctuidae) nucleopolyhedrovirus

A method for increasing tolerance to ultraviolet (UV) radiation in a strain of nucleopolyhedrovirus of cotton bollworm, Helicoverpa armigera (Hübner) (HearNPV) using a solar simulator is described. The Coimbatore isolate (CBE I) of HearNPV was subjected to a five-step sequence of selection to increase its UV tolerance. Each step consisted of irradiation of wet deposits of the virus to near UV (at energy level of 300W/m²), bioassay against second instar H. armigera larvae and propagation in early fifth instar larvae. Selection steps carried out at 15, 30, 60 and 90 minutes of exposure revealed that the continuous exposure of HearNPV-CBE I at low doses of UV irradiation (270–540 KJ/m²) did not significantly affect the virus activity as measured by its biological activity against second instar larvae. Selection at higher doses (1620 KJ/m²) led to loss of viral activity in the first two exposure cycles; however, there was retention of virulence coupled with increased tolerance to UV doses from third cycle onwards. Further, studies on the persistence of UV tolerant strain of HearNPV-CBE I in comparison with original strain showed that the tolerant strain had more persistence even after 7 days of weathering both under exposed (18% original activity remaining) and shaded (26% original activity remaining) condition on potted cotton plant.     

新一代糖化酶高产菌株的选育及其工业应用

【目的】建立对糖化酶生产菌种黑曲霉随机突变文库进行筛选的方法,以获得糖化酶酶活提高的突变菌株。【方法】以一株可产糖化酶的黑曲霉菌株Aspergillus niger X1为出发菌株,经硫酸二乙酯诱变获得突变文库,采用葡萄糖的结构类似物——2-脱氧葡萄糖进行筛选,并在筛选过程中逐渐提高2-脱氧葡萄糖浓度,定向选育具有2-脱氧葡萄糖抗性、高产糖化酶的突变株。【结果】获得的高产突变菌株DG36摇瓶发酵糖化酶产量比出发菌株A.niger X1提高22.2%–33.8%,经工业水平50 m~3罐发酵测试,突变株DG36发酵128 h糖化酶活可达49094 U/m L,在相同发酵时间内,其酶活较出发菌株A.niger X1提高32.8%,发酵时间缩短16.9%。【结论】本研究开发了一种以2-脱氧葡萄糖为抗性标记选育高产糖化酶突变株的方法,所得突变株DG36遗传性状稳定,与出发菌相比具有菌丝粗壮、产酶期提前、糖化酶活高、发酵时间短、有利于发酵后处理的优点。