Isolation and Identification of a Cellulose-degrading Bac- terium from Paddy Soils in Chengdu City

In this study, a cellulose-degrading bacterium was isolated from paddy soils in Chengdu City. After 2 d of culture, the average diameter of hydrolytic circles on CMC-Congo red medium was 26 -30 mm. Single colonies on LB plates were white and wrinkled. The isolated strain was identified as a Gram-negative bacterium by Gram staining, which could produce short red-like spores. Colony PCR was performed using the bacterial 16S rDNA universal primers. A 1 429 kb DNA fragment was amplified. Based on sequence homology analysis and comprehensive analysis, the isolated strain was identified as Bacillus velezensi, which was named CDBV62 according to the origin.

Screening and Identification of Efficient Cellulose-degrading Strain and Its Preliminary Application in Sheep Dung Compost

The paper was to solve the problems of incomplete fermentation and more cellulose impurities in finished products caused by high cellulose content in sheep dung and accessory substances in composting production.[Method]Efficient cellulose-degrading strains were screened from different animal dung samples and three widely used commercial microbial composting strains(RW,BDM and JBB).The target strains were comprehensively screened by Congo red staining,degradation test of filter strips and cellulase activity test,and the strains screened were identified by physiological and biochemical tests and molecular tests.The strain was used to produce bioaugmentation strain,which was compared with composting fermentation of commercial strains.The temperature of composting process and the physical and chemical properties of finished products were tested to determine whether it met the national standards.[Result]A strain(M2)with strong cellulose-degrading ability from horse dung was screened,and its cellulase activity was(126.06±0.36)U/mL,higher than that of cellulose strain with the highest enzyme activity in commercial strains.Through morphological,physiological and biochemical identification and 16S rDNA sequence analysis,strain M2 was identified as Sphingomonas paucimobilis belonging to Sphingomonas sp.Compared with commercial strains,the bioaugmentation strain effectively improved the cellulose-degrading ability of strains after composting fermentation.The products were uniform in color,without obvious cellulose impurities,and the total nutrients were improved to a certain extent.[Conclusion]The strain M2 screened can be used for the development of specific strain for sheep dung composting.

Effects of Different Proportions of Spent Pleurotus ostreatus Substrate on Seed Germination and Seedling Growth of Mung Beans

[Objectives] This study was conducted to investigate the effects of different proportions of spent Pleurotus ostreatus substrate on the germination and seedling growth of mung beans. [Methods] The cellulose-degrading bacteria HB8 and HF1 were mixed with a commercially available microbial composting agent, respectively, for the composting of spent P. ostreatus substrate. Mung beans were cultivated with different proportions of spent mushroom substrate compost and soil. The seed germination rate, plant height, fresh weight and chlorophyll content of mung bean were used as indicators to investigate the effects of the organic fertilizer from spent P. ostreatus substrate on the growth of mung bean seedlings. [Results] The addition of cellulose-degrading bacteria can significantly improve the composting effect of the spent mushroom substrate. After 8 d of cultivation of mung beans with different ratios of the mushroom substrate organic fertilizer, 50% of the organic fertilizer can make the plant height, fresh weight and leaf chlorophyll content of mung bean seedlings reach the highest value and was suitable for mung bean breeding and cultivation. [Conclusions] This study provides scientific basis and technical indicators for the rapid and harmless treatment of spent mushroom substrate and its application in crop cultivation and nursery.

Screening Psychrophilic Fungi of Cellulose Degradation and Characteristic of Enzyme Production

A fungus（WR-C1） decomposed cellulose was isolated from a hypothermal litter layer using Congo red medium as the preliminary screening culture medium and then using a filter as the secondary screening medium at low temperature. The experiment showed that the weight loss rate of filter paper on the 15 th days could reach 30.69%. A morphologic and ITS gene sequence analysis suggested that CF-C1 was Cladosporium. We mainly studied the effects of culture time, inoculation amount, initial p H and different sources of carbon, nitrogen and inorganic salt on the cellulase production of strain WR-C1. Under optimum cultural condition, the highest value of WR-C1 enzyme production and filter paper enzyme were 3.27 U · m L～（-1） and 0.51 U · m L～（-1）.

Characterization of the effective cellulose degrading strain CTL-6

An efficient cellulose degrading bacteria exists in the thermophilic wheat straw-degrading community, WDC2. However, this strain cannot be isolated and cultured using conventional separation techniques under strict anaerobic conditions. We successfully isolated a strain of effective cellulose degrading bacteria CTL-6 using a wash, heat shock, and solid-liquid alternating process. Analysis of its properties revealed that, although the community containing the strain CTL-6 grew under aerobic conditions, the purified strain CTL-6 only grew under anaerobic culture conditions. The strain CTL-6 had a striking capability of degrading cellulose （80.9% weight loss after 9 days of culture）. The highest efficiency value of the endocellulase （CMCase activity） was 0.404 μmol/（min·mL）, cellulose degradation efficiency by CTL-6 was remarkably high at 50–65°C with the highest degradation efficiency observed at 60°C. The 16S rRNA gene sequence analysis indicated that the closest relative to strain CTL-6 belonged to the genus Clostridium thermocellum. Strain CTL-6 was capable of utilizing cellulose, cellobiose, and glucose. Strain CTL-6 also grew with Sorbitol as the sole carbon source, whereas C. thermocellum is unable to do so.