Effect of inoculation with Penicillium expansum on the microbial community and maturity of compost.

Compost prepared from wheat straw and cattle/chicken mature was inoculated with the lignocellulolytic fungus, Penicillium expansum. Compared to uninoculated compost, the inoculated compost exhibited a 150% higher germination index, more than 1.2 g kg(-1)-dw of changes in NH(4)(+)-N concentrations, a ca. 12.0% higher humus content and a lignocellulose degradation that proceeded 57.5% faster. Culture-based determinations of microbial populations demonstrated that aerobic heterotrophic bacteria and fungi were about 1-2 orders of magnitude higher in inoculated than in uninoculated compost. The number of ammonifying, ammonium-oxidizing, nitrite-oxidizing, denitrifying bacteria and cellulose-decomposing bacteria was 6.1-9.0 log(10) CFU g(-1)-dw, 1.2-4.3 log(10) MPN g(-1)-dw, 3.5-6.8 log(10) MPN g(-1)-dw, 3.58-4.34 log(10) MPN g(-1)-dw, 1.4-3.8 log(10)MPN g(-1)-dw, and 4.2-8.8 log(10) CFU g(-1)-dw higher in the compost inoculated with P. expansum.

Effects of rhamnolipid on the cellulase and xylanase in hydrolysis of wheat straw.

The effects of biosurfactant rhamnolipid (RL) and chemical surfactant Triton X-100 on the production of cellulases and xylanase from Penicillium expansum (P. expansum) in untreated, acid- and alkali-pretreated wheat straw submerged fermentations were studied, and the influences on the activity and stability of Cellulase R-10 were also investigated. The results showed that RL and Triton X-100 enhanced the activities of cellulases and xylanase to different extents and the stimulatory effects of RL were superior to those of Triton X-100. During the peak enzyme production phase, RL (60 RE mg/l) increased cellulases activities by 25.5-102.9%, in which the raise of the same enzyme in acid-pretreated straw broths was the most. It was found that the reducing sugars by hydrolyzing wheat straw with Cellulase R-100 were not visibly increased after adding RL. However, it distinctly protected Cellulase R-10 from degradation or inactivation, keeping the reducing sugars yield at about 17%.

[Isolation and identification of a cellulose degrading fungus Y5 and its capability of degradating wheat straw].

In order to promote the decomposition of crop straw and return it to soil rapidly and solve the problems such as the waste of straw resources and pollution, we screened the bacterial or fungi with high-efficient degradation of straw lignocelluloses and studied its capability of degradating wheat straw. An isolate of filamentous fungus with higher cellulase activity and ability to decompose CMC and straw lignocellulose was screened from black soil samples taken from Heilongjiang province by using the soil dilution, plating and liquid culture methods. Morphological status on various media, and ITS rDNA sequences homology analysis were performed to identify the taxonomy of the isolate. The effects of different time, different N resources, different cellulose resources and different pH values on enzyme activities produced by fungus was analyzed, and The ability of wheat straw degradation of Y5 was determinated by using weight loss method and liquid culture. The fungus was identified as Penicillium ochrochloron and named Y5. Filter paper activity (FPA) and endo-1,4-beta-D-glucanase (EG) were both reached the maximum after the first fourth day inoculated, averaged 53 IU/mL and 55 IU/mL, respectively, which were 22.6% and 18.2% higher than that of strain Trichoderma viride (AS3. 3711), respectively. Enzyme activities were the highest under the condition of wheat straw used as C resources, which were 27.5% and 24.8% higher than that of AS3. 3711. The FPA and EG activities were 35.7% and 14.9% higher than the AS3. 3711 strain with NaNO3 as nitrogen source. The optimal pH value of liquid culture was 6. The cellulose, hemicellulose and lignin contents were degraded by 43.5%, 49.7% and 9.3% after the first 10 days inoculated, respectively, which indicated that Y5 had strong enzyme activities on degradation of cellulose and hemicelluloses of wheat straw. The Penicillium ochrochloron Y5 has strong ability of wheat straw cellulose degradation, and its cellulase activities are higher than some published researches. The Penicillium ochrochloron Y5 strain has the great potential in research and development for inoculant of crop straw decomposition.

[Isolation, identification of a pyrene-degrading strain Mycobacterium sp. M11 and its degrading characteristics].

A bacterial strain M11 using phenanthrene, anthracene, fluorethene,pyrene as a sole carbon and energy sources was isolated from soils contaminated with polycyclic aromatic hydrocarbons. Strain M11 was identified as Mycobacterium sp. according to the results of morphology, physiology and the phylogenetical analyses of 16S rDNA sequence. The degradation rate of pyrene (at levels of 50 mg/L, 100 mg/L and 200 mg/L) by strain M11 was 76.9%, 91.8% and 79.23% within 16 d in broth assay. Mycobacterium sp. M11 showed a strong ability to grow from pH 5 to pH 9 in liquid minimal medium containing pyrene 100 mg/L. Mycobacterium sp. M11 possessed aromatic-ring dioxygenase genes, which are highly homologous to the known nidAB genes from pyrene-degrading Mycobacteria.

[Screening of two phenanthrene-utilizing and high-effective phosphorus-accumulating bacteria and their effects on phosphorus-accumulating characteristics].

In this study, two phenanthrene-utilizing and high-effective P-accumulating bacteria Y11 and Y4-2 were isolated from sludge samples of Taihu Lake using plate culture and blue-colored colonies methods. Strains Y11 and Y4-2 were identified as Acinetobacter sp. according to the results of morphology, physiology and the phylogenetical analyses of 16S rDNA sequences. The two strains showed high effective P-accumulating ability in plate and broth cultures. Y11 could grow well from 10 degrees C to 35 degrees C and pH from 6 to 9, Y4-2 could grow well from 10 degrees C to 35 degrees C and pH from 6 to 8. Phenanthrene could be used as sole carbon and energy sources. In our experiment, high phosphorus concentration in broth culture had no negative effect on the growth of strain Y11, however the growth of strain Y4-2 was slightly affected. Under cultivation condition of 30 degrees C, 170 r/min, 1% inoculation (D600 = 0.4), the accumulation of phosphorus was various by strains and cultivation concentration of phosphorus as well: In 2 mg/L phosphorus concentration medium, the highest phosphorus-accumulation ratio of strains Y11 and Y4-2 were 96.13% and 94.65%, the phosphorus concentration decreased from 2 mg/L to 0.08 mg/L and 0.11 mg/L, respectively. In 5 mg/L phosphorus concentration medium, the highest phosphorus-accumulation ratio of strains Y11 and Y4-2 were 95.94% and 71.19%, the phosphorus concentration decreased from 5 mg/L to 0.20 mg/L and 1.44 mg/L, respectively. In 8 mg/L phosphorus concentration medium, the highest phosphorus-accumulation ratio of strains Y11 and Y4-2 were 71.24% and 47.81%, the phosphorus concentration decreased from 8 mg/L to 2.30 mg/L and 4.18 mg/L, respectively. For the P removal of Yunnan Dianchi water sample containing 1.01 mg/L phosphorus, Y11 and Y4-2 were successful to decrease the phosphorus concentration from 1.01 mg/L to 0.06 mg/L in 6 h and 48 h, respectively. The results indicated that Acinetobacter sp.Y11 and Y4-2 possess high ability of phosphorus removal and suitability to various water environments. Y11 strain adapt to all kinds of eutrophic waterbody even polluted with phenanthrene, Y4-2 adapt to pH < or = 8.0 eutrophic waterbody with phenanthrene pollution.

[Study on transformation of P-dissolving Penicillium oxalicum P8 with double-marker vector expressing green fluorescent protein and hygromycin B resistance].

P-dissolving Penicillium oxalicum P8 was isolated previously in this lab which has a considerable ability to dissolve many kinds of inorganic phosphorus and improve crop growth. In order to study rhizosphere colonization of plants by Penicillium oxalicum P8, protoplasts were transformed with a double-marker expression vector of green fluorescent protein and hygromycin B resistance. Some transformants were selected which expressed both the GFP and hygromycin B phosphotransferase and did not show significant morphological or physiological differences as compared to wild-type strain. Southern blot analysis confirmed the heterogeneous genomic integration of the vector DNA into the transformants.