-The rot disease of Laminaria occurs often in nurseries of sporeling and commercial cultivation in the sea and results in economic loss greatly. Usually the disease outbreaks accompanied with massive multiplication of...-The rot disease of Laminaria occurs often in nurseries of sporeling and commercial cultivation in the sea and results in economic loss greatly. Usually the disease outbreaks accompanied with massive multiplication of alginic acid decomposing bacteria. From the section of the decaying Lamuutria which resulted from the inoculation of alginic acid decomposing bacteria, it was observed that the bacteria invaded the epiderm of the Laminaria surface at first, then entered the ex-odermis, endodermis and pith. In addition, there were a great amount of bacteria in the intercellular region and a lot of free cells of the algae in the decaying areas. The wall of some free cells was decomposed, which led to soft tissue or disintegration. Alginic acid decomposing bacteria are normal epiphytic microorganisms growing on Lamuutria surface. These bacteria do not cause disease at normal environmental conditions. The experiments showed that the unfavourable conditions, e. g. , wounding, overcrowding, high temperature reduced the ability of antibacterial activity and made the algae more susceptible to the pathogens and favoured the multiplication of alginic acid decomposing bacteria and finally led to the disease outbreak. The unfavourable environmental factors which resulted from a variety of reasons were the main cause of the disease.展开更多
In this study,we determined pH,phosphorus content and the number of P-dis-solving/decomposing bacteria in relation to the depth in the sediment of Guanting reservoir in Beijing.The pH value was slightly increased from...In this study,we determined pH,phosphorus content and the number of P-dis-solving/decomposing bacteria in relation to the depth in the sediment of Guanting reservoir in Beijing.The pH value was slightly increased from 8.0 in the surface to 8.5 in the bottle(69 cm in depth)of sediment.The highest P content,1269 mg/kg,was detected in the 35 cm layer,followed by the 5 cm(993 mg/kg)and 69 cm(580 mg/kg)layers.The number of inorganic P-dissolving bacteria varied from 6(102 to 8(104 and the organic P-discomposing bacteria were from 1.9(103 to 6.3(104 per gram sediment in different depths,which were counted under 28℃and 20℃(pH7.5 and 8.5.The number of P-dissolving/discomposing bacteria was directly correlated to the P content in each layer of sediments.The analysis of P-dissolving/decomposing ability of bacteria showed that some of these bacteria were also capable of accumulating P intracellularly.The intracellular P-accumulation was more efficient at lower temperature;in contrast,the activity of P-dissolving/decomposing was stronger at higher temperature.So the content of dissolved P in water body,or quality of water,could be affected by the change of temperature via the regulation of bacterial activity.On the basis of 16S rDNA sequencing,the 13 efficient P-dis-solving/decomposing bacteria were identified as Bacillus spp.,Bacterium sp.,Microbacterium sp.,Paenibacillus sp.and Pseudomonas sp.展开更多
The upper and lower portions of Musa sapientum pseudo-stem sheaths were exposed in four types of treatments： pectin decomposing bacteria, magnesium oxide （MgO）, both pectin decomposing bacteria and MgO and control....The upper and lower portions of Musa sapientum pseudo-stem sheaths were exposed in four types of treatments： pectin decomposing bacteria, magnesium oxide （MgO）, both pectin decomposing bacteria and MgO and control. The fibre strength properties were tested using SIRIM Standard methods and colour changed using gray scale. The bioaugmentation of pectin decomposing bacteria together with MgO additions were found to enhance retting process and reduced retting periods 52% and yielded better strength on the fibres. The lower portion pseudo-stem sheaths gave the higher strength than upper portion. Colour changed showed that the bioaugmentation of pectin bacteria enhanced the degradation colouring compound in banana fibres.展开更多
文摘-The rot disease of Laminaria occurs often in nurseries of sporeling and commercial cultivation in the sea and results in economic loss greatly. Usually the disease outbreaks accompanied with massive multiplication of alginic acid decomposing bacteria. From the section of the decaying Lamuutria which resulted from the inoculation of alginic acid decomposing bacteria, it was observed that the bacteria invaded the epiderm of the Laminaria surface at first, then entered the ex-odermis, endodermis and pith. In addition, there were a great amount of bacteria in the intercellular region and a lot of free cells of the algae in the decaying areas. The wall of some free cells was decomposed, which led to soft tissue or disintegration. Alginic acid decomposing bacteria are normal epiphytic microorganisms growing on Lamuutria surface. These bacteria do not cause disease at normal environmental conditions. The experiments showed that the unfavourable conditions, e. g. , wounding, overcrowding, high temperature reduced the ability of antibacterial activity and made the algae more susceptible to the pathogens and favoured the multiplication of alginic acid decomposing bacteria and finally led to the disease outbreak. The unfavourable environmental factors which resulted from a variety of reasons were the main cause of the disease.
基金surpported by the National Basic Research Program(Grant No.G1999045709).
文摘In this study,we determined pH,phosphorus content and the number of P-dis-solving/decomposing bacteria in relation to the depth in the sediment of Guanting reservoir in Beijing.The pH value was slightly increased from 8.0 in the surface to 8.5 in the bottle(69 cm in depth)of sediment.The highest P content,1269 mg/kg,was detected in the 35 cm layer,followed by the 5 cm(993 mg/kg)and 69 cm(580 mg/kg)layers.The number of inorganic P-dissolving bacteria varied from 6(102 to 8(104 and the organic P-discomposing bacteria were from 1.9(103 to 6.3(104 per gram sediment in different depths,which were counted under 28℃and 20℃(pH7.5 and 8.5.The number of P-dissolving/discomposing bacteria was directly correlated to the P content in each layer of sediments.The analysis of P-dissolving/decomposing ability of bacteria showed that some of these bacteria were also capable of accumulating P intracellularly.The intracellular P-accumulation was more efficient at lower temperature;in contrast,the activity of P-dissolving/decomposing was stronger at higher temperature.So the content of dissolved P in water body,or quality of water,could be affected by the change of temperature via the regulation of bacterial activity.On the basis of 16S rDNA sequencing,the 13 efficient P-dis-solving/decomposing bacteria were identified as Bacillus spp.,Bacterium sp.,Microbacterium sp.,Paenibacillus sp.and Pseudomonas sp.
文摘The upper and lower portions of Musa sapientum pseudo-stem sheaths were exposed in four types of treatments： pectin decomposing bacteria, magnesium oxide （MgO）, both pectin decomposing bacteria and MgO and control. The fibre strength properties were tested using SIRIM Standard methods and colour changed using gray scale. The bioaugmentation of pectin decomposing bacteria together with MgO additions were found to enhance retting process and reduced retting periods 52% and yielded better strength on the fibres. The lower portion pseudo-stem sheaths gave the higher strength than upper portion. Colour changed showed that the bioaugmentation of pectin bacteria enhanced the degradation colouring compound in banana fibres.
