The isolation and functional identification on producing cellulase of Pseudomonas mendocina

Elucidating biofilm diversity on water lily leaves through 16S rRNA amplicon analysis: Comparison of four DNA extraction kits

PREMISE

Within a broader study on leaf fossilization in freshwater environments, a long-term study on the development and microbiome composition of biofilms on the foliage of aquatic plants has been initiated to understand how microbes and biofilms contribute to leaf decay and preservation. Here, water lily leaves are employed as a study model to investigate the relationship between bacterial microbiomes, biodegradation, and fossilization. We compare four DNA extraction kits to reduce biases in interpretation and to identify the most suitable kit for the extraction of DNA from bacteria associated with biofilms on decaying water lily leaves for 16S rRNA amplicon analysis.

METHODS

We extracted surface-associated DNA from Nymphaea leaves in early stages of decay at two water depth levels using four commercially available kits to identify the most suitable protocol for bacterial extraction, applying a mock microbial community standard to enable a reliable comparison of the kits.

RESULTS

Kit 4, the FastDNA Spin Kit for Soil, resulted in high DNA concentrations with better quality and yielded the most accurate depiction of the mock community. Comparison of the leaves at two water depths showed no significant differences in community composition.

DISCUSSION

The success of Kit 4 may be attributed to its use of bead beating with a homogenizer, which was more efficient in the lysis of Gram-positive bacteria than the manual vortexing protocols used by the other kits. Our results show that microbial composition on leaves during early decay remains comparable and may change only in later stages of decomposition.

Bacterial cellulase from the intestinal tract of the sugarcane borer

Cellulolytic enzymes have wide use in several industrial segments (e.g. biofuels, pulp and paper, food, and cosmetics). However, one of the challenges is their large-scale production with high specific activity to eliminate the dependence of the purchase of enzymatic cocktails produced by commercial parties. The aims of this study were (1) isolation, selection, and partial characterization of bacterial cellulases present in the intestinal tract of the sugarcane borer and (2) to identify cellulase-producing bacteria by analyzing the 16S rDNA gene. Cellulase production and purification assays resulted in similar electrophoretic profiles between four bacterial strains. These strains were identified as Klebsiella pneumoniae, Klebsiella sp., and Bacillus sp. K. pneumoniae was the main cellulase-producing microorganism. Our results show the possibility of finding cellulolytic microorganisms that inhabit the gut of herbivorous animals, especially those that are predators of important crops of economic value. Furthermore, K. pneumoniae cellulase is of medical importance. In hospitals, health professionals, hospital technicians, patients and visitors wear clothes containing cellulose. Thus, K. pneumoniae within hospitals can contaminate these clothes and be spread to the environment. In that case, it would be important for the hospital's chemical sterilization products to have at least one cellulase inhibitor.

Improving the properties of straw biomass rattan by corn starch

As a kind of renewable resource and natural biomass, starch has been widely used to substitute plastics in the modern industry and is regarded as one of the most promising biodegradable materials. The newly developmental rattan, straw biomass rattan (SBR) as weaving material, has been exploited as per our previous work, which possessed advantages of both natural rattan and pure plastic rattan. The main objective of the work was to improve the properties of SBR by corn starch (CS). Based on the manufacturing of the above composites, the experiments of SBR that enhanced with CS on mechanical properties, melting performance, hydroscopicity, thermogravimetric analysis, and microstructures were tested in this study. The results revealed that when the content of CS increased gradually within the range of 0, 3, 6, 9 12, and 15 wt.%, the mechanical properties and melt index of the composite both increased first and then decreased, with 6 to 12 wt.% as the optimal dosage range. In contrast, the water absorption of SBR kept increased in this range, indicating an easier biodegradable. With CS added, the microstructure of SBR was examined by scanning electron microscope and found the microscopic surfaces and sections to become smoother, and that could improve the compatibility and tenacity between the materials. As a result, CS in moderation can be used as a supplement to enhance SBR, and improve their characteristics which will enhance the mechanical properties of the composites for future perspectives.