Degradation of nitrocellulose-based paint by Desulfovibrio desulfuricans ATCC 13541

Nitrocellulose is one of the most commonly used compounds in ammunition and paint industries and its recalcitrance to degradation has a negative impact on human health and the environment. In this study the capability of Desulfovibrio desulfuricans ATCC 13541 to degrade nitrocellulose as binder in paint was assayed for the first time. Nitrocellulose-based paint degradation was followed by monitoring the variation in nitrate, nitrite and ammonium content in the culture medium using Ultraviolet-Visible spectroscopy. At the same time cell counts and ATP assay were performed to estimate bacterial density and activity in all samples. Infrared spectroscopy and colorimetric measurements of paint samples were performed to assess chemical and colour changes due to the microbial action. Microscope observations of nitrocellulose-based paint samples demonstrated the capability of the bacterium to adhere to the paint surface and change the paint adhesive characteristics. Finally, preliminary studies of nitrocellulose degradation pathway were conducted by assaying nitrate- and nitrite reductases activity in D. desulfuricans grown in presence or in absence of paint. We found that D. desulfuricans ATCC 13541 is able to transform nitrocellulose as paint binder and we hypothesised ammonification as degradation pathway. The results suggest that D. desulfuricans ATCC 13541 is a good candidate as a nitrocellulose-degrading bacterium

Evaluation of three biocide strategies in planktonic Nostoc sp. PCC 9104 stone biofilm-forming cyanobacterium by quantification of the color variations

Cyanobacterial response to three biocide strategies: (i) a commercial isothiazoline biocide (Biotin T\uae), (ii) high temperature (37\ubaC) and (iii) UV-C germicidal irradiation on short term was studied with the aim of assessing the usefulness of CIELAB color parameters (L*, a*, b*, C*ab and h\ubaab) in monitoring the effectiveness of biocide treatments. The experimental setup consisted of several samples from the same culture, a pure planktonic culture of an aeroterrestrial stone biofilm-forming cyanobacterium of the genus Nostoc (PCC 9104), testing the three biocide strategies at the same time. CIELAB color data were supported by spectrophotometric measurements of chlorophyll a, phycobiliproteins and total carotenoids, as well as adenosine triphosphate (ATP) assay. Results suggested that some of the CIELAB parameters could be profitably used to monitor the effectiveness of biocide treatments