Degradation of nitrocellulose film under aerobic conditions by a newly isolated Rhodococcus pyridinivorans strain

The explosive and biorefractory nature of nitrocellulose (NC) poses major risks to both humans and the environment. Expanding the range of microorganisms capable of degrading NC is essential, though the most effective known microorganisms, Desulfovibrio genera and Fusarium solani, achieve degradation rates of 5%-25%. Here, a novel strain, Rhodococcus pyridinivorans LZ1 was isolated, demonstrating the ability to degrade NC, with its growth potentially enhanced by the presence of NC. The degradation process was monitored by assessing changes in nitrate, nitrite, and ammonium. Notably, the -OH strength of NC increased over time, whereas the energetic functional groups (-NO2 and O-NO2) diminished. Furthermore, the presence of NC enhanced nitrate esterase activity 1-2-fold, indicating that ammonification was the primary pathway for NC biodegradation. By converting the nitrate ester of NC into hydroxyl, R. pyridinivorans LZ1 mitigates the harmful effects of NC, offering a promising approach for the treatment of NC waste and wastewater.

Microorganisms for the oxidation of nitrated cellulose in its effluents (review)

The processes of microbiological destruction of toxic and large-tonnage waste are the most attractive processes for protecting the environment. The review considers the results of studies of microbial decomposition of nitrate esters, including hardly decomposable nitrocellulose. The published data show that specific microorganisms are able to degrade nitrated cellulose compounds under both anaerobic and aerobic conditions. The most promising microorganisms in terms of the efficiency of the nitrocellulose degradation process are bacteria belonging to Desulfovibrio genera, fungi Fusarium solani and Sclerotium rolfsii, as well as their co-cultivation. Recently, the first information about the enzymes involved in the process of nitrocellulose degradation, possible mechanisms of reactions carried out by these enzymes, and the effect of electron donors and acceptors adding to the process have been obtained. Contamination of industrial wastewater with nitrocellulose leads to treatment necessity by using cost-effective, harmless methods. A combined aerobic-anaerobic system, including both bacteria and fungi, has shown hopeful results.

Morphological growth pattern of Phanerochaete chrysosporium cultivated on different Miscanthus x giganteus biomass fractions

BACKGROUND

Solid-state fermentation is a fungal culture technique used to produce compounds and products of industrial interest. The growth behaviour of filamentous fungi on solid media is challenging to study due to the intermixity of the substrate and the growing organism. Several strategies are available to measure indirectly the fungal biomass during the fermentation such as following the biochemical production of mycelium-specific components or microscopic observation. The microscopic observation of the development of the mycelium, on lignocellulosic substrate, has not been reported. In this study, we set up an experimental protocol based on microscopy and image processing through which we investigated the growth pattern of Phanerochaete chrysosporium on different Miscanthus x giganteus biomass fractions.

RESULTS

Object coalescence, the occupied surface area, and radial expansion of the colony were measured in time. The substrate was sterilized by autoclaving, which could be considered a type of pre-treatment. The fastest growth rate was measured on the unfractionated biomass, followed by the soluble fraction of the biomass, then the residual solid fractions. The growth rate on the different fractions of the substrate was additive, suggesting that both the solid and soluble fractions were used by the fungus. Based on the FTIR analysis, there were differences in composition between the solid and soluble fractions of the substrate, but the main components for growth were always present. We propose using this novel method for measuring the very initial fungal growth by following the variation of the number of objects over time. Once growth is established, the growth can be followed by measurement of the occupied surface by the mycelium.

CONCLUSION

Our data showed that the growth was affected from the very beginning by the nature of the substrate. The most extensive colonization of the surface was observed with the unfractionated substrate containing both soluble and solid components. The methodology was practical and may be applied to investigate the growth of other fungi, including the influence of environmental parameters on the fungal growth.