Biodegradation of Different Types of Plastics by Tenebrio molitor Insect.

Looking for new, sustainable ways to utilize plastics is still a very pertinent topic considering the amount of plastics produced in the world. One of the newest and intriguing possibility is the use of insects in biodegradation of plastics, which can be named entomoremediation. The aim of this work was to demonstrate the ability of the insect Tenebrio molitor to biodegrade different, real plastic waste. The types of plastic waste used were: remains of thermal building insulation polystyrene foam (PS), two types of polyurethane (kitchen sponge as PU1 and commercial thermal insulation foam as PU2), and polyethylene foam (PE), which has been used as packaging material. After 58 days, the efficiency of mass reduction for all of the investigated plastics was 46.5%, 41.0%, 53.2%, and 69.7% for PS, PU1, PU2, and PE, respectively (with a dose of 0.0052 g of each plastic per 1 mealworm larvae). Both larvae and imago were active plastic eaters. However, in order to shorten the duration of the experiment and increase the specific consumption rate, the two forms of the insect should not be combined together in one container.

A New Approach to Quantifying Bioaccumulation of Elements in Biological Processes.

Bioaccumulation, expressed as the bioaccumulation factor (BAF), is a phenomenon widely investigated in the natural environment and at laboratory scale. However, the BAF is more suitable for ecological studies, while in small-scale experiments it has limitations, which are discussed in this article. We propose a new indicator, the bioaccumulation index (BAI). The BAI takes into account the initial load of test elements, which are added to the experimental system together with the biomass of the organism. This offers the opportunity to explore the phenomena related to the bioaccumulation and, contrary to the BAF, can also reveal the dilution of element concentration in the organism. The BAF can overestimate bioaccumulation, and in an extremal situation, when the dilution of element concentration during organism growth occurs, the BAF may produce completely opposite results to the BAI. In one of the examples presented in this work (Tschirner and Simon, 2015), the concentration of phosphorous in fly larvae was lower after the experiment than in the younger larvae before the experiment. Because the phosphorous concentration in the feed was low, the BAF indicated a high bioaccumulation of this element (BAF = 14.85). In contrast, the BAI showed element dilution, which is a more realistic situation (BAI = -0.32). By taking more data into account, the BAI seems to be more valid in determining bioaccumulation, especially in the context of entomoremediation research.

Biochar addition reinforces microbial interspecies cooperation in methanation of sugar beet waste (pulp).

Biogas production and microbial community structure were analyzed as an effect of biochar addition to a fermentation sludge containing sugar beet pulp. Positive effects of the treatment including an increase in process efficiency and better biogas quality were noted. The effect of biochar on AD (anaerobic digestion process) microbial communities was investigated after total DNA extraction from biochar-amended fermentation mixtures by PCR amplification of bacterial 16S rRNA gene fragments and Illumina amplicon sequencing. A combination of microbiological and physico-chemical analyses was used to study the mechanism by which biochar influences the process of anaerobic digestion of sugar beep pulp. It was found that the main reason of the changes in biogas production was the reshaping of the microbial communities, in particular enrichment of Bacteroidales and Clostridiales. It was proposed that biochar, in addition to being a conductor for mediating interspecies electron transfer, serves also as a habitat for hydrolytic bacteria. It was elucidated that the main driving force for the preferential colonization of biochar surfaces is its hydrophobicity. The presented research indicates the high potential of biochar to stimulate the methane fermentation process.

Hermetia illucens exhibits bioaccumulative potential for 15 different elements - Implications for feed and food production.

A new branch of the insect-based food and feed industry is intensively developing all over the world, the best proof of which is the recent change in legislation at the European level allowing the use of insect protein in the production of feed for aquaculture animals. Previous publications have proven that some heavy metals can be bioaccumulated in fly H. illucens (black soldier fly), even when the insect is raised on optimal feed with an acceptable heavy metal content. The purpose of this study was to determine the bioaccumulation potential of H. illucens in relation to micro- and macroelements, toxic elements and for the first time, selected non-essential elements from optimal feed. Our results showed that bioaccumulation of Ba, Bi, Cu, Fe, Hg, Mg, Mo, Se and Zn occurred in all stages of insect development and in puparia, while bioaccumulation of Al, As, Co, K, Pb and Si was not found. The highest bioaccumulation factors were obtained for Ca and Mn in puparia - 38 and 21 respectively. In addition, Ca, Cd, Ga, Mn, P and S were bioaccumulated only in some developmental stages of the insect. The results are discussed in the context of the safety of feed and food production from H. illucens.