Optimizing Bioremediation: Elucidating Copper Accumulation Mechanisms of Acinetobacter sp. IrC2 Isolated From an Industrial Waste Treatment Center

Acinetobacter sp. IrC2 is a copper-resistant bacterium isolated from an industrial waste treatment center in Rungkut, Surabaya. Copper-resistant bacteria are known to accumulate copper inside the cells as a mechanism to adapt to a copper-contaminated environment. Periplasmic and membrane proteins CopA and CopB have been known to incorporate copper as a mechanism of copper resistance. In the present study, protein profile changes in Acinetobacter sp. IrC2 following exposure to copper stress were analyzed to elucidate the copper resistance mechanism. Bacteria were grown in a Luria Bertani agar medium with and without CuSO4 supplementation. Intracellular copper ion accumulation was quantified using atomic absorption spectrophotometry. Changes in protein profile were assessed using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The results showed that 6 mM CuSO4 was toxic for Acinetobacter sp. IrC2, and as a response to this copper-stress condition, the lag phase was prolonged to 18 h. It was also found that the bacteria accumulated copper to a level of 508.01 mg/g of cells’ dry weight, marked by a change in colony color to green. The protein profile under copper stress was altered as evidenced by the appearance of five specific protein bands with molecular weights of 68.0, 60.5, 38.5, 24.0, and 20.5 kDa, suggesting the presence of CopA, multicopper oxidase (MCO), CopB, universal stress protein (Usp), and superoxide dismutase (SOD) and/or DNA-binding protein from starved cells, respectively. We proposed that the mechanism of bacterial resistance to copper involves CopA and CopB membrane proteins in binding Cu ions in the periplasm and excreting excess Cu ions as well as involving enzymes that play a role in the detoxification process, namely, SOD, MCO, and Usp to avoid cell damage under copper stress.

Nanoflakes of chloride zinc–iron–aluminum-based layered double hydroxides obtained from industrial waste: a green approach to mass-scale production

A greener technology aiming at a smarter industrial waste treatment is proposed to produce chloride iron–zinc–aluminum layered double hydroxides (LDHs).

The Detrimental Effects of Punishment and Reward on Cooperation in the Industrial Waste Illegal Dumping Game

Background. Many studies have shown that sanctions promote cooperation in social dilemma situations. However, it has also been suggested that sanctions have a negative effect. The interactions among people and systems need to be considered to examine the consequences of sanctions. Aim. We examined whether rewards and mutual punishment increased non-cooperation. We regarded illegal industrial waste dumping as a social dilemma in which everyone bears the burden of the cost of illegal dumping, legal treatment is cooperative behavior, and illegal dumping is non-cooperative behavior. Method. We used the Industrial Waste Illegal Dumping Game. This game simulates the structure of industrial waste treatment (incomplete surveillance, various industries with different roles and payoffs, cost of cooperation, etc.) in addition to the social dilemma structure. Players take on roles in industrial waste treatment, negotiating and dealing with other players, and treating industrial waste. We set three conditions. In the reward condition, players can earn rewards by rapidly treating industrial waste. In the mutual punishment condition, players can mutually monitor and punish each other. In the control condition, neither reward nor punishment exists. Results. Non-cooperation occurred more frequently in the reward condition than in the control condition. Conversely, there was no difference in non-cooperation between the mutual punishment and control conditions. Players under the reward condition did not gather information proactively, and information on benefits was not shared. Conclusion. This study showed that sanctions caused non-cooperation. Social dynamics should be considered when evaluating the effectiveness of sanctions. Gaming allows us to examine social consequences, including social dynamics, which leads to discoveries not possible through traditional methods.