| Congresso Brasileiro de Microbiologia 2023 | Resumo: 111-1 | ||||
Resumo:Antibiotic resistance is a life-threatening challenge in modern medicine, resulting from the overuse and misuse of antibiotics. Developing new antibiotics is slow and expensive, necessitating alternative strategies to combat bacterial infections. Biotransformation using fungi, such as Aspergillus niger, can modify known molecules like lapachol, a natural naphthoquinone, to produce new compounds with enhanced properties. This study aimed to evaluate the antibacterial activity of biotransformed lapachol by A. niger against Gram-positive and Gram-negative bacteria. The A. niger LM5826 strain was obtained from the Collection of Microorganisms of Medical Interest – INPA, and lapachol and Imipenem were acquired from Sigma-Aldrich. A. niger LM5826 was incubated in PDA medium at 28°C for 7 days. Inoculum preparation involved adding 1x104 cells/mL of A. niger to 50 mL of Czapeck broth in Erlenmeyer flasks. The experiment comprised four variants: simultaneous inoculation of fungus and lapachol (50 μg/mL), fungus growth followed by lapachol addition, only fungus with medium, and only lapachol with medium. All variants were incubated at 28°C with constant agitation for 7 days, then separated from the mycelium using a paper filter. The broths were extracted three times with ethyl acetate (v/v) and concentrated using a rotary evaporator. Antibacterial activity was assessed using the well-diffusion method following the Clinical and Laboratory Standard Institute protocol (M02). Inoculum of Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 was prepared and spread on petri dishes containing Mueller Hinton medium. Wells (5mm diameter) were created using a sterilized pipette tip, and 200 μl of each extract (1mg/mL) was added, along with a negative control (10% dimethyl sulfoxide) and a positive control (Imipenem). After incubation at 28°C for 18 hours, the inhibition zones were measured using a digital caliper. Imipenem exhibited 45 mm inhibition zones against S. aureus, while E. coli showed resistance with no inhibition zone. Lapachol displayed inhibition zones of 39 mm and 13 mm against S. aureus and E. coli, respectively. All three extracts showed similar inhibition zones of 14 mm against E. coli. For S. aureus, the variant with simultaneous incubation of fungus and lapachol demonstrated the largest inhibition zone (32–38 mm), close to the positive control. Aspergillus has demonstrated the ability to biodegrade lapachol into two known secondary metabolites with antimicrobial activity. Ethyl acetate extracts of A. niger exhibited good antibacterial activity against S. aureus, supporting our findings. Biotransformation processes offer a simple and effective approach to overcoming antibiotic resistance. Further studies are necessary to better understand the biochemical processes involved in the formation of antibacterial metabolites. Given the increasing prevalence of multidrug-resistant organisms, the search for new molecules with antibacterial activity is crucial. Palavras-chave: Antibacterial activity, Biotransformation, Naphthoquinone Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |||||