O objetivo do estudo foi avaliar comparativamente a atividade antibacteriana de seis plantas indianas contra linhagens clínicas de Streptococcus mutans, que foram isoladas das amostras de biofilme dental de 45 pacientes pediátricos, com 0,2% de clorexidina. Seis extratos vegetais foram preparados em três formas diferentes, a saber, extratos aquosos, extratos à base de solventes orgânicos e extratos brutos. Os testes de sensibilidade antimicrobiana foram realizados por método de difusão em agar. A atividade antimicrobiana dos extratos foi determinada através da medição da zona de inibição, em milímetros, produzida contra os isolados bacterianos. Os resultados mostraram que o extrato de alho cru apresentou maior atividade antibacteriana do que a clorexidina. O extrato aquoso de amla e o extrato à base de solventes orgânicos de gengibre mostraram a máxima atividade antibacteriana contra S. mutans, enquanto o extrato aquoso de tulsi (manjericão) e o extrato à base de solventes orgânicos de amla mostraram mínima atividades antibacteriana. Este estudo sugere que extratos de plantas como o alho em forma bruta, amla como infusão aquosa e gengibre como tintura alcoólica tem um potencial para o controle de S. mutans. Estes extratos podem ser utilizados como uma via alternativa para a prevenção de cáries dentárias ou sob a forma de bochechos, que são seguros e econômicos.

The aim of the study was to comparatively evaluate the antibacterial activity of six Indian plant extracts and 0.2% chlorhexidine against clinical strains of Streptococcus mutans, which were isolated from the plaque samples of 45 pediatric patients. Six plant extracts were prepared in three different forms, namely aqueous extracts, organic solvent-based extracts and crude (raw) extracts. The antimicrobial sensitivity testing was done by agar well diffusion method. Antimicrobial activity of the extracts was determined by measuring the mean zones of inhibition (mm) produced against the bacterial isolates. Results showed that crude garlic extract exhibited greater antibacterial activity than chlorhexidine. Aqueous extract of amla and organic solvent-based extract of ginger showed the maximum antibacterial activity against S. mutans, whereas aqueous extract of tulsi and organic solvent based extract of amla showed the minimum antibacterial activity. This study suggests that plant extracts like garlic in crude form, amla as aqueous infusion and ginger as alcoholic tincture have potential for the control of S. mutans. These extracts can be used as an alternative remedy for dental caries prevention or in the form of mouthwash, which is safe and economical.

Several naphthalene and anthracene degrading bacteria were isolated from rhizosphere of Populus deltoides, which were growing in non-contaminated soil. Among these, four isolates, i.e. Kurthia sp., Micrococcus varians, Deinococcus radiodurans and Bacillus circulans utilized chrysene, benzene, toluene and xylene, in addition to anthracene and naphthalene. Kurthia sp and B. circulans showed positive chemotactic response for naphthalene and anthracene. The mean growth rate constant (K) of isolates were found to increase with successive increase in substrate concentration (0.5 to 1.0 mg/50ml). B. circulans SBA12 and Kurthia SBA4 degraded 87.5% and 86.6% of anthracene while, Kurthia sp. SBA4, B. circulans SBA12, and M. varians SBA8 degraded 85.3 %, 95.8 % and 86.8 % of naphthalene respectively after 6 days of incubation as determined by HPLC analysis.