Chemical composition and antimicrobial activities of wood vinegars from carambola, coconut shells and mango against selected plant pathogenic microorganisms

Aims@#This work aimed to evaluate the antimicrobial activities of three different sources of wood vinegars obtained from pyrolysis of carambola (Averrhoa carambola), coconut shells (Cocos nucifera) and mango (Mangifera indica) and to identify their chemical composition. @*Methodology and results@#Agar well diffusion technique was employed to assay the antifungal activity of the wood vinegars against Fusarium oxysporum, Colletotrichum gleosporoides, and Pestalotiopsis microspora and disc diffusion technique for antibacterial screening against Ralstonia solanacearum. The chemical compositions of these wood vinegars were also analyzed using GC-MS by employing the headspace technique. All wood vinegars exhibited antimicrobial activity against tested pathogens. Wood vinegar from carambola exhibited the most promising antimicrobial effect followed by coconut shells and mango. The GC-MS analysis revealed the wood vinegars from coconut shells, carambola, and mango are different in the chemical composition and active compounds. Major compounds identified in coconut shells are furfural, phenol, benzofuran, acetic acid, hexanal, ethanone, and formic acid. In carambola, the main compounds are furfural, imidazole, 3-pyridinecarboxaldehyde, benzaldehyde, phenol, benzofuran, indene, acetic acid, indazole, naphthalene, cyclohexanecarboxylic acid, palmitamide, palmitic acid, heptadecanenitril, and sterylamide. Meanwhile, the main chemical compounds in the pruning of mango-based vinegar consist of toluene, furfural, imidazole, annulene, benzaldehyde, phenol, carbamic acid, acetic acid, naphthalene, heptadecanenitril, and stearylamide.@*Conclusion, significance and impact of study@#It is suggested that wood vinegar from carambola, coconut shells, and mango is a promising antimicrobial agent in plant disease control, showing good potential for inhibition of selected plant pathogenic microorganisms.

Identification and characterization of lactic acid bacteria isolated from fruit tree rhizosphere in MARDI, Malaysia

Aims: Lactic acid bacteria (LAB) have promising applications in the biotechnology industry. As their diversity in soil is largely unexplored, a study was undertaken to collect LAB from the soil, and to characterize the isolates. Methodology and results: Soil samples from around various fruit trees in MARDI were collected for LAB isolation by accumulation/incubation method. The isolates were examined for their morphological and biochemical characteristics, and their 16S rDNA sequences. Morphological and biochemical analysis showed that all isolates are gram positive with different characteristic for each isolates. Further identification were performed and soil samples was found to contain diverse genera and species of LAB, including Lactobacillus sp. and Bacillus sp. Selected isolates were tested for resistance against six antibiotics using agar dilution method. Widespread antibiotic resistance among the strains tested was found towards ampicillin, kanamycin, rifampicin and penicillin. Conclusion, significance and impact study: LAB have the ability in producing acid and antimicrobial compound which are useful in various industry. Fastidious characteristics of LAB are among the limitations and challenges in industrial applications. Diversity of lactic acid-producing bacteria was encountered in the soil which may be useful and have different characteristics from LAB isolates elsewhere.