The aim of this study was to investigate the antimicrobial property of the compounds present in the lichen Usnea albopunctata. Ethyl acetate extract of the lichen was purified by column chromatography to yield a major compound which was characterised by spectroscopic methods as protocetraric acid. In this study, protocetraric acid recorded significant broad spectrum antimicrobial property against medically important human pathogenic microbes. The prominent antibacterial activity was recorded against Salmonella typhi (0.5 μg/mL). Significant antifungal activity was recorded against Trichophyton rubrum (1 μg/mL), which is significantly better that the standard antifungal agent. Protocetraric acid is reported here for the first time from U. albopunctata. Thus the results of this study suggest that protocetraric acid has significant antimicrobial activities and has a strong potential to be developed as an antimicrobial drug against pathogenic microbes.

The mealy bug, Rhizoecus amorphophalli, is a menace to the aroid farmers due to the intensive infestation on stored tubers. Spraying of pesticides was able to control this pest but it always left a chance for fungal growth. Bacterial endosymbionts associated with the insects provide several benefits to their host. Since such endosymbionts play a vital role even in the physiology of their host, revealing the types of bacteria associated with mealy bug will give basic information, which may throw light on the management of this noxious pest. The present study is the first to identify bacterial endosymbionts associated with R. amorphophalli employing phenotypic characterization and 16S rDNA sequencing. Three culturable bacteria, namely, Bacillus subtilis, Staphylococcus gallinarum, and Staphylococcus saprophyticus, were isolated from R. amorphophalli. Moreover, the antibiotic susceptibility tests against the isolated bacteria showed that all the isolates were susceptible to the three antibiotics tested, except cephalexin. Recently, endosymbionts are used as effective biocontrol agents (BCAs) and the present study will stand as a connecting link in identification and effective utilization of these endosymbionts as BCAs for management of R. amorphophalli.

Skin and chronic wound infections caused by various pathogenic bacteria are an increasing and urgent health problem worldwide. In the present investigation ethyl acetate extract of an Achromobacter sp. associated with a Rhabditis entomopathogenic nematode (EPN), displayed promising antibacterial property and was further purified by silica gel column chromatography to get three different cyclic dipeptides (CDPs). Based on the spectral data and Marfey's analyses, the CDPs were identified as cyclo(D-Leu-D-Arg) (1), cyclo(L-Trp-L-Arg) (2), and cyclo(D-Trp-D-Arg) (3), respectively. Three CDPs were active against all the 10 wound associated bacteria tested. The significant antibacterial activity was recorded by CDP 3, and highest activity of 0.5 μg/ml was recorded against Staphylococcus aureus and Pseudomonas aeruginosa. The synergistic antibacterial activities of CDPs and ampicillin were assessed using the checkerboard microdilution method. The results of the current study recorded that the combined effects of CDPs and ampicillin principally recorded synergistic activity. Interestingly, the combination of CDPs and ampicillin also recorded enhanced inhibition of biofilm formation by bacteria. Moreover, CDPs significantly stimulate the production of IL-10 and IL-4 (anti-inflammatory cytokines) by human peripheral blood mononuclear cells. CDPs do not make any significant effect on the production of pro-inflammatory cytokines like TNF-α. The three CDPs have been studied for their effect on intracellular S. aureus in murine macrophages (J774) using 24 h exposure to 0.5X, 1X, and 2X MIC concentrations. Significant decrease in intracellular S. aureus burden was recorded by CDPs. CDPs also recorded no cytotoxicity toward FS normal fibroblast, VERO, and L231 normal lung epithelial cell lines. Antimicrobial activity of the arginine containing CDPs against the wound associated bacteria is reported here for the first. Moreover, this is also the first report on the production of CDPs by Achromobacter sp. Finally, we conclude that the Achromobacter sp. is an incredibly promising source of natural bioactive secondary metabolites especially against wound pathogenic bacteria that may receive significant benefit in the field of human medicine in near future as topical agents.

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The present study was carried out to trace the life cycle of mealy bug, Rhizoecus amorphophalli on three different hosts including elephant foot yam, taro and tannia tubers. Investigation revealed that the mealy bug reproduces sexually and the adult female secretes an egg sac of white waxy substance in which eggs were laid. Female nymph moult normally, but male instar produces a cottony puparium around its body and form a pupal stage from which adult males emerge. On tubers of elephant foot yam, average fecundity and incubation period were 68.30±6.22 and 7.80±0.88 days respectively. But, it was significantly lesser for those on the taro and tannia tubers. Nevertheless irrespective of hosts, the percentage of hatching maintained uniformity. The total life cycle of bug which includes three instars and a pupal stage took 27.10 days for females and 22.40 days for males on tubers of elephant foot yam. The larval stages of mealy bug did not show prominent morphometric changes among the hosts used for life cycle study.