The presently reported study investigated seasonal fluctuations in the prevalence in four species of Nerocila infesting commercially exploited marine fishes representing the families Engraulidae, Clupeidae and Ambassidae, from the Malabar coast (Kerala, India). Seven of 56 fish species belonging to 23 families were infested by either one or two species of Nerocila. All the collected Nerocila species showed significant seasonal fluctuations in the prevalence of infestation, reaching maximum from October through April and minimum (or total absence of the parasites) from May through September. Such fluctuations were analyzed based on environmental parameters. Body surface, postero-ventral side of the head and the lateral line of the host fish form the major infestation site for the recovered Nerocila species. Skin lesion and hemorrhages were observed on the fish parasitized with these cymothoids.

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Background: Cymothoa frontalis Milne Edward, 1840 is a very poorly described cymothoid, notwithstanding the previous redescription of the female. Pertinently, to date, the host of C. frontalis has not been identified with adequate precision. Most of the descriptions of cymothoids carried out hitherto were based primarily on females, but practically ignoring other life cycle stages. The present paper redescribes the female and describes other life cycle stages of the species C. frontalis to get better precision in their identification. Results:The female phase of C. frontalis is redescribed according to type specimens extant in the NMNH, Paris, and also by the data obtained from live specimens collected during the present study. The general morphology and appendages of various life cycle stages of the species are described. Among 80 fish species from 35 families examined, C. frontalis was recovered only from Strongylura strongylura signifying its oligoxenous host specificity, the prevalence and intensity being 68.65% and 1.9, respectively. Each host fish in more than 85% of the population was infested with a pair of C. frontalis, in three combinations, predominantly with male-female pair (70.9%). C. frontalis exhibited strict site specificity attaching to the buccal cavity of the host fish. The study has also identified three major phases (marsupial, free living and infective) in the life cycle of C. frontalis. The zygotic-staged marsupiumites were developed through five sequential ontogenetic stages. The manca released from the marsupium become infective after a brief period of free swimming life. During the infective phase, C. frontalis completes remaining life cycle stages with successive moulting. Further, six successive stages of the ovigerous females have also been identified. Conclusions: The present redescription of the female and the description of transitional, male, juvenile and larvae of C. frontalis facilitate precise identification of the species at any stage of the life cycle. Further, the strict host and site specificities of the parasite, as borne out from the present study, and its high degree of prevalence in the host make C. frontalis as an ideal model organism to study the strategies to be adopted for the management of parasites infesting edible fishes.

Plackett±Burman design was used to ef®ciently select important media components in¯uencing lactic acid production in a two step screening procedure. A total of 36 screening experiments were conducted for studying the effect of various media components such as carbon and nitrogen (simple and complex) sources, minerals/buffering agents and a speci®c inducer for the production of lactic acid by Lactobacillus plantarum NCIM 2084. The eleven ingredients chosen after the ®rst screening experiments were further screened by a Plackett-Burman design consisting of 12 experiments. Lique®ed starch, wheat bran extract, ammonium nitrate, manganese sulphate and sodium acetate were chosen as promising ingredients for further optimisation studies. The highest yield of 41.9 g/l of lactic acid was obtained at the end of 24 hours of fermentation which corresponded to 90% conversion, on the basis of sugar supplied. IntroductionLactic acid ®nds application in food industry, as an additive to soft drinks and essences, in pharmaceuticals, leather and plastic industries. The fermentation route, is gaining importance in recent years in the context of rising cost of petrochemicals, and the availability of improved and better methods of fermentation. Work on the development of an ef®cient and economical process for lactic acid in our laboratory involved the optimisation of the nutritional parameters of the fermentation medium. This required the screening and selection of the media components including carbon, and nitrogen sources, minerals and trace elements etc.Screening of various nutrients by conventional single dimensional search, involves changing one independent variable, at a time while ®xing the others at a constant level which is time consuming and cumbersome. Statistical approach for the optimisation of media effectively tackles the problem which involves speci®c design of experiments which minimises the error in determining the effect of parameters and the results are achieved in an economical manner.Plackett±Burman saturated orthogonal designs [1] work at two levels, and can be constructed on the basis of fractional replication of a full factorial design. This design allows reliable short listing of a small number of ingredients for further optimisation and allows one to obtain, unbiased estimates of linear effects of all the factors with maximum accuracy for a given number of observations, the accuracy being the same for all effects [2].A number of reports are available on the effect of various carbon and nitrogen sources on lactic acid production. Molasses, whey, corn starch are some of the commonly used carbon sources while malt sprouts, malt extract, yeast extract, corn steep liquor are the nitrogenous sources used for lactic acid production. Media optimisation for lactic acid production has generally been carried out by the conventional single factor approach which is time consuming and cumbersome. The use of Plackett±Burman design for screening a large number of carbon and nitrogen sources, minerals, inducers etc, for lact...