SYNERGISTIC AND INHIBITORY EFFECTS OF SEPTICEMIA BACTERIA ON SILKWORM

Ashok kumar H. K, Ramakrishna S, Rizwan Sharief and Rakesh Hand Girishkakade A. S. Department of Zoology, Bangalore University, Bangalore-560 056, India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Microbes spend energy to produce secondary metabolites (defensins) in order to colonize various environments. Production of defensins by septicemia causing bacteria of silkworm and its of synergistic or inhibitoryactivity on selected bacteria were studied. Well diffusion method was employed to define the defensins activity in microenvironment. Different aliquots of supernatant containing defensins fromSerratia sp., and Bacillus sp., were examined on test cultures of Escherichia coli and Staphylococcus aureus. Results revealed inhibition of E. coli and S. aureus by supernatants of Serratia species in different degree based on different concentrations. Therapeutic applications of defensins may potentially serve as an alternate to classical drug therapy for infections of humans by their specific and narrow spectrum of activity.

Introduction:-
The increasing concern of multi drug resistance (Goncalves et al., 2007) in bacterial species compelsto combat sustainable resistance by a novel method. In absolving drug resistance and treatment of sensitive strain causing diseases using bacteriocinshence becomes expedient.
Bacteria produces an extraordinary array of compounds viz., antibiotics, lytic agents, protein exotoxins, and bacteriocins for their defense. SepticemicDisease causing silkworm bacteria (Serratiamarcescens, Serratiaplymuthica and Bacillus cereus) with secondary metabolites producing ability are considered to be of paramount importance ( The production of bacteriocins from different bacterial species needs to be further investigated through Immunization of silkworm (Hara &Yamakawa, 1995) or by genetic engineering techniques. The production of these remarkable productscansolve drug resistance epidemic. Selective nutritional supplements in culturing of septicemic bacteria augmentbacteriocinsproduction in an industrial scale.

ISSN: 2320-5407
Int. J. Adv. Res. 6(9), 485-488 486 Methodology:-Well diffusion method Serratia and Bacillus sp., inherently produces a wide variety of distinguished pharmacologically active compounds, their activity can be analyzedby well diffusion method. Supernatants of silkworm septicemia causing bacteria (Serratia sp. and Bacillus sp.) were cultured in optimal nutrient broth at 30°C for 48h. Supernatants of Serratia sp., and Bacillus sp., were obtained by centrifugation at 6000 rpm. Gram-negative and Gram positive test bacteria Escherichia coli and Staphylococcus aureuswere cultured by pour plate method on Nutrient Agar medium to obtain lawns. Wells were made on bacterial lawns using cork borer to add supernatants in aliquots of 50 µl, 100 µl, 150 µl, and 200 µl and incubated at 37°C for 24hrs. (Wiegand et al., 2008).

Isolates producing secondary metabolites were employed on test bacteria to be assessed by well diffusion method
The standardization and application of varied concentrations were identified by the Well diffusion method. The secondary metabolite produced in septicemicS. marcescens, S. plymuthica and B. cereuswere recognized and varied inhibition concentration was evaluated using above method. The antagonistic effects of septicemia causing bacteria species were assessed by dispensing 50µl, 100µl, 150µl, and 200µl into wells.
B. cereus filtrate on examination against test bacteria S. aureusand E. coli lawns, the diameter of inhibition zone formed including well was found to be low in comparison to other examined bacteria. The S. marcescens inhibition zones increased in steady state with an increase in aliquots of supernatants on lawns of S. aureus, however on E. coli inhibition zones were comparatively low. S. plymuthicaon lawns of S. aureus showed high inhibition zone while with E. coli exhibited low inhibition zones even with increase in concentrations of filtrate aliquots. Bacilluscereus showed meager inhibition diameters for both S. aureus and E. coli. The summary of well diffusion results are summarized in Table1. 5.5 ± 0.5 5.8 ± 0.5 6.5 ± 0.5 6.8 ± 0.5 mm = mili meter, µl= microleter, Values are means (±SD), n=3 for each condition