The utilization of potato waste liquid instead of synthetic substrates for lactic acid production cannot only reduce the production cost but also makes the process environment effective. Unlike many lactic acid bacteria, lactic acid producing Rhizopus strains generates L(+) lactic acid as a sole isomer of lactic acid. Furthermore, some Rhizopus spp. are amylolytic in nature and can produce lactic acid from starchy substrates without prior saccharification. This study aimed at the utilization of potato waste liquid for the production of L(+) lactic acid using amylolytic Rhizopus oryzae MTCC 8784. The effect of media components and process parameters on simultaneous saccharification and fermentation of potato waste liquid by fungal strain has been studied to maximize the production of L(+) lactic acid. The results revealed that highest lactic acid production (15.5 g l–1) was obtained with potato waste liquid containing 30 g l–1 starch supplemented with soya okara hydrolysate (1.5%, v/v), calcium carbonate (1.5%, w/v), and salts. In terms of process parameters, the maximum L(+) lactic acid (18.15 g l–1) production was obtained at pH 6 with temperature 30 °C, agitation of 150 r.p.m., after incubation period of 48 h.
β-Galactosidase is an enzyme of commercial importance owing to its multiple benefits. Among all microbial sources, fungal species are of great interest for the production of this enzyme. Thus, the aim of this present work was to optimize the media as well as process parameters to achieve maximum β-Galactosidase production by solid state fermentation using the fungal isolate Rhizomucor pusillus. Various agro-industrial residues were tested for carbon as well as for nitrogen sources. The different process parameters were also studied to observe their effects on β-galactosidase production. Among all screened agro-industrial residues, wheat bran and corn steep liquor had the potential to be used as carbon and nitrogen sources, respectively; whereas MgSO4 was found to be a suitable salt supplement. The optimal process parameters included particle size of 1000 microns, 50% moisture content, pH 5.5, 50 ºC temperature, and 7 days of fermentation.
Lactic acid bacteria in fermented foods help in the improvement of flavour, preservation of the nutritive values of the raw material, and inhibition of growth or killing of food spoilage and pathogenic bacteria. Beside other metabolites, the produced bacteriocin, which is a ribosomally synthesized antimicrobial peptide, is the major metabolite involved in the killing of food spoilage microorganisms and acts as a biopreservative. In search of a bacteriocin having specific inhibitory activity against food pathogenic bacteria, isolation of bacteriocin producing lactic acid bacteria from various food items was carried out. Based on maximum production of the bacteriocin, strain BS13 was characterized and was further identified as Enterococcus faecium BS13 on the basis of physicochemical properties and 16S rRNA analysis. In MRS medium this isolate presented the maximum production of bacteriocin (27 306 AU ml−1) after 18 h of incubation period. BS13 bacteriocin showed antimicrobial activity against a wide range of bacteria, including Bacillus subtilis, Staphylococcus sp., Pediococcus sp., Listeria monocytogenes and Lactobacillus sp.