Growth of Lactobacillus plantarum in media containing hydrolysates of fish viscera

A novel Lactiplantibacillus plantarum strain: probiotic properties and optimization of the growth conditions by response surface methodology

The objective of this study is to explore the probiotic properties and optimal growth conditions of Lactiplantibacillus plantarum BG24. L. plantarum BG24 exhibited a remarkable ability to utilize lactose, and to grow under acidic conditions and in the presence of high levels of bile salts. The strain showed the highest antibacterial activity against L. monocytogenes Scott A (zone of inhibition: 26 mm). L. plantarum BG24 was found to be resistant to 8 of the tested 19 antibiotics using the disc diffusion method.and its multiple antibiotic resistance (MAR) index was calculated as 0.421. The adhesion rate to human intestinal epithelial Caco-2 cells was determined as 37.51%. The enzyme profile of L. plantarum BG24 was investigated using API ZYM test kit and the highest enzymatic activities were found for Leucine arylamidase, β-glucosidase, Valine arylamidase, β-galactosidase and N-acetyl-β-glucosaminidase. L. plantarum BG24 strain showed higher microbial growth under static conditions (6.60 OD600) compared to 100 rpm (5.73 OD600) and 200 rpm (5.02 OD600) shaking speed due to its facultative anaerobic characteristic. However, different inoculation rates and glucose addition did not make a statistically significant difference on biomass formation (p > 0.05). The specific growth rate of L. plantarum BG24 was 0.416 h-1, the doubling time was 1.67 h, and the biomass productivity value was 0.14 gL-1 h-1 in the original MRS broth (pH 5.7) while higher values were found as 0.483 h-1, 1.43 h and 0.17 gL-1 h-1, respectively, in MRS broth (pH 6.5) medium enriched with 5 g/L yeast extract. The stirred tank bioreactor was used to optimise the growth of BG24 strain. The process variables was optimized at 0.05 vvm of aeration rate, 479 rpm of agitation speed, 3% of inoculation rate and 18 h of incubation time. The maximum biomass (g/L) production was obtained as 3.84 g/L at the optimized conditions.

Characterizing Selected Sorghum Grain Varieties and Evaluating the Suitability of Their Malt Extracts for Cultivating Microbial Biomass

Microbial biomass is cultivated for different technological applications including food processing, medicine, waste management, and research. The conventional growth media used are generally expensive thus necessitating the development of more affordable alternatives. In this study, four sorghum grain varieties, SESO 1, SESO 3, Epuripur, and Eyera, and their malt extracts were characterized which is aimed at determining their suitability for growing microbial biomass. The varieties had kernel length, kernel width, kernel thickness, and thousand kernel weigh equivalent to 3.8-4.3 mm, 3.2-4.5 mm, 2.4-2.8 mm, and 12.4-20.2 g, respectively. SESO 1 and Epuripur had corneous endosperm textures whereas those of SESO 3 and Eyera were intermediate and floury, respectively. Varieties had germinative energies > 90% and total defects < 8%. SESO 3 had the highest (p < 0.05) crude protein (10.8 ± 0.3%) and dietary fiber (22.5 ± 0.4%) whereas Epuripur had the highest (p < 0.05) starch (81.6 ± 0.0%) and crude fat (2.9 ± 0.1%). There was no significant difference (p > 0.05) in the ash contents (2.1 ± 0.0%). The total sugars, free amino nitrogen, condensed tannins, and pH of the malt extracts were 106-116 g/L, 70-78 mg/L, 0.1-0.6 mg/mL, and 5.5-5.7, respectively. The composition of the sorghum malt extracts suggests their potential for use in cultivating microbial biomass.

Carotenoids produced by the deep-sea bacterium Erythrobacter citreus LAMA 915: detection and proposal of their biosynthetic pathway

Technologies based on synthetic biology to produce bacterial natural carotenoids depend on information regarding their biosynthesis. Although the biosynthetic pathway of common carotenoids is known, there are carotenoids whose pathways are not completely described. This work aimed to mine the genome of the deep-sea bacterium Erythrobacter citreus LAMA 915, an uncommon bacterium that forms yellow colonies under cultivation. This work further explores the potential application of the carotenoids found and low-cost substrates for bacterial growth. A combined approach of genome mining and untargeted metabolomics analysis was applied. The carotenoid erythroxanthin sulfate was detected in E. citreus LAMA 915 cell extract. A proposal for carotenoid biosynthesis by this bacterium is provided, involving the genes crtBIYZWG. These are responsible for the biosynthesis of carotenoids from the zeaxanthin pathway and their 2,2'-hydroxylated derivatives. E. citreus LAMA 915 extracts showed antioxidant and sun protection effects. Based on the high content of proteases and lipases, it was possible to rationally select substrates for bacterial growth, with residual oil from fish processing the best low-cost substrate selected. This work advances in the understanding of carotenoid biosynthesis and provides a genetic basis that can be further explored as a biotechnological route for carotenoid production.

Sorghum Malt Extract as a Growth Medium for Lactic Acid Bacteria Cultures: A Case of Lactobacillus plantarum MNC 21

Cultivation of lactic acid bacteria cultures is vital for research and commercial production of fermented foods. However, the conventional growth media used are generally costly. Malt extracts from four sorghum varieties (SESO 1, SESO 3, Epuripur, and Eyera) were evaluated as alternative low-cost growth media for Lactobacillus plantarum MNC 21. Saccharified sorghum malt extracts were inoculated with 4 log cfu/mL MNC 21 and incubated at 30°C for 24 h. MRS broth was the reference medium. Microbial counts, pH, titratable acidity (TA), free amino nitrogen (FAN), and total sugars were measured. Maximum microbial counts in the extracts and MRS broth were 9 and 10 log cfu/mL, respectively. Maximum growth rate in the extracts was 0.7-0.9 log cfu/mL/h and 0.8 log cfu/mL/h in MRS broth. The final pH of the extracts was 3.5-3.6, with an overall increase in TA of 1.2% in Epuripur and 0.2% in other varieties. Final pH and TA of MRS broth were 4.1 and 1.3%, respectively. Total sugars dropped by 95.2% and FAN by 2.1% in MRS broth. In contrast, total sugars and FAN dropped by 5.6-9.1% and 24.9-32.7% respectively, in the extracts. Sorghum malt extracts can be adopted as alternative low-cost growth media for lactic acid bacteria cultures.

Using Various Approaches of Design of Experiments for High Cell Density Production of the Functionally Probiotic Lactobacillus plantarum Strain RPR42 in a Cane Molasses-based Medium

Considering the economic importance of the probiotics, industrial production of their biomass became important. Cane molasses, as an industrial byproduct, was used in this study to design a medium for biomass overproduction of a functionally probiotic strain, designated as Lactobacillus plantarum strain RPR42. The results showed that strain RPR42 can be best grown anaerobically in 22.5% cane molasses solution. Also, the findings of the single variable at a time experiments and either factorial design indicated that the optimal growth of strain RPR42 can be observed when beef extract, casein hydrolysate, and yeast extract were added into the medium. The central composite design experiments suggested a medium which was designated as cane molasses medium (CMM). Eventually, this medium contained 21.9% cane molasses, 30.72 g/L of a combined mixture of nitrogenous compounds: 0.0754% of a 1:1:1 mixture of polysorbates 20, 60, and 80, and 18.53 gr/L of the combined minerals. Such an optimized cane molasses-based medium supported a significant biomass production since a considerably high cell density, 13.8 g/L/24 h of dry biomass, of the strain was produced. Hence, cane molasses can be regarded as a promising substrate for industrial production purposes.

Screening for efficient nitrogen sources for overproduction of the biomass of the functionally probiotic L. plantarum strain RPR42 in a cane molasses-based medium

Nitrogen source has a vital role for the efficient growth of lactobacilli. The effects of cheese whey, corn steep liquor, and wheat germ extract on the growth of L. plantarum strain RPR42 in cane molasses-based media was evaluated using various approaches of design of experiments. Our results showed that such protein-rich agricultural by-products significantly increase the biomass production of the strain RPR42 in cane molasses-based media. The most affecting nitrogenous material was cheese whey followed by CSL and the minor effect was reported for wheat germ extract as revealed in factorial and Box–Behnken design experiments. The replacement of costly beef extract and yeast extract with a defined mixtures of the above nitrogenous agricultural by-products in cane molasses-based medium led to production of up to 12.64 g/L/24 h of dry biomass of strain RPR42. A detectable cell density of strain RPR42 (~ 9.81 × 10⁹ CFU/mL 24 h) which was observed in such an economic medium showed that the large-scale production of the strain RPR42 tend to be feasible at significantly low costs.

Cultivation media for lactic acid bacteria used in dairy products

This review aims to familiarize the reader with research efforts on the cultivation media of lactic acid bacteria (LAB). We have also included a brief discussion on standard ingredients used in LAB media and chemically defined media as related to bacterial growth requirements. Recent research has focused on modifying standard media for the enumeration, differentiation, isolation, and identification of starter cultures and probiotics. Even though large numbers of these media have been developed to serve dairy microbial control, they have failed to provide consistent results. The research consequently points to the need to develop a reliable lactobacilli growth medium for the dairy industry.

Marine Waste Utilization as a Source of Functional and Health Compounds

Consumer demand for convenience has led to large quantities of seafood being value-added processed before marketing, resulting in large amounts of marine by-products being generated by processing industries. Several bioconversion processes have been proposed to transform some of these by-products. In addition to their relatively low value conventional use as animal feed and fertilizers, several investigations have been reported that have demonstrated the potential to add value to viscera, heads, skins, fins, trimmings, and crab and shrimp shells by extraction of lipids, bioactive peptides, enzymes, and other functional proteins and chitin that can be used in food and pharmaceutical applications. This chapter is focused on reviewing the opportunities for utilization of these marine by-products. The chapter discusses the various products and bioactive compounds that can be obtained from seafood waste and describes various methods that can be used to produce these products with the aim of highlighting opportunities to add value to these marine waste streams.

Fish viscera protein hydrolysates: Production, potential applications and functional and bioactive properties

The aquaculture and fishery chain is an important part of the economy of many countries around the world; in recent years it has experienced significant growth that generates more and more quantities of waste, which are mostly discarded, impacting the environment, despite having a useful chemical composition in various industrial sectors. This article presents a review of the agroindustrial potential of fish wastes, especially viscera, as a source for obtaining native protein and hydrolysates, explaining their production process, chemical composition and functional and bioactive properties that are important to the agricultural, cosmetic, pharmaceutical, food and nutraceutical industry.

Metagenomic approach reveals microbial diversity and predictive microbial metabolic pathways in Yucha, a traditional Li fermented food

Yucha is a typical traditional fermented food of the Li population in the Hainan province of China, and it is made up of cooked rice and fresh fish. In the present study, metagenomic approach and culture-dependent technology were applied to describe the diversity of microbiota and identify beneficial microbes in the Yucha. At the genus level, Lactobacillus was the most abundant genus (43.82% of the total reads), followed by Lactococcus, Enterococcus, Vibrio, Weissella, Pediococcus, Enterobacter, Salinivibrio, Acinetobacter, Macrococcus, Kluyvera and Clostridium; this result was confirmed by q-PCR. PCoA based on Weighted UniFrac distances showed an apparent clustering pattern for Yucha samples from different locations, and Lactobacillus sakei, Lactobacillus saniviri and Staphylococcus sciuri represented OTUs according to the major identified markers. At the microbial functional level, it was observed that there was an enrichment of metabolic functional features, including amino acid and carbohydrate metabolism, which implied that the microbial metabolism in the Yucha samples tended to be vigorous. Accordingly, we further investigated the correlation between the predominant microbes and metabolic functional features. Thirteen species of Lactobacillus (147 strains) were isolated, and Lactobacillus plantarum (60 isolates) and Lactobacillus pentosus (34 isolates) were isolated from every sample.

Probiotics production and alternative encapsulation methodologies to improve their viabilities under adverse environmental conditions

Probiotic products are dietary supplements containing live microorganisms producing beneficial health effects on the host by improving intestinal balance and nutrient absorption. Among probiotic microorganisms, those classified as lactic acid bacteria are of major importance to the food and feed industries. Probiotic cells can be produced using alternative carbon and nitrogen sources, such as agroindustrial residues, at the same time contributing to reduce process costs. On the other hand, the survival of probiotic cells in formulated food products, as well as in the host gut, is an essential nutritional aspect concerning health benefits. Therefore, several cell microencapsulation techniques have been investigated as a way to improve cell viability and survival under adverse environmental conditions, such as the gastrointestinal milieu of hosts. In this review, different aspects of probiotic cells and technologies of their related products are discussed, including formulation of culture media, and aspects of cell microencapsulation techniques required to improve their survival in the host.

Lactobacillus plantarum BL011 cultivation in industrial isolated soybean protein acid residue

In this study, physiological aspects of Lactobacillus plantarum BL011 growing in a new, all-animal free medium in bioreactors were evaluated aiming at the production of this important lactic acid bacterium. Cultivations were performed in submerged batch bioreactors using the Plackett–Burman methodology to evaluate the influence of temperature, aeration rate and stirring speed as well as the concentrations of liquid acid protein residue of soybean, soy peptone, corn steep liquor, and raw yeast extract. The results showed that all variables, except for corn steep liquor, significantly influenced biomass production. The best condition was applied to bioreactor cultures, which produced a maximal biomass of 17.87 g L⁻¹, whereas lactic acid, the most important lactic acid bacteria metabolite, peaked at 37.59 g L⁻¹, corresponding to a productivity of 1.46 g L⁻¹ h⁻¹. This is the first report on the use of liquid acid protein residue of soybean medium for L. plantarum growth. These results support the industrial use of this system as an alternative to produce probiotics without animal-derived ingredients to obtain high biomass concentrations in batch bioreactors.

Fish peptone development using enzymatic hydrolysis of silver carp by-products as a nitrogen source in Staphylococcus aureus media

Fish peptone was produced using enzymatic hydrolysis of silver carp filleting by-products by alcalase and trypsin. Also, the efficiency of the hydrolysates as a nitrogen source in Staphylococcus aureus medium was compared with commercial TSB. The results indicated that the protein hydrolysate from alcalase and trypsin had high protein content (92.92%, 91.53 respectively), and degree of hydrolysis (4.94%, 4.6% respectively).The results showed that silver carp filleting waste can be an efficient source for fish peptone production as a nitrogen source for S. aureus medium. However, the type of the used proteolytic enzyme considerably affected the performance of the resulting peptone despite the same DH. Fish peptone produced by alcalese performed significantly (P < 0.05) better than commercial TSB as a media for the bacteria while the performance of the trypsin peptone was not as good as the commercial medium.

Kinetic modeling, production and characterization of an acidic lipase produced by Enterococcus durans NCIM5427 from fish waste

Enterococcus durans NCIM5427 (ED-27), capable of producing an intracellular acid stable lipase, was isolated from fish processing waste. Its growth and subsequent lipase production was optimized by Box Behneken design (optimized conditions: 5 % v/v fish waste oil (FWO), 0.10 mg/ml fish waste protein hydrolysates (FWPH) at 48 h of fermentation time). Under optimized conditions, ED-27 showed a 3.0 fold increase (207.6 U/ml to 612.53 U/ml) in lipase production, as compared to un-optimized conditions. Cell growth and lipase production was modeled using Logistic and Luedeking-Piret model, respectively; and lipase production by ED-27 was found to be growth-associated. Lipase produced by ED-27 showed stability at low pH ranges from 2 to 5 with its optimal activity at 30 °C , pH 4.6; showed metal ion dependent activity wherein its catalytic activity was activated by barium, sodium, lithium and potassium (10 mM); reduced by calcium and magnesium (10 mM). However, iron and mercury (5 mM) completely inactivated the enzyme. In addition, modifying agents like SDS, DTT, β-ME (1%v/v) increased activity of lipase of ED-27; while, PMSF, DEPC and ascorbic acid resulted in a marked decrease. ED-27 had maximum cell growth of 9.90309 log CFU/ml under optimized conditions as compared to 13 log CFU/ml in MRS. The lipase produced has potential application in poultry and slaughterhouse waste management.

Identification, technological and safety characterization of Lactobacillus sakei and Lactobacillus curvatus isolated from Argentinean anchovies (Engraulis anchoita)

In this study, the identification and characterization of Lactobacillus previously isolated from fresh anchovies (Engraulis anchoita) are investigated. 16S rDNA partial sequencing assigned all the isolates to belong to the Lactobacillus sakei/curvatus group. Fourteen out of 15 isolates were identified as L. sakei by phenotypic traits: they exhibited catalase activity and fermented melibiose, although only 10 of them hydrolyzed arginine. These results were confirmed by multiplex PCR-based restriction enzyme analysis with HindIII and by restriction fragment length polymorphic (RFLP) analysis of the 16S-23S rDNA intergenic spacer region with TaqI. Among identified isolates, four L. sakei strains and the sole L. curvatus strain showing sensitivity to chloramphenicol, erythromycin and tetracycline and exhibiting high tolerance to NaCl (10-18%) were unable to produce neither dextran nor biogenic amines. Based on technological and safety features, L. sakei SACB₇04 and L. curvatus SACB03a naturally present in fresh anchovies may be promising strains for the development of a starter culture to accelerate and control the fermentation of salt fermented anchovy-based products.

Comparison of Lipase Production by Enterococcus faecium MTCC 5695 and Pediococcus acidilactici MTCC 11361 Using Fish Waste as Substrate: Optimization of Culture Conditions by Response Surface Methodology

A medium using fish waste as substrate was designed for production of lipase by Enterococcus faecium MTCC 5695 and Pediococcus acidilactici MTCC 11361. Medium components and culture conditions (fish waste protein hydrolysate (FWPH) concentration, fish waste oil (FWO) concentration, pH, temperature, and fermentation time) which affect lipase production were screened using factorial (5 factors ∗ 2 levels) design of which FWPH concentration, FWO concentration, and fermentation time showed significance (P < 0.05). The levels of these factors were optimized further by Box-Behnken design using response surface methodology (RSM). Optimized conditions were found to be 5% v/v FWO, 0.15 mg/mL FWPH and 24 h of fermentation time for MTCC 5695, and 4% v/v FWO, 0.15 mg/mL FWPH and 24 h of fermentation for MTCC 11361, which were further validated. Under optimized conditions, MTCC 5695 and MTCC 11361 showed 3.15- (543.63 to 1715 U/mL) and 2.3- (214.74 to 493 U/mL) fold increase in lipase production, respectively, as compared to unoptimized conditions.

Pelagic fish hydrolysates as peptones for bacterial culture media

For several years in the Quebec fisheries’ industry,landings of pelagic fish have been calculated at over 4000 tons. These under-exploited species, rich in lipids and proteins, could be used in valuable new products. In the present study, hydrolysates of mackerel and herring were produced and utilized as sources of peptones in the formulation of new bacterial culture media. The molecular weight distribution analysis showed that molecules present in the hydrolysates were lower than 1300 Da for herring, and lower than 930 Da for mackerel. The formulated media were compared with reference media using 6 bacterial strains (3 lactic acid (LAB) and 3 non-lactic). The absorbance (OD) and carbohydrate measurements revealed that the formulated media possessed similar yields in comparison with the reference media. Finally, the inhibition of Listeria innocua by LAB bacteriocins was evaluated. Results obtained for Pediococcus acidilactici demonstrated high activities for each medium studied. Thus, the medium containing herring peptones generated the highest bacteriocin titre (32768 AU/mL), followed by both the medium containing mackerel peptones and the MRS7 medium (16384 AU/mL). Each medium containing the fish hydrolysates efficiently supported the growth of the bacterial strains. Pelagic fish peptones are promising as a novel bacterial culture media.

The chitinolytic system of Lactococcus lactis ssp. lactis comprises a nonprocessive chitinase and a chitin-binding protein that promotes the degradation of alpha- and beta-chitin

It has recently been shown that the Gram-negative bacterium Serratia marcescens produces an accessory nonhydrolytic chitin-binding protein that acts in synergy with chitinases. This provided the first example of the production of dedicated helper proteins for the turnover of recalcitrant polysaccharides. Chitin-binding proteins belong to family 33 of the carbohydrate-binding modules, and genes putatively encoding these proteins occur in many microorganisms. To obtain an impression of the functional conservation of these proteins, we studied the chitinolytic system of the Gram-positive Lactococcus lactis ssp. lactis IL1403. The genome of this lactic acid bacterium harbours a simple chitinolytic machinery, consisting of one family 18 chitinase (named LlChi18A), one family 33 chitin-binding protein (named LlCBP33A) and one family 20 N-acetylhexosaminidase. We cloned, overexpressed and characterized LlChi18A and LlCBP33A. Sequence alignments and structural modelling indicated that LlChi18A has a shallow substrate-binding groove characteristic of nonprocessive endochitinases. Enzymology showed that LlChi18A was able to hydrolyse both chitin oligomers and artificial substrates, with no sign of processivity. Although the chitin-binding protein from S. marcescens only bound to beta-chitin, LlCBP33A was found to bind to both alpha- and beta-chitin. LlCBP33A increased the hydrolytic efficiency of LlChi18A to both alpha- and beta-chitin. These results show the general importance of chitin-binding proteins in chitin turnover, and provide the first example of a family 33 chitin-binding protein that increases chitinase efficiency towards alpha-chitin.

Effects of cultivation conditions on the diversity of microbes involved in the conversion of rice straw to fodder

To confirm the optimum cultivation conditions for analyzing lactic acid bacterial communities and to provide the cultivation foundation for lactic acid bacterial communities that were used to convert straw into fodder, fermented rice straw was inoculated into 13 different broths. After 48 h of cultivation, pH values, volatile products, and microbial diversity were analyzed. Except for LAB broth, the pH values of the other broths could decrease to approximately 4.5. GC/MS analysis showed that lactic acid in Tomato MRS broth, MRS broth, LAB broth, and Tomato juice broth was higher than that in the other broths. DNA concentration analysis showed that the counts of microbes in Tomato MRS broth were 2.5 times of those in other broths and that tomato juice favored the reproduction of the microbes. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the number of lactic acid bacterial species in HYA broth, Tomato juice broth, and Tomato MRS broth were higher than those in the other broths.